diff --git a/F3:F303/InterfaceBoard/Makefile b/F3:F303/InterfaceBoard/Makefile
new file mode 100644
index 0000000..aa55d66
--- /dev/null
+++ b/F3:F303/InterfaceBoard/Makefile
@@ -0,0 +1,9 @@
+BINARY		:= multiiface
+# MCU code
+MCU			:= F303xc
+# change this linking script depending on particular MCU model,
+LDSCRIPT	:= stm32f303xC.ld
+DEFINES := -DUSB1_16
+
+include ../makefile.f3
+include ../../makefile.stm32
diff --git a/F3:F303/InterfaceBoard/flash.c b/F3:F303/InterfaceBoard/flash.c
new file mode 100644
index 0000000..3088d3b
--- /dev/null
+++ b/F3:F303/InterfaceBoard/flash.c
@@ -0,0 +1,193 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stm32f3.h>
+
+#include "flash.h"
+#include "strfunc.h"
+#include "usb_dev.h"    // printout
+#include "usb_descr.h"  // descriptors
+#include <string.h> // memcpy
+
+extern const uint32_t __varsstart, _BLOCKSIZE;
+static const uint32_t FLASH_blocksize = (uint32_t)&_BLOCKSIZE;
+static uint32_t maxCnum = 2048 / sizeof(user_conf); // can't use blocksize here
+
+static int write2flash(const void*, const void*, uint32_t);
+const user_conf *Flash_Data = (const user_conf *)(&__varsstart);
+user_conf the_conf = {
+    .userconf_sz = sizeof(user_conf),
+    .iInterface = {
+        [ISerial0] = u"usbserial0",
+        [ISerial1] = u"usbserial1",
+        [ISerial2] = u"usbserial2",
+        [ISerial3] = u"usbserial3",
+        [ISerial4] = u"usbserial4",
+        [ISPI]     = u"usbSPI",
+        [ICAN]     = u"usbCAN"
+    },
+    .iIlengths = {20,20,20,20,20,12,12},
+};
+
+int currentconfidx = -1; // index of current configuration
+
+/**
+ * @brief binarySearch - binary search in flash for last non-empty cell
+ *          any struct searched should have its sizeof() @ the first field!!!
+ * @param l - left index
+ * @param r - right index (should be @1 less than last index!)
+ * @param start - starting address
+ * @param stor_size - size of structure to search
+ * @return index of non-empty cell or -1
+ */
+static int binarySearch(int r, const uint8_t *start, int stor_size){
+    int l = 0;
+    while(r >= l){
+        int mid = l + (r - l) / 2;
+        const uint8_t *s = start + mid * stor_size;
+        if(*((const uint16_t*)s) == stor_size){
+            if(*((const uint16_t*)(s + stor_size)) == 0xffff){ // next is free
+                return mid;
+            }else{ // element is to the right
+                l = mid + 1;
+            }
+        }else{ // element is to the left
+            r = mid - 1;
+        }
+    }
+    return -1; // not found
+}
+
+/**
+ * @brief flashstorage_init - initialization of user conf storage
+ * run in once @ start
+ */
+void flashstorage_init(){
+    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
+        uint32_t flsz = FLASH_SIZE * 1024; // size in bytes
+        flsz -= (uint32_t)(&__varsstart) - FLASH_BASE;
+        maxCnum = flsz / sizeof(user_conf);
+    }
+    // -1 if there's no data at all & flash is clear; maxnum-1 if flash is full
+    currentconfidx = binarySearch((int)maxCnum-2, (const uint8_t*)Flash_Data, sizeof(user_conf));
+    if(currentconfidx > -1){
+        memcpy(&the_conf, &Flash_Data[currentconfidx], sizeof(user_conf));
+    }
+}
+
+// store new configuration
+// @return 0 if all OK
+int store_userconf(){
+    // maxnum - 3 means that there always should be at least one empty record after last data
+    // for binarySearch() checking that there's nothing more after it!
+    if(currentconfidx > (int)maxCnum - 3){ // there's no more place
+        currentconfidx = 0;
+        if(erase_storage(-1)) return 1;
+    }else ++currentconfidx; // take next data position (0 - within first run after firmware flashing)
+    return write2flash((const void*)&Flash_Data[currentconfidx], &the_conf, sizeof(the_conf));
+}
+
+static int write2flash(const void *start, const void *wrdata, uint32_t stor_size){
+    int ret = 0;
+    if (FLASH->CR & FLASH_CR_LOCK){ // unloch flash
+        FLASH->KEYR = FLASH_KEY1;
+        FLASH->KEYR = FLASH_KEY2;
+    }
+    while (FLASH->SR & FLASH_SR_BSY)  IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPERR; // clear all flags
+    FLASH->CR |= FLASH_CR_PG;
+    const uint16_t *data = (const uint16_t*) wrdata;
+    volatile uint16_t *address = (volatile uint16_t*) start;
+    uint32_t i, count = (stor_size + 1) / 2;
+    for(i = 0; i < count; ++i){
+        *(volatile uint16_t*)(address + i) = data[i];
+        while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+        if(*(volatile uint16_t*)(address + i) != data[i]){
+            USB_sendstr("DON'T MATCH!\n");
+            ret = 1;
+            break;
+        }
+        if(FLASH->SR & FLASH_SR_PGERR){
+            USB_sendstr("Prog err\n");
+            ret = 1; // program error - meet not 0xffff
+            break;
+        }
+        FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPERR;
+    }
+    FLASH->CR &= ~(FLASH_CR_PG);
+    return ret;
+}
+
+// erase Nth page of flash storage (flash should be prepared!)
+static int erase_pageN(int N){
+    int ret = 0;
+#ifdef EBUG
+    //CMDWR("Erase page #"); CMDWR(u2str(N)); CMDn();
+#endif
+    FLASH->AR = (uint32_t)Flash_Data + N*FLASH_blocksize;
+    FLASH->CR |= FLASH_CR_STRT;
+    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP;
+    if(FLASH->SR & FLASH_SR_WRPERR){ /* Check Write protection error */
+        ret = 1;
+        FLASH->SR = FLASH_SR_WRPERR; /* Clear the flag by software by writing it at 1*/
+    }
+    return ret;
+}
+
+// erase full storage (npage < 0) or its nth page; @return 0 if all OK
+int erase_storage(int npage){
+    int ret = 0;
+    uint32_t end = 1, start = 0, flsz = 0;
+    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
+        flsz = FLASH_SIZE * 1024; // size in bytes
+        flsz -= (uint32_t)Flash_Data - FLASH_BASE;
+    }
+    end = flsz / FLASH_blocksize;
+/*
+#ifdef EBUG
+    CMDWR("FLASH_SIZE="); CMDWR(u2str(FLASH_SIZE));
+    CMDWR("\nflsz="); CMDWR(u2str(flsz));
+    CMDWR("\nend="); CMDWR(u2str(end));
+    CMDWR("\ncurrentconfidx="); CMDWR(u2str(currentconfidx));
+    CMDWR("\nmaxCnum="); CMDWR(u2str(maxCnum));
+    CMDn();
+#endif
+*/
+    if(end == 0 || end >= FLASH_SIZE) return 1;
+    if(npage > -1){ // erase only one page
+        if((uint32_t)npage >= end) return 1;
+        start = npage;
+        end = start + 1;
+    }
+    if((FLASH->CR & FLASH_CR_LOCK) != 0){
+        FLASH->KEYR = FLASH_KEY1;
+        FLASH->KEYR = FLASH_KEY2;
+    }
+    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPERR;
+    FLASH->CR |= FLASH_CR_PER;
+    for(uint32_t i = start; i < end; ++i){
+        if(erase_pageN(i)){
+            ret = 1;
+            break;
+        }
+    }
+    FLASH->CR &= ~FLASH_CR_PER;
+    return ret;
+}
+
diff --git a/F3:F303/InterfaceBoard/flash.h b/F3:F303/InterfaceBoard/flash.h
new file mode 100644
index 0000000..4f3f564
--- /dev/null
+++ b/F3:F303/InterfaceBoard/flash.h
@@ -0,0 +1,46 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <stdint.h>
+#include "usb_descr.h"
+
+// register with flash size (in blocks)
+#ifndef FLASH_SIZE_REG
+#define FLASH_SIZE_REG      ((uint32_t)0x1FFFF7CC)
+#endif
+#define FLASH_SIZE          *((uint16_t*)FLASH_SIZE_REG)
+
+// maximal size (in letters) of iInterface for settings
+#define MAX_IINTERFACE_SZ   (16)
+
+/*
+ * struct to save user configurations
+ */
+typedef struct __attribute__((packed, aligned(4))){
+    uint16_t userconf_sz;       // "magick number"
+    uint16_t iInterface[InterfacesAmount][MAX_IINTERFACE_SZ]; // hryunikod!
+    uint8_t iIlengths[InterfacesAmount];
+} user_conf;
+
+extern user_conf the_conf;
+extern int currentconfidx;
+
+void flashstorage_init();
+int store_userconf();
+int erase_storage(int npage);
diff --git a/F3:F303/InterfaceBoard/hardware.c b/F3:F303/InterfaceBoard/hardware.c
new file mode 100644
index 0000000..d3c8237
--- /dev/null
+++ b/F3:F303/InterfaceBoard/hardware.c
@@ -0,0 +1,14 @@
+#include "hardware.h"
+
+static inline void gpio_setup(){
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN; // for USART and LEDs
+    for(int i = 0; i < 10000; ++i) nop();
+    // USB - alternate function 14 @ pins PA11/PA12; SWD - AF0 @PA13/14
+    GPIOA->AFR[1] = AFRf(14, 11) | AFRf(14, 12);
+    GPIOA->MODER = MODER_O(10) | MODER_AF(11) | MODER_AF(12) | MODER_AF(13) | MODER_AF(14);
+}
+
+void hw_setup(){
+    gpio_setup();
+}
+
diff --git a/F3:F303/InterfaceBoard/hardware.h b/F3:F303/InterfaceBoard/hardware.h
new file mode 100644
index 0000000..457c6fc
--- /dev/null
+++ b/F3:F303/InterfaceBoard/hardware.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <stm32f3.h>
+
+#define USBPU_port  GPIOA
+#define USBPU_pin   (1<<10)
+#define USBPU_ON()  pin_clear(USBPU_port, USBPU_pin)
+#define USBPU_OFF() pin_set(USBPU_port, USBPU_pin)
+
+extern volatile uint32_t Tms;
+
+void hw_setup();
+
diff --git a/F3:F303/InterfaceBoard/main.c b/F3:F303/InterfaceBoard/main.c
new file mode 100644
index 0000000..af65cd3
--- /dev/null
+++ b/F3:F303/InterfaceBoard/main.c
@@ -0,0 +1,57 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "flash.h"
+#include "hardware.h"
+#include "proto.h"
+#include "usb_dev.h"
+
+#define MAXSTRLEN    RBINSZ
+
+volatile uint32_t Tms = 0;
+
+void sys_tick_handler(void){
+    ++Tms;
+}
+
+int main(void){
+    char inbuff[MAXSTRLEN+1];
+    if(StartHSE()){
+        SysTick_Config((uint32_t)72000); // 1ms
+    }else{
+        StartHSI();
+        SysTick_Config((uint32_t)48000); // 1ms
+    }
+    flashstorage_init();
+    hw_setup();
+    USBPU_OFF();
+    USB_setup();
+    //uint32_t ctr = Tms;
+    USBPU_ON();
+    while(1){
+        /*if(Tms - ctr > 499){
+            ctr = Tms;
+        }*/
+        if(!usbON) continue;
+        int l = USB_receivestr(inbuff, MAXSTRLEN);
+        if(l < 0) USB_sendstr("ERROR: USB buffer overflow or string was too long\n");
+        else if(l){
+            const char *ans = parse_cmd(inbuff);
+            if(ans) USB_sendstr(ans);
+        }
+    }
+}
diff --git a/F3:F303/InterfaceBoard/multiiface.bin b/F3:F303/InterfaceBoard/multiiface.bin
new file mode 100755
index 0000000..aac465a
Binary files /dev/null and b/F3:F303/InterfaceBoard/multiiface.bin differ
diff --git a/F3:F303/InterfaceBoard/multiiface.cflags b/F3:F303/InterfaceBoard/multiiface.cflags
new file mode 100644
index 0000000..68d5165
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.cflags
@@ -0,0 +1 @@
+-std=c17
\ No newline at end of file
diff --git a/F3:F303/InterfaceBoard/multiiface.config b/F3:F303/InterfaceBoard/multiiface.config
new file mode 100644
index 0000000..1cf1964
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.config
@@ -0,0 +1,7 @@
+// Add predefined macros for your project here. For example:
+// #define THE_ANSWER 42
+#define EBUG
+#define STM32F3
+#define STM32F303xb
+#define __thumb2__ 1
+#define __ARM_ARCH_7M__
diff --git a/F3:F303/InterfaceBoard/multiiface.creator b/F3:F303/InterfaceBoard/multiiface.creator
new file mode 100644
index 0000000..e94cbbd
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.creator
@@ -0,0 +1 @@
+[General]
diff --git a/F3:F303/InterfaceBoard/multiiface.creator.user b/F3:F303/InterfaceBoard/multiiface.creator.user
new file mode 100644
index 0000000..bd2b309
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.creator.user
@@ -0,0 +1,214 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE QtCreatorProject>
+<!-- Written by QtCreator 18.0.1, 2025-12-28T20:25:46. -->
+<qtcreator>
+ <data>
+  <variable>EnvironmentId</variable>
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+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.DefaultDisplayName">Clean</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName">Clean</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.BuildSteps.Clean</value>
+    </valuemap>
+    <value type="int" key="ProjectExplorer.BuildConfiguration.BuildStepListCount">2</value>
+    <value type="bool" key="ProjectExplorer.BuildConfiguration.ClearSystemEnvironment">false</value>
+    <valuelist type="QVariantList" key="ProjectExplorer.BuildConfiguration.CustomParsers"/>
+    <value type="bool" key="ProjectExplorer.BuildConfiguration.ParseStandardOutput">false</value>
+    <valuelist type="QVariantList" key="ProjectExplorer.BuildConfiguration.UserEnvironmentChanges"/>
+    <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName">Default</value>
+    <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">GenericProjectManager.GenericBuildConfiguration</value>
+    <value type="qlonglong" key="ProjectExplorer.Target.ActiveDeployConfiguration">0</value>
+    <value type="qlonglong" key="ProjectExplorer.Target.ActiveRunConfiguration">0</value>
+    <valuemap type="QVariantMap" key="ProjectExplorer.Target.DeployConfiguration.0">
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+      <value type="QString" key="ProjectExplorer.ProjectConfiguration.DefaultDisplayName">Deploy</value>
+      <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName">Deploy</value>
+      <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.BuildSteps.Deploy</value>
+     </valuemap>
+     <value type="int" key="ProjectExplorer.BuildConfiguration.BuildStepListCount">1</value>
+     <valuemap type="QVariantMap" key="ProjectExplorer.DeployConfiguration.CustomData"/>
+     <value type="bool" key="ProjectExplorer.DeployConfiguration.CustomDataEnabled">false</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.DefaultDeployConfiguration</value>
+    </valuemap>
+    <value type="qlonglong" key="ProjectExplorer.Target.DeployConfigurationCount">1</value>
+    <valuemap type="QVariantMap" key="ProjectExplorer.Target.RunConfiguration.0">
+     <value type="bool" key="Analyzer.Perf.Settings.UseGlobalSettings">true</value>
+     <value type="bool" key="Analyzer.QmlProfiler.Settings.UseGlobalSettings">true</value>
+     <value type="bool" key="Analyzer.Valgrind.Settings.UseGlobalSettings">true</value>
+     <valuelist type="QVariantList" key="CustomOutputParsers"/>
+     <value type="int" key="PE.EnvironmentAspect.Base">2</value>
+     <valuelist type="QVariantList" key="PE.EnvironmentAspect.Changes"/>
+     <value type="bool" key="PE.EnvironmentAspect.PrintOnRun">false</value>
+     <value type="QString" key="PerfRecordArgsId">-e cpu-cycles --call-graph dwarf,4096 -F 250</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName"></value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.CustomExecutableRunConfiguration</value>
+     <value type="QString" key="ProjectExplorer.RunConfiguration.BuildKey"></value>
+     <value type="bool" key="ProjectExplorer.RunConfiguration.Customized">false</value>
+     <value type="QString" key="ProjectExplorer.RunConfiguration.UniqueId"></value>
+     <value type="bool" key="RunConfiguration.UseCppDebuggerAuto">true</value>
+     <value type="bool" key="RunConfiguration.UseQmlDebuggerAuto">true</value>
+    </valuemap>
+    <value type="qlonglong" key="ProjectExplorer.Target.RunConfigurationCount">1</value>
+   </valuemap>
+   <value type="qlonglong" key="ProjectExplorer.Target.BuildConfigurationCount">1</value>
+   <valuemap type="QVariantMap" key="ProjectExplorer.Target.DeployConfiguration.0">
+    <valuemap type="QVariantMap" key="ProjectExplorer.BuildConfiguration.BuildStepList.0">
+     <value type="qlonglong" key="ProjectExplorer.BuildStepList.StepsCount">0</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.DefaultDisplayName">Deploy</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName">Deploy</value>
+     <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.BuildSteps.Deploy</value>
+    </valuemap>
+    <value type="int" key="ProjectExplorer.BuildConfiguration.BuildStepListCount">1</value>
+    <valuemap type="QVariantMap" key="ProjectExplorer.DeployConfiguration.CustomData"/>
+    <value type="bool" key="ProjectExplorer.DeployConfiguration.CustomDataEnabled">false</value>
+    <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.DefaultDeployConfiguration</value>
+   </valuemap>
+   <value type="qlonglong" key="ProjectExplorer.Target.DeployConfigurationCount">1</value>
+   <valuemap type="QVariantMap" key="ProjectExplorer.Target.RunConfiguration.0">
+    <value type="bool" key="Analyzer.Perf.Settings.UseGlobalSettings">true</value>
+    <value type="bool" key="Analyzer.QmlProfiler.Settings.UseGlobalSettings">true</value>
+    <value type="bool" key="Analyzer.Valgrind.Settings.UseGlobalSettings">true</value>
+    <valuelist type="QVariantList" key="CustomOutputParsers"/>
+    <value type="int" key="PE.EnvironmentAspect.Base">2</value>
+    <valuelist type="QVariantList" key="PE.EnvironmentAspect.Changes"/>
+    <value type="bool" key="PE.EnvironmentAspect.PrintOnRun">false</value>
+    <value type="QString" key="PerfRecordArgsId">-e cpu-cycles --call-graph dwarf,4096 -F 250</value>
+    <value type="QString" key="ProjectExplorer.ProjectConfiguration.DisplayName"></value>
+    <value type="QString" key="ProjectExplorer.ProjectConfiguration.Id">ProjectExplorer.CustomExecutableRunConfiguration</value>
+    <value type="QString" key="ProjectExplorer.RunConfiguration.BuildKey"></value>
+    <value type="bool" key="ProjectExplorer.RunConfiguration.Customized">false</value>
+    <value type="QString" key="ProjectExplorer.RunConfiguration.UniqueId"></value>
+    <value type="bool" key="RunConfiguration.UseCppDebuggerAuto">true</value>
+    <value type="bool" key="RunConfiguration.UseQmlDebuggerAuto">true</value>
+   </valuemap>
+   <value type="qlonglong" key="ProjectExplorer.Target.RunConfigurationCount">1</value>
+  </valuemap>
+ </data>
+ <data>
+  <variable>ProjectExplorer.Project.TargetCount</variable>
+  <value type="qlonglong">1</value>
+ </data>
+ <data>
+  <variable>Version</variable>
+  <value type="int">22</value>
+ </data>
+</qtcreator>
diff --git a/F3:F303/InterfaceBoard/multiiface.cxxflags b/F3:F303/InterfaceBoard/multiiface.cxxflags
new file mode 100644
index 0000000..6435dfc
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.cxxflags
@@ -0,0 +1 @@
+-std=c++17
\ No newline at end of file
diff --git a/F3:F303/InterfaceBoard/multiiface.files b/F3:F303/InterfaceBoard/multiiface.files
new file mode 100644
index 0000000..6203f9c
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.files
@@ -0,0 +1,20 @@
+flash.c
+flash.h
+hardware.c
+hardware.h
+main.c
+proto.c
+proto.h
+ringbuffer.c
+ringbuffer.h
+strfunc.c
+strfunc.h
+usb.c
+usb.h
+usb_descr.c
+usb_descr.h
+usb_dev.c
+usb_dev.h
+usb_lib.c
+usb_lib.h
+usbhw.h
diff --git a/F3:F303/InterfaceBoard/multiiface.includes b/F3:F303/InterfaceBoard/multiiface.includes
new file mode 100644
index 0000000..06d1130
--- /dev/null
+++ b/F3:F303/InterfaceBoard/multiiface.includes
@@ -0,0 +1,6 @@
+.
+../inc
+../inc/Fx
+../inc/cm
+../inc/ld
+../inc/startup
diff --git a/F3:F303/InterfaceBoard/openocd.cfg b/F3:F303/InterfaceBoard/openocd.cfg
new file mode 100644
index 0000000..7ee51bf
--- /dev/null
+++ b/F3:F303/InterfaceBoard/openocd.cfg
@@ -0,0 +1,4 @@
+set FLASH_SIZE 0x40000
+
+source [find interface/stlink-v2-1.cfg]
+source [find target/stm32f3x.cfg]
diff --git a/F3:F303/InterfaceBoard/proto.c b/F3:F303/InterfaceBoard/proto.c
new file mode 100644
index 0000000..e2c6438
--- /dev/null
+++ b/F3:F303/InterfaceBoard/proto.c
@@ -0,0 +1,118 @@
+#include <stm32f3.h>
+#include <string.h>
+
+#include "flash.h"
+#include "strfunc.h"
+#include "usb_dev.h"
+#include "version.inc"
+
+static const char *const sOKn = "OK\n", *const sERRn = "ERR\n";
+
+//#define LOCBUFFSZ       (32)
+// local buffer for I2C data to send
+//static uint8_t locBuffer[LOCBUFFSZ];
+extern volatile uint32_t Tms;
+
+const char *helpstring =
+        "https://github.com/eddyem/stm32samples/tree/master/F3:F303/InterfaceBoard build#" BUILD_NUMBER " @ " BUILD_DATE "\n"
+        "d - dump flash\n"
+        "ix - rename interface number x (0..6)\n"
+        "Ex - erase full storage (witout x) or only page x\n"
+        "F - reinit configurations from flash\n"
+        "R - soft reset\n"
+        "S - store new parameters into flash\n"
+        "T - print current Tms\n"
+;
+
+static void dumpflash(){
+    USB_sendstr("userconf_sz="); USB_sendstr(u2str(the_conf.userconf_sz));
+    USB_sendstr("\ncurrentconfidx="); USB_sendstr(i2str(currentconfidx));
+    USB_putbyte('\n');
+    for(int i = 0; i < InterfacesAmount; ++i){
+        USB_sendstr("interface"); USB_putbyte('0' + i);
+        USB_putbyte('=');
+        int l = the_conf.iIlengths[i] / 2;
+        char *ptr = (char*) the_conf.iInterface[i];
+        for(int j = 0; j < l; ++j){
+            USB_putbyte(*ptr);
+            ptr += 2;
+        }
+        USB_putbyte('\n');
+    }
+}
+
+static void setiface(const char *str){
+    if(!str || !*str) goto err;
+    uint32_t N;
+    const char *nxt = getnum(str, &N);
+    if(!nxt || nxt == str || N >= InterfacesAmount) goto err;
+    nxt = strchr(nxt, '=');
+    if(!nxt || !*(++nxt)) goto err;
+    nxt = omit_spaces(nxt);
+    if(!nxt || !*nxt) goto err;
+    int l = strlen(nxt);
+    if(l > MAX_IINTERFACE_SZ) goto err;
+    the_conf.iIlengths[N] = (uint8_t) l * 2;
+    char *ptr = (char*)the_conf.iInterface[N];
+    for(int i = 0; i < l; ++i){
+        *ptr++ = *nxt++;
+        *ptr++ = 0;
+    }
+    USB_sendstr(sOKn);
+    return;
+err:
+    USB_sendstr(sERRn);
+}
+
+static const char* erpg(const char *str){
+    uint32_t N;
+    if(str == getnum(str, &N)) return sERRn;
+    if(erase_storage(N)) return sERRn;
+    return sOKn;
+}
+
+const char *parse_cmd(const char *buf){
+    if(!buf || !*buf) return NULL;
+    if(strlen(buf) > 1){
+        // "long" commands
+        char c = *buf++;
+        switch(c){
+            case 'E':
+                return erpg(buf);
+            case 'i':
+                setiface(buf);
+                return NULL;
+            break;
+            default:
+                return buf-1; // echo wrong data
+        }
+    }
+    // "short" commands
+    switch(*buf){
+        case 'd':
+            dumpflash();
+        break;
+        case 'E':
+            if(erase_storage(-1)) return sERRn;
+            return sOKn;
+        break;
+        case 'F':
+            flashstorage_init();
+            return sOKn;
+        case 'R':
+            NVIC_SystemReset();
+            return NULL;
+        case 'S':
+            if(store_userconf()) return sERRn;
+            return sOKn;
+        case 'T':
+            USB_sendstr("T=");
+            USB_sendstr(u2str(Tms));
+            newline();
+            break;
+        default: // help
+            USB_sendstr(helpstring);
+        break;
+    }
+    return NULL;
+}
diff --git a/F3:F303/InterfaceBoard/proto.h b/F3:F303/InterfaceBoard/proto.h
new file mode 100644
index 0000000..5c6c029
--- /dev/null
+++ b/F3:F303/InterfaceBoard/proto.h
@@ -0,0 +1,4 @@
+#pragma once
+
+char *parse_cmd(char *buf);
+
diff --git a/F3:F303/InterfaceBoard/ringbuffer.c b/F3:F303/InterfaceBoard/ringbuffer.c
new file mode 100644
index 0000000..b0ffe8e
--- /dev/null
+++ b/F3:F303/InterfaceBoard/ringbuffer.c
@@ -0,0 +1,166 @@
+/*
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ringbuffer.h"
+
+static int datalen(ringbuffer *b){
+    if(b->tail >= b->head) return (b->tail - b->head);
+    else return (b->length - b->head + b->tail);
+}
+
+// stored data length
+int RB_datalen(ringbuffer *b){
+    if(b->busy) return -1;
+    b->busy = 1;
+    int l = datalen(b);
+    b->busy = 0;
+    return l;
+}
+
+static int hasbyte(ringbuffer *b, uint8_t byte){
+    if(b->head == b->tail) return -1; // no data in buffer
+    int startidx = b->head;
+    if(b->head > b->tail){ //
+        for(int found = b->head; found < b->length; ++found)
+            if(b->data[found] == byte) return found;
+        startidx = 0;
+    }
+    for(int found = startidx; found < b->tail; ++found)
+        if(b->data[found] == byte) return found;
+    return -1;
+}
+
+/**
+ * @brief RB_hasbyte - check if buffer has given byte stored
+ * @param b - buffer
+ * @param byte - byte to find
+ * @return index if found, -1 if none or busy
+ */
+int RB_hasbyte(ringbuffer *b, uint8_t byte){
+    if(b->busy) return -1;
+    b->busy = 1;
+    int ret = hasbyte(b, byte);
+    b->busy = 0;
+    return ret;
+}
+
+// poor memcpy
+static void mcpy(uint8_t *targ, const uint8_t *src, int l){
+    while(l--) *targ++ = *src++;
+}
+
+// increment head or tail
+TRUE_INLINE void incr(ringbuffer *b, volatile int *what, int n){
+    *what += n;
+    if(*what >= b->length) *what -= b->length;
+}
+
+static int read(ringbuffer *b, uint8_t *s, int len){
+    int l = datalen(b);
+    if(!l) return 0;
+    if(l > len) l = len;
+    int _1st = b->length - b->head;
+    if(_1st > l) _1st = l;
+    if(_1st > len) _1st = len;
+    mcpy(s, b->data + b->head, _1st);
+    if(_1st < len && l > _1st){
+        mcpy(s+_1st, b->data, l - _1st);
+        incr(b, &b->head, l);
+        return l;
+    }
+    incr(b, &b->head, _1st);
+    return _1st;
+}
+
+/**
+ * @brief RB_read - read data from ringbuffer
+ * @param b - buffer
+ * @param s - array to write data
+ * @param len - max len of `s`
+ * @return bytes read or -1 if busy
+ */
+int RB_read(ringbuffer *b, uint8_t *s, int len){
+    if(b->busy) return -1;
+    b->busy = 1;
+    int r = read(b, s, len);
+    b->busy = 0;
+    return r;
+}
+
+static int readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len){
+    int idx = hasbyte(b, byte);
+    if(idx < 0) return 0;
+    int partlen = idx + 1 - b->head;
+    // now calculate length of new data portion
+    if(idx < b->head) partlen += b->length;
+    if(partlen > len) return -read(b, s, len);
+    return read(b, s, partlen);
+}
+
+/**
+ * @brief RB_readto fill array `s` with data until byte `byte` (with it)
+ * @param b - ringbuffer
+ * @param byte - check byte
+ * @param s - buffer to write data
+ * @param len - length of `s`
+ * @return amount of bytes written (negative, if len<data in buffer or buffer is busy)
+ */
+int RB_readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len){
+    if(b->busy) return -1;
+    b->busy = 1;
+    int n = readto(b, byte, s, len);
+    b->busy = 0;
+    return n;
+}
+
+static int write(ringbuffer *b, const uint8_t *str, int l){
+    int r = b->length - 1 - datalen(b); // rest length
+    if(l > r || !l) return 0;
+    int _1st = b->length - b->tail;
+    if(_1st > l) _1st = l;
+    mcpy(b->data + b->tail, str, _1st);
+    if(_1st < l){ // add another piece from start
+        mcpy(b->data, str+_1st, l-_1st);
+    }
+    incr(b, &b->tail, l);
+    return l;
+}
+
+/**
+ * @brief RB_write - write some data to ringbuffer
+ * @param b - buffer
+ * @param str - data
+ * @param l - length
+ * @return amount of bytes written or -1 if busy
+ */
+int RB_write(ringbuffer *b, const uint8_t *str, int l){
+    if(b->busy) return -1;
+    b->busy = 1;
+    int w = write(b, str, l);
+    b->busy = 0;
+    return w;
+}
+
+// just delete all information in buffer `b`
+int RB_clearbuf(ringbuffer *b){
+    if(b->busy) return -1;
+    b->busy = 1;
+    b->head = 0;
+    b->tail = 0;
+    b->busy = 0;
+    return 1;
+}
diff --git a/F3:F303/InterfaceBoard/ringbuffer.h b/F3:F303/InterfaceBoard/ringbuffer.h
new file mode 100644
index 0000000..ed2cf95
--- /dev/null
+++ b/F3:F303/InterfaceBoard/ringbuffer.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#if defined STM32F0
+#include <stm32f0.h>
+#elif defined STM32F1
+#include <stm32f1.h>
+#elif defined STM32F3
+#include <stm32f3.h>
+#endif
+
+typedef struct{
+    uint8_t *data;      // data buffer
+    const int length;   // its length
+    int head;           // head index
+    int tail;           // tail index
+    volatile int busy; // == TRUE if buffer is busy now
+} ringbuffer;
+
+int RB_read(ringbuffer *b, uint8_t *s, int len);
+int RB_readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len);
+int RB_hasbyte(ringbuffer *b, uint8_t byte);
+int RB_write(ringbuffer *b, const uint8_t *str, int l);
+int RB_datalen(ringbuffer *b);
+int RB_clearbuf(ringbuffer *b);
diff --git a/F3:F303/InterfaceBoard/strfunc.c b/F3:F303/InterfaceBoard/strfunc.c
new file mode 100644
index 0000000..004e62f
--- /dev/null
+++ b/F3:F303/InterfaceBoard/strfunc.c
@@ -0,0 +1,267 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32f3.h>
+
+/**
+ * @brief hexdump - dump hex array by 16 bytes in string
+ * @param sendfun - function to send data
+ * @param arr - array to dump
+ * @param len - length of `arr`
+ */
+void hexdump(int (*sendfun)(const char *s), uint8_t *arr, uint16_t len){
+    char buf[52], *bptr = buf;
+    for(uint16_t l = 0; l < len; ++l, ++arr){
+        for(int16_t j = 1; j > -1; --j){
+            register uint8_t half = (*arr >> (4*j)) & 0x0f;
+            if(half < 10) *bptr++ = half + '0';
+            else *bptr++ = half - 10 + 'a';
+        }
+        if(l % 16 == 15){
+            *bptr++ = '\n';
+            *bptr = 0;
+            sendfun(buf);
+            bptr = buf;
+        }else *bptr++ = ' ';
+    }
+    if(bptr != buf){
+        *bptr++ = '\n';
+        *bptr = 0;
+        sendfun(buf);
+    }
+}
+
+/**
+ * @brief _2str - convert value into string buffer
+ * @param val - |value|
+ * @param minus - ==0 if value > 0
+ * @return buffer with number
+ */
+static char *_2str(uint32_t  val, uint8_t minus){
+    static char strbuf[12];
+    char *bufptr = &strbuf[11];
+    *bufptr = 0;
+    if(!val){
+        *(--bufptr) = '0';
+    }else{
+        while(val){
+            uint32_t x = val / 10;
+            *(--bufptr) = (val - 10*x) + '0';
+            val = x;
+            //*(--bufptr) = val % 10 + '0';
+            //val /= 10;
+        }
+    }
+    if(minus) *(--bufptr) = '-';
+    return bufptr;
+}
+
+// return string with number `val`
+char *u2str(uint32_t val){
+    return _2str(val, 0);
+}
+char *i2str(int32_t i){
+    uint8_t minus = 0;
+    uint32_t val;
+    if(i < 0){
+        minus = 1;
+        val = -i;
+    }else val = i;
+    return _2str(val, minus);
+}
+
+/**
+ * @brief uhex2str - print 32bit unsigned int as hex
+ * @param val - value
+ * @return string with number
+ */
+char *uhex2str(uint32_t val){
+    static char buf[12] = "0x";
+    int npos = 2;
+    uint8_t *ptr = (uint8_t*)&val + 3;
+    int8_t i, j, z=1;
+    for(i = 0; i < 4; ++i, --ptr){
+        if(*ptr == 0){ // omit leading zeros
+            if(i == 3) z = 0;
+            if(z) continue;
+        }
+        else z = 0;
+        for(j = 1; j > -1; --j){
+            uint8_t half = (*ptr >> (4*j)) & 0x0f;
+            if(half < 10) buf[npos++] = half + '0';
+            else buf[npos++] = half - 10 + 'a';
+        }
+    }
+    buf[npos] = 0;
+    return buf;
+}
+
+/**
+ * @brief omit_spaces - eliminate leading spaces and other trash in string
+ * @param buf - string
+ * @return - pointer to first character in `buf` > ' '
+ */
+const char *omit_spaces(const char *buf){
+    while(*buf){
+        if(*buf > ' ') break;
+        ++buf;
+    }
+    return buf;
+}
+
+/**
+ * @brief getdec - read decimal number & return pointer to next non-number symbol
+ * @param buf - string
+ * @param N - number read
+ * @return Next non-number symbol. In case of overflow return `buf` and N==0xffffffff
+ */
+static const char *getdec(const char *buf, uint32_t *N){
+    char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '9'){
+            break;
+        }
+        if(num > 429496729 || (num == 429496729 && c > '5')){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num *= 10;
+        num += c - '0';
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read hexadecimal number (without 0x prefix!)
+static const char *gethex(const char *buf, uint32_t *N){
+    const char *start = buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        uint8_t M = 0;
+        if(c >= '0' && c <= '9'){
+            M = '0';
+        }else if(c >= 'A' && c <= 'F'){
+            M = 'A' - 10;
+        }else if(c >= 'a' && c <= 'f'){
+            M = 'a' - 10;
+        }
+        if(M){
+            if(num & 0xf0000000){ // overflow
+                *N = 0xffffff;
+                return start;
+            }
+            num <<= 4;
+            num += c - M;
+        }else{
+            break;
+        }
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read octal number (without 0 prefix!)
+static const char *getoct(const char *buf, uint32_t *N){
+    const char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '7'){
+            break;
+        }
+        if(num & 0xe0000000){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num <<= 3;
+        num += c - '0';
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read binary number (without b prefix!)
+static const char *getbin(const char *buf, uint32_t *N){
+    const char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '1'){
+            break;
+        }
+        if(num & 0x80000000){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num <<= 1;
+        if(c == '1') num |= 1;
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+
+/**
+ * @brief getnum - read uint32_t from string (dec, hex or bin: 127, 0x7f, 0b1111111)
+ * @param buf - buffer with number and so on
+ * @param N   - the number read
+ * @return pointer to first non-number symbol in buf
+ *      (if it is == buf, there's no number or if *N==0xffffffff there was overflow)
+ */
+const char *getnum(const char *txt, uint32_t *N){
+    const char *nxt = NULL;
+    const char *s = omit_spaces(txt);
+    if(*s == '0'){ // hex, oct or 0
+        if(s[1] == 'x' || s[1] == 'X'){ // hex
+            nxt = gethex(s+2, N);
+            if(nxt == s+2) nxt = (char*)txt;
+        }else if(s[1] > '0'-1 && s[1] < '8'){ // oct
+            nxt = getoct(s+1, N);
+            if(nxt == s+1) nxt = (char*)txt;
+        }else{ // 0
+            nxt = s+1;
+            *N = 0;
+        }
+    }else if(*s == 'b' || *s == 'B'){
+        nxt = getbin(s+1, N);
+        if(nxt == s+1) nxt = (char*)txt;
+    }else{
+        nxt = getdec(s, N);
+        if(nxt == s) nxt = (char*)txt;
+    }
+    return nxt;
+}
+
+// get signed integer
+const char *getint(const char *txt, int32_t *I){
+    const char *s = omit_spaces(txt);
+    int32_t sign = 1;
+    uint32_t U;
+    if(*s == '-'){
+    	sign = -1;
+    	++s;
+    }
+    const char *nxt = getnum(s, &U);
+    if(nxt == s) return txt;
+    if(U & 0x80000000) return txt; // overfull
+    *I = sign * (int32_t)U;
+    return nxt;
+}
diff --git a/F3:F303/InterfaceBoard/strfunc.h b/F3:F303/InterfaceBoard/strfunc.h
new file mode 100644
index 0000000..63da760
--- /dev/null
+++ b/F3:F303/InterfaceBoard/strfunc.h
@@ -0,0 +1,30 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <string.h>
+
+void hexdump(int (*sendfun)(const char *s), uint8_t *arr, uint16_t len);
+const char *u2str(uint32_t val);
+const char *i2str(int32_t i);
+const char *uhex2str(uint32_t val);
+const char *getnum(const char *txt, uint32_t *N);
+const char *omit_spaces(const char *buf);
+const char *getint(const char *txt, int32_t *I);
diff --git a/F3:F303/InterfaceBoard/usb_descr.c b/F3:F303/InterfaceBoard/usb_descr.c
new file mode 100644
index 0000000..3e1a872
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_descr.c
@@ -0,0 +1,210 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "usb_descr.h"
+
+// low/high for uint16_t
+#define L16(x)              (x & 0xff)
+#define H16(x)              (x >> 8)
+
+static const uint8_t USB_DeviceDescriptor[] = {
+    USB_DT_DEVICE_SIZE, // bLength
+    USB_DT_DEVICE, // bDescriptorType
+    L16(bcdUSB), // bcdUSB_L
+    H16(bcdUSB), // bcdUSB_H
+    USB_CLASS_MISC, // bDeviceClass
+    bDeviceSubClass, // bDeviceSubClass
+    bDeviceProtocol, // bDeviceProtocol
+    USB_EP0BUFSZ, // bMaxPacketSize
+    L16(idVendor), // idVendor_L
+    H16(idVendor), // idVendor_H
+    L16(idProduct), // idProduct_L
+    H16(idProduct), // idProduct_H
+    L16(bcdDevice_Ver), // bcdDevice_Ver_L
+    H16(bcdDevice_Ver), // bcdDevice_Ver_H
+    iMANUFACTURER_DESCR, // iManufacturer - indexes of string descriptors in array
+    iPRODUCT_DESCR, // iProduct
+    iSERIAL_DESCR, // iSerial
+    bNumConfigurations // bNumConfigurations
+};
+
+static const uint8_t USB_DeviceQualifierDescriptor[] = {
+    USB_DT_QUALIFIER_SIZE, //bLength
+    USB_DT_QUALIFIER, // bDescriptorType
+    L16(bcdUSB), // bcdUSB_L
+    H16(bcdUSB), // bcdUSB_H
+    USB_CLASS_PER_INTERFACE, // bDeviceClass
+    bDeviceSubClass, // bDeviceSubClass
+    bDeviceProtocol, // bDeviceProtocol
+    USB_EP0BUFSZ, // bMaxPacketSize0
+    bNumConfigurations, // bNumConfigurations
+    0 // Reserved
+};
+
+#define wTotalLength  (USB_DT_CONFIG_SIZE + (bNumInterfaces * USB_DT_INTERFACE_SIZE) + (bTotNumEndpoints * USB_DT_ENDPOINT_SIZE) + (bNumCsInterfaces * USB_DT_CS_INTERFACE_SIZE) - 1)
+
+static const uint8_t USB_ConfigDescriptor[] = {
+    // Configuration Descriptor
+    USB_DT_CONFIG_SIZE, // bLength: Configuration Descriptor size
+    USB_DT_CONFIG, // bDescriptorType: Configuration
+    L16(wTotalLength),   // wTotalLength.L :no of returned bytes
+    H16(wTotalLength), // wTotalLength.H
+    bNumInterfaces, // bNumInterfaces
+    1, // bConfigurationValue: Current configuration value
+    0, // iConfiguration: Index of string descriptor describing the configuration or 0
+    BusPowered, // bmAttributes - Bus powered
+    50, // MaxPower in 2mA units
+    //---------------------------------------------------------------------------
+    // Virtual command Interface Descriptor
+    USB_DT_INTERFACE_SIZE, // bLength: Interface Descriptor size
+    USB_DT_INTERFACE, // bDescriptorType: Interface
+    0, // bInterfaceNumber: Number of Interface
+    0, // bAlternateSetting: Alternate setting
+    1, // bNumEndpoints: one for this
+    USB_CLASS_COMM, // bInterfaceClass
+    2, // bInterfaceSubClass: ACM
+    1, // bInterfaceProtocol: Common AT commands
+    iINTERFACE_DESCR1, // iInterface
+    // ---- CS Interfaces
+    USB_DT_CS_INTERFACE_SIZE, // bLength
+    USB_DT_CS_INTERFACE, // bDescriptorType: CS_INTERFACE
+    0, // bDescriptorSubtype: Header Func Desc
+    0x10, // bcdCDC: spec release number
+    1, // bDataInterface
+    USB_DT_CS_INTERFACE_SIZE, // bLength
+    USB_DT_CS_INTERFACE, // bDescriptorType: CS_INTERFACE
+    1, // bDescriptorSubtype: Call Management Func Desc
+    0, // bmCapabilities: D0+D1
+    1, // bDataInterface
+    USB_DT_CS_INTERFACE_SIZE-1, // bLength
+    USB_DT_CS_INTERFACE, // bDescriptorType: CS_INTERFACE
+    2, // bDescriptorSubtype: Abstract Control Management desc
+    2, // bmCapabilities
+    USB_DT_CS_INTERFACE_SIZE, // bLength
+    USB_DT_CS_INTERFACE, // bDescriptorType: CS_INTERFACE
+    6, // bDescriptorSubtype: Union func desc
+    0, // bMasterInterface: Communication class interface
+    1, // bSlaveInterface0: Data Class Interface
+    // Virtual endpoint 1 Descriptor
+    USB_DT_ENDPOINT_SIZE, // bLength: Endpoint Descriptor size
+    USB_DT_ENDPOINT, // bDescriptorType: Endpoint
+    0x8A, // bEndpointAddress IN10
+    USB_BM_ATTR_INTERRUPT, // bmAttributes: Interrupt
+    L16(USB_EP1BUFSZ), // wMaxPacketSize LO
+    H16(USB_EP1BUFSZ), // wMaxPacketSize HI
+    0x10, // bInterval: 16ms
+    //---------------------------------------------------------------------------
+    // Data interface
+    USB_DT_INTERFACE_SIZE, // bLength: Interface Descriptor size
+    USB_DT_INTERFACE, // bDescriptorType: Interface
+    1, // bInterfaceNumber: Number of Interface
+    0, // bAlternateSetting: Alternate setting
+    2, // bNumEndpoints: in and out
+    USB_CLASS_DATA, // bInterfaceClass
+    2, // bInterfaceSubClass: ACM
+    0, // bInterfaceProtocol
+    0, // iInterface
+    //Endpoint IN1 Descriptor
+    USB_DT_ENDPOINT_SIZE, // bLength: Endpoint Descriptor size
+    USB_DT_ENDPOINT, // bDescriptorType: Endpoint
+    0x81, // bEndpointAddress: IN1
+    USB_BM_ATTR_BULK, // bmAttributes: Bulk
+    L16(USB_TXBUFSZ), // wMaxPacketSize LO
+    H16(USB_TXBUFSZ), // wMaxPacketSize HI
+    0, // bInterval: ignore for Bulk transfer
+    // Endpoint OUT1 Descriptor
+    USB_DT_ENDPOINT_SIZE, // bLength: Endpoint Descriptor size
+    USB_DT_ENDPOINT, // bDescriptorType: Endpoint
+    0x01, // bEndpointAddress: OUT1
+    USB_BM_ATTR_BULK, // bmAttributes: Bulk
+    L16(USB_RXBUFSZ), // wMaxPacketSize LO
+    H16(USB_RXBUFSZ), // wMaxPacketSize HI
+    0, // bInterval: ignore for Bulk transfer
+
+};
+
+//const uint8_t HID_ReportDescriptor[];
+
+_USB_LANG_ID_(LD, LANG_US);
+_USB_STRING_(SD, u"0.0.1");
+_USB_STRING_(MD, u"eddy@sao.ru");
+_USB_STRING_(PD, u"USB-CDC");
+_USB_STRING_(ID, u"usbcdc");
+
+static const void* const StringDescriptor[iDESCR_AMOUNT] = {
+    [iLANGUAGE_DESCR] = &LD,
+    [iMANUFACTURER_DESCR] = &MD,
+    [iPRODUCT_DESCR] = &PD,
+    [iSERIAL_DESCR] = &SD,
+    [iINTERFACE_DESCR1] = &ID
+};
+
+static void wr0(const uint8_t *buf, uint16_t size, uint16_t askedsize){
+    if(askedsize < size) size = askedsize; // shortened request
+    if(size < USB_EP0BUFSZ){
+        EP_WriteIRQ(0, buf, size);
+        return;
+    }
+    while(size){
+        uint16_t l = size;
+        if(l > USB_EP0BUFSZ) l = USB_EP0BUFSZ;
+        EP_WriteIRQ(0, buf, l);
+        buf += l;
+        size -= l;
+        uint8_t needzlp = (l == USB_EP0BUFSZ) ? 1 : 0;
+        if(size || needzlp){ // send last data buffer
+            uint16_t epstatus = KEEP_DTOG(USB->EPnR[0]);
+            // keep DTOGs, clear CTR_RX,TX, set TX VALID, leave stat_Rx
+            USB->EPnR[0] = (epstatus & ~(USB_EPnR_CTR_RX|USB_EPnR_CTR_TX|USB_EPnR_STAT_RX))
+                           ^ USB_EPnR_STAT_TX;
+            uint32_t ctr = 1000000;
+            while(--ctr && (USB->ISTR & USB_ISTR_CTR) == 0){IWDG->KR = IWDG_REFRESH;};
+            if((USB->ISTR & USB_ISTR_CTR) == 0){
+                return;
+            }
+            if(needzlp) EP_WriteIRQ(0, NULL, 0);
+        }
+    }
+}
+
+void get_descriptor(config_pack_t *pack){
+    uint8_t descrtype = pack->wValue >> 8,
+        descridx = pack->wValue & 0xff;
+    switch(descrtype){
+        case DEVICE_DESCRIPTOR:
+            wr0(USB_DeviceDescriptor, sizeof(USB_DeviceDescriptor), pack->wLength);
+            break;
+        case CONFIGURATION_DESCRIPTOR:
+            wr0(USB_ConfigDescriptor, sizeof(USB_ConfigDescriptor), pack->wLength);
+            break;
+        case STRING_DESCRIPTOR:
+            if(descridx < iDESCR_AMOUNT){
+                wr0((const uint8_t *)StringDescriptor[descridx], *((uint8_t*)StringDescriptor[descridx]), pack->wLength);
+            }else{
+                EP_WriteIRQ(0, NULL, 0);
+            }
+            break;
+        case DEVICE_QUALIFIER_DESCRIPTOR:
+            wr0(USB_DeviceQualifierDescriptor, sizeof(USB_DeviceQualifierDescriptor), pack->wLength);
+            break;
+       /* case HID_REPORT_DESCRIPTOR:
+            wr0(HID_ReportDescriptor, sizeof(HID_ReportDescriptor), pack->wLength);
+            break;*/
+        default:
+            break;
+    }
+}
diff --git a/F3:F303/InterfaceBoard/usb_descr.h b/F3:F303/InterfaceBoard/usb_descr.h
new file mode 100644
index 0000000..39eeb76
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_descr.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <stdint.h>
+
+#include "usb_lib.h"
+
+// definition of parts common for USB_DeviceDescriptor & USB_DeviceQualifierDescriptor
+// bcdUSB: 1.10
+#define bcdUSB              0x0110
+// Class - Misc (EF), subclass - common (2), protocol - interface association descr (1)
+#define bDeviceSubClass     0x02
+#define bDeviceProtocol     0x01
+#define idVendor            0x0483
+#define idProduct           0x5740
+#define bcdDevice_Ver       0x0200
+#define bNumConfigurations  1
+
+// amount of interfaces and endpoints (except 0) used
+#define bNumInterfaces      2
+#define bTotNumEndpoints    3
+#define bNumCsInterfaces    4
+
+// amount of interfaces
+#define InterfacesAmount    7
+#define ISerial0            0
+#define ICFG                0
+#define ISerial1            1
+#define ISerial2            2
+#define ISerial3            3
+#define ISerial4            4
+#define ISPI                5
+#define ICAN                6
+
+// powered
+#define BusPowered          (1<<7)
+#define SelfPowered         (1<<6)
+#define RemoteWakeup        (1<<5)
+
+// buffer sizes
+// for USB FS EP0 buffers are from 8 to 64 bytes long
+#define USB_EP0BUFSZ    64
+#define USB_EP1BUFSZ    10
+// Rx/Tx EPs
+#define USB_RXBUFSZ     64
+#define USB_TXBUFSZ     64
+
+// string descriptors
+enum{
+    iLANGUAGE_DESCR,
+    iMANUFACTURER_DESCR,
+    iPRODUCT_DESCR,
+    iSERIAL_DESCR,
+    iINTERFACE_DESCR1,
+    iDESCR_AMOUNT
+};
+
+void get_descriptor(config_pack_t *pack);
diff --git a/F3:F303/InterfaceBoard/usb_dev.c b/F3:F303/InterfaceBoard/usb_dev.c
new file mode 100644
index 0000000..8d61eee
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_dev.c
@@ -0,0 +1,249 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+
+#include "ringbuffer.h"
+#include "usb_descr.h"
+#include "usb_dev.h"
+
+// Class-Specific Control Requests
+#define SEND_ENCAPSULATED_COMMAND       0x00    // unused
+#define GET_ENCAPSULATED_RESPONSE       0x01    // unused
+#define SET_COMM_FEATURE                0x02    // unused
+#define GET_COMM_FEATURE                0x03    // unused
+#define CLEAR_COMM_FEATURE              0x04    // unused
+#define SET_LINE_CODING                 0x20
+#define GET_LINE_CODING                 0x21
+#define SET_CONTROL_LINE_STATE          0x22
+#define SEND_BREAK                      0x23
+
+// control line states
+#define CONTROL_DTR                     0x01
+#define CONTROL_RTS                     0x02
+
+// inbuf overflow when receiving
+static volatile uint8_t bufovrfl = 0;
+
+// receive buffer: hold data until chkin() call
+static uint8_t volatile rcvbuf[USB_RXBUFSZ];
+static uint8_t volatile rcvbuflen = 0;
+// line coding
+usb_LineCoding WEAK lineCoding = {115200, 0, 0, 8};
+// CDC configured and ready to use
+volatile uint8_t CDCready = 0;
+
+// ring buffers for incoming and outgoing data
+static uint8_t obuf[RBOUTSZ], ibuf[RBINSZ];
+static volatile ringbuffer rbout = {.data = obuf, .length = RBOUTSZ, .head = 0, .tail = 0};
+static volatile ringbuffer rbin = {.data = ibuf, .length = RBINSZ, .head = 0, .tail = 0};
+// last send data size
+static volatile int lastdsz = 0;
+
+static void chkin(){
+    if(bufovrfl) return; // allow user to know that previous buffer was overflowed and cleared
+    if(!rcvbuflen) return;
+    int w = RB_write((ringbuffer*)&rbin, (uint8_t*)rcvbuf, rcvbuflen);
+    if(w < 0){
+        return;
+    }
+    if(w != rcvbuflen) bufovrfl = 1;
+    rcvbuflen = 0;
+    uint16_t status = KEEP_DTOG(USB->EPnR[1]); // don't change DTOG
+    USB->EPnR[1] = (status & ~(USB_EPnR_STAT_TX|USB_EPnR_CTR_RX)) ^ USB_EPnR_STAT_RX; // prepare to get next data portion
+}
+
+// called from transmit EP to send next data portion or by user - when new transmission starts
+static void send_next(){
+    uint8_t usbbuff[USB_TXBUFSZ];
+    int buflen = RB_read((ringbuffer*)&rbout, (uint8_t*)usbbuff, USB_TXBUFSZ);
+    if(buflen == 0){
+        if(lastdsz == 64) EP_Write(1, NULL, 0); // send ZLP after 64 bits packet when nothing more to send
+        lastdsz = 0;
+        return;
+    }else if(buflen < 0){
+        lastdsz = 0;
+        return;
+    }
+    EP_Write(1, (uint8_t*)usbbuff, buflen);
+    lastdsz = buflen;
+}
+
+// data IN/OUT handler
+static void rxtx_handler(){
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[1]);
+    if(RX_FLAG(epstatus)){ // receive data
+        if(rcvbuflen){
+            bufovrfl = 1; // lost last data
+            rcvbuflen = 0;
+        }
+        rcvbuflen = EP_Read(1, (uint8_t*)rcvbuf);
+        USB->EPnR[1] = epstatus & ~(USB_EPnR_CTR_RX | USB_EPnR_STAT_RX | USB_EPnR_STAT_TX); // keep RX in STALL state until read data
+        chkin(); // try to write current data into RXbuf if it's not busy
+    }else{ // tx successfull
+        USB->EPnR[1] = (epstatus & ~(USB_EPnR_CTR_TX | USB_EPnR_STAT_TX)) ^ USB_EPnR_STAT_RX;
+        send_next();
+    }
+}
+
+// weak handlers: change them somewhere else if you want to setup USART
+// SET_LINE_CODING
+void WEAK linecoding_handler(usb_LineCoding *lc){
+    lineCoding = *lc;
+}
+
+// SET_CONTROL_LINE_STATE
+void WEAK clstate_handler(uint16_t val){
+    CDCready = val; // CONTROL_DTR | CONTROL_RTS -> interface connected; 0 -> disconnected
+}
+
+// SEND_BREAK
+void WEAK break_handler(){
+    CDCready = 0;
+}
+
+
+// USB is configured: setup endpoints
+void set_configuration(){
+    EP_Init(1, EP_TYPE_BULK, USB_TXBUFSZ, USB_RXBUFSZ, rxtx_handler); // IN1 and OUT1
+}
+
+// PL2303 CLASS request
+void usb_class_request(config_pack_t *req, uint8_t *data, uint16_t datalen){
+    uint8_t recipient = REQUEST_RECIPIENT(req->bmRequestType);
+    uint8_t dev2host = (req->bmRequestType & 0x80) ? 1 : 0;
+    switch(recipient){
+        case REQ_RECIPIENT_INTERFACE:
+            switch(req->bRequest){
+                case SET_LINE_CODING:
+                    if(!data || !datalen) break; // wait for data
+                    if(datalen == sizeof(usb_LineCoding))
+                        linecoding_handler((usb_LineCoding*)data);
+                break;
+                case GET_LINE_CODING:
+                    EP_WriteIRQ(0, (uint8_t*)&lineCoding, sizeof(lineCoding));
+                break;
+                case SET_CONTROL_LINE_STATE:
+                    clstate_handler(req->wValue);
+                break;
+                case SEND_BREAK:
+                    break_handler();
+                break;
+                default:
+                    break;
+            }
+        break;
+        default:
+            if(dev2host) EP_WriteIRQ(0, NULL, 0);
+    }
+    if(!dev2host) EP_WriteIRQ(0, NULL, 0);
+}
+
+// blocking send full content of ring buffer
+int USB_sendall(){
+    while(lastdsz > 0){
+        if(!CDCready) return FALSE;
+    }
+    return TRUE;
+}
+
+// put `buf` into queue to send
+int USB_send(const uint8_t *buf, int len){
+    if(!buf || !CDCready || !len) return FALSE;
+    while(len){
+        IWDG->KR = IWDG_REFRESH;
+        int l = RB_datalen((ringbuffer*)&rbout);
+        if(l < 0) continue;
+        int portion = rbout.length - 1 - l;
+        if(portion < 1){
+            if(lastdsz == 0) send_next();
+            continue;
+        }
+        if(portion > len) portion = len;
+        int a = RB_write((ringbuffer*)&rbout, buf, portion);
+        if(a > 0){
+            len -= a;
+            buf += a;
+        } else if (a < 0) continue; // do nothing if buffer is in reading state
+        if(lastdsz == 0) send_next(); // need to run manually - all data sent, so no IRQ on IN
+    }
+    return TRUE;
+}
+
+int USB_putbyte(uint8_t byte){
+    if(!CDCready) return FALSE;
+    int l = 0;
+    while((l = RB_write((ringbuffer*)&rbout, &byte, 1)) != 1){
+        if(l < 0) continue;
+    }
+    if(lastdsz == 0) send_next(); // need to run manually - all data sent, so no IRQ on IN
+    return TRUE;
+}
+
+int USB_sendstr(const char *string){
+    if(!string || !CDCready) return FALSE;
+    int len = 0;
+    const char *b = string;
+    while(*b++) ++len;
+    if(!len) return FALSE;
+    return USB_send((const uint8_t*)string, len);
+}
+
+/**
+ * @brief USB_receive - get binary data from receiving ring-buffer
+ * @param buf (i) - buffer for received data
+ * @param len - length of `buf`
+ * @return amount of received bytes (negative, if overfull happened)
+ */
+int USB_receive(uint8_t *buf, int len){
+    chkin();
+    if(bufovrfl){
+        while(1 != RB_clearbuf((ringbuffer*)&rbin));
+        bufovrfl = 0;
+        return -1;
+    }
+    int sz = RB_read((ringbuffer*)&rbin, buf, len);
+    if(sz < 0) return 0; // buffer in writting state
+    return sz;
+}
+
+/**
+ * @brief USB_receivestr - get string up to '\n' and replace '\n' with 0
+ * @param buf - receiving buffer
+ * @param len - its length
+ * @return strlen or negative value indicating overflow (if so, string won't be ends with 0 and buffer should be cleared)
+ */
+int USB_receivestr(char *buf, int len){
+    chkin();
+    if(bufovrfl){
+        while(1 != RB_clearbuf((ringbuffer*)&rbin));
+        bufovrfl = 0;
+        return -1;
+    }
+    int l = RB_readto((ringbuffer*)&rbin, '\n', (uint8_t*)buf, len);
+    if(l < 1){
+        if(rbin.length == RB_datalen((ringbuffer*)&rbin)){ // buffer is full but no '\n' found
+            while(1 != RB_clearbuf((ringbuffer*)&rbin));
+            return -1;
+        }
+        return 0;
+    }
+    if(l == 0) return 0;
+    buf[l-1] = 0; // replace '\n' with strend
+    return l;
+}
+
diff --git a/F3:F303/InterfaceBoard/usb_dev.h b/F3:F303/InterfaceBoard/usb_dev.h
new file mode 100644
index 0000000..1f8003c
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_dev.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <stm32f3.h>
+#include "usb_lib.h"
+
+typedef struct {
+    uint32_t dwDTERate;
+    uint8_t bCharFormat;
+#define USB_CDC_1_STOP_BITS   0
+#define USB_CDC_1_5_STOP_BITS 1
+#define USB_CDC_2_STOP_BITS   2
+    uint8_t bParityType;
+#define USB_CDC_NO_PARITY     0
+#define USB_CDC_ODD_PARITY    1
+#define USB_CDC_EVEN_PARITY   2
+#define USB_CDC_MARK_PARITY   3
+#define USB_CDC_SPACE_PARITY  4
+    uint8_t bDataBits;
+} __attribute__ ((packed)) usb_LineCoding;
+
+extern usb_LineCoding lineCoding;
+extern volatile uint8_t CDCready;
+
+void break_handler();
+void clstate_handler(uint16_t val);
+void linecoding_handler(usb_LineCoding *lc);
+
+
+// sizes of ringbuffers for outgoing and incoming data
+#define RBOUTSZ     (1024)
+#define RBINSZ      (1024)
+
+#define newline()   USB_putbyte('\n')
+#define USND(s)     do{USB_sendstr(s); USB_putbyte('\n');}while(0)
+
+int USB_sendall();
+int USB_send(const uint8_t *buf, int len);
+int USB_putbyte(uint8_t byte);
+int USB_sendstr(const char *string);
+int USB_receive(uint8_t *buf, int len);
+int USB_receivestr(char *buf, int len);
diff --git a/F3:F303/InterfaceBoard/usb_lib.c b/F3:F303/InterfaceBoard/usb_lib.c
new file mode 100644
index 0000000..9f01a8f
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_lib.c
@@ -0,0 +1,368 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdint.h>
+
+#include "usb_lib.h"
+#include "usb_descr.h"
+#include "usb_dev.h"
+
+static ep_t endpoints[STM32ENDPOINTS];
+
+static uint16_t USB_Addr = 0;
+static uint8_t setupdatabuf[EP0DATABUF_SIZE];
+static config_pack_t *setup_packet = (config_pack_t*) setupdatabuf;
+volatile uint8_t usbON = 0; // device is configured and active
+
+static uint16_t configuration = 0; // reply for GET_CONFIGURATION (==1 if configured)
+static inline void std_d2h_req(){
+    uint16_t st = 0;
+    switch(setup_packet->bRequest){
+        case GET_DESCRIPTOR:
+            get_descriptor(setup_packet);
+        break;
+        case GET_STATUS:
+            EP_WriteIRQ(0, (uint8_t *)&st, 2); // send status: Bus Powered
+        break;
+        case GET_CONFIGURATION:
+            EP_WriteIRQ(0, (uint8_t*)&configuration, 1);
+        break;
+        default:
+            EP_WriteIRQ(0, NULL, 0);
+        break;
+    }
+}
+
+static inline void std_h2d_req(){
+    switch(setup_packet->bRequest){
+        case SET_ADDRESS:
+            // new address will be assigned later - after  acknowlegement or request to host
+            USB_Addr = setup_packet->wValue;
+        break;
+        case SET_CONFIGURATION:
+            // Now device configured
+            configuration = setup_packet->wValue;
+            set_configuration();
+            usbON = 1;
+        break;
+        default:
+        break;
+    }
+}
+
+void WEAK usb_standard_request(){
+    uint8_t recipient = REQUEST_RECIPIENT(setup_packet->bmRequestType);
+    uint8_t dev2host = (setup_packet->bmRequestType & 0x80) ? 1 : 0;
+    switch(recipient){
+        case REQ_RECIPIENT_DEVICE:
+            if(dev2host){
+                std_d2h_req();
+            }else{
+                std_h2d_req();
+            }
+        break;
+        case REQ_RECIPIENT_INTERFACE:
+            if(dev2host && setup_packet->bRequest == GET_DESCRIPTOR){
+                get_descriptor(setup_packet);
+            }
+        break;
+        case REQ_RECIPIENT_ENDPOINT:
+            if(setup_packet->bRequest == CLEAR_FEATURE){
+            }else{ /* wrong */ }
+        break;
+        default:
+        break;
+    }
+    if(!dev2host) EP_WriteIRQ(0, NULL, 0);
+}
+
+void WEAK usb_class_request(config_pack_t *req, uint8_t _U_ *data, uint16_t _U_ datalen){
+    switch(req->bRequest){
+        case GET_INTERFACE:
+        break;
+        case SET_CONFIGURATION: // set featuring by req->wValue
+        break;
+        default:
+            break;
+    }
+    if(0 == (setup_packet->bmRequestType & 0x80)) // host2dev
+        EP_WriteIRQ(0, NULL, 0);
+}
+
+void WEAK usb_vendor_request(config_pack_t _U_ *packet, uint8_t _U_ *data, uint16_t _U_ datalen){
+    if(0 == (setup_packet->bmRequestType & 0x80)) // host2dev
+        EP_WriteIRQ(0, NULL, 0);
+}
+
+/*
+bmRequestType: 76543210
+7    direction: 0 - host->device, 1 - device->host
+65   type: 0 - standard, 1 - class, 2 - vendor
+4..0 getter: 0 - device, 1 - interface, 2 - endpoint, 3 - other
+*/
+/**
+ * Endpoint0 (control) handler
+ */
+static void EP0_Handler(){
+    uint8_t ep0dbuflen = 0;
+    uint8_t ep0databuf[EP0DATABUF_SIZE];
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[0]); // EP0R on input -> return this value after modifications
+    int rxflag = RX_FLAG(epstatus);
+    //if(rxflag){  }
+    // check direction
+    if(USB->ISTR & USB_ISTR_DIR){ // OUT interrupt - receive data, CTR_RX==1 (if CTR_TX == 1 - two pending transactions: receive following by transmit)
+            if(epstatus & USB_EPnR_SETUP){ // setup packet -> copy data to conf_pack
+                EP_Read(0, setupdatabuf);
+                // interrupt handler will be called later
+            }else if(epstatus & USB_EPnR_CTR_RX){ // data packet -> push received data to ep0databuf
+                //if(endpoints[0].rx_cnt){ }
+                ep0dbuflen = EP_Read(0, ep0databuf);
+            }
+    }
+    if(rxflag){
+        uint8_t reqtype = REQUEST_TYPE(setup_packet->bmRequestType);
+        switch(reqtype){
+            case REQ_TYPE_STANDARD:
+                if(SETUP_FLAG(epstatus)){
+                    usb_standard_request();
+                }else{ }
+                break;
+            case REQ_TYPE_CLASS:
+                usb_class_request(setup_packet, ep0databuf, ep0dbuflen);
+                break;
+            case REQ_TYPE_VENDOR:
+                usb_vendor_request(setup_packet, ep0databuf, ep0dbuflen);
+                break;
+            default:
+                EP_WriteIRQ(0, NULL, 0);
+                break;
+        }
+    }
+    if(TX_FLAG(epstatus)){
+        // now we can change address after enumeration
+        if ((USB->DADDR & USB_DADDR_ADD) != USB_Addr){
+            USB->DADDR = USB_DADDR_EF | USB_Addr;
+            usbON = 0;
+        }
+    }
+    //epstatus = KEEP_DTOG(USB->EPnR[0]);
+    if(rxflag) epstatus ^= USB_EPnR_STAT_TX; // start ZLP or data transmission
+    else epstatus &= ~USB_EPnR_STAT_TX; // or leave unchanged
+    // keep DTOGs, clear CTR_RX,TX, set RX VALID
+    USB->EPnR[0] = (epstatus & ~(USB_EPnR_CTR_RX|USB_EPnR_CTR_TX)) ^ USB_EPnR_STAT_RX;
+}
+
+/**
+ * Write data to EP buffer (called from IRQ handler)
+ * @param number - EP number
+ * @param *buf - array with data
+ * @param size - its size
+ */
+void EP_WriteIRQ(uint8_t number, const uint8_t *buf, uint16_t size){
+    if(size > endpoints[number].txbufsz) size = endpoints[number].txbufsz;
+    uint16_t N2 = (size + 1) >> 1;
+    // the buffer is 16-bit, so we should copy data as it would be uint16_t
+    uint16_t *buf16 = (uint16_t *)buf;
+#if defined USB1_16
+    // very bad: what if `size` is odd?
+    uint32_t *out = (uint32_t *)endpoints[number].tx_buf;
+    for(int i = 0; i < N2; ++i, ++out){
+        *out = buf16[i];
+    }
+#elif defined USB2_16
+    // use memcpy instead?
+    for(int i = 0; i < N2; i++){
+        endpoints[number].tx_buf[i] = buf16[i];
+    }
+#else
+#error "Define USB1_16 or USB2_16"
+#endif
+    USB_BTABLE->EP[number].USB_COUNT_TX = size;
+}
+
+/**
+ * Write data to EP buffer (called outside IRQ handler)
+ * @param number - EP number
+ * @param *buf - array with data
+ * @param size - its size
+ */
+void EP_Write(uint8_t number, const uint8_t *buf, uint16_t size){
+    EP_WriteIRQ(number, buf, size);
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[number]);
+    // keep DTOGs and RX stat, clear CTR_TX & set TX VALID to start transmission
+    USB->EPnR[number] = (epstatus & ~(USB_EPnR_CTR_TX | USB_EPnR_STAT_RX)) ^ USB_EPnR_STAT_TX;
+}
+
+/*
+ * Copy data from EP buffer into user buffer area
+ * @param *buf - user array for data
+ * @return amount of data read
+ */
+int EP_Read(uint8_t number, uint8_t *buf){
+    int sz = endpoints[number].rx_cnt;
+    if(!sz) return 0;
+    endpoints[number].rx_cnt = 0;
+#if defined USB1_16
+    int n = (sz + 1) >> 1;
+    uint32_t *in = (uint32_t*)endpoints[number].rx_buf;
+    uint16_t *out = (uint16_t*)buf;
+    for(int i = 0; i < n; ++i, ++in)
+        out[i] = *(uint16_t*)in;
+#elif defined USB2_16
+    // use memcpy instead?
+    for(int i = 0; i < sz; ++i)
+        buf[i] = endpoints[number].rx_buf[i];
+#else
+#error "Define USB1_16 or USB2_16"
+#endif
+    return sz;
+}
+
+
+static uint16_t lastaddr = LASTADDR_DEFAULT;
+/**
+ * Endpoint initialisation
+ * @param number - EP num (0...7)
+ * @param type - EP type (EP_TYPE_BULK, EP_TYPE_CONTROL, EP_TYPE_ISO, EP_TYPE_INTERRUPT)
+ * @param txsz - transmission buffer size @ USB/CAN buffer
+ * @param rxsz - reception buffer size @ USB/CAN buffer
+ * @param uint16_t (*func)(ep_t *ep) - EP handler function
+ * @return 0 if all OK
+ */
+int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, void (*func)(ep_t ep)){
+    if(number >= STM32ENDPOINTS) return 4; // out of configured amount
+    if(txsz > USB_BTABLE_SIZE/ACCESSZ || rxsz > USB_BTABLE_SIZE/ACCESSZ) return 1; // buffer too large
+    if(lastaddr + txsz + rxsz >= USB_BTABLE_SIZE/ACCESSZ) return 2; // out of btable
+    USB->EPnR[number] = (type << 9) | (number & USB_EPnR_EA);
+    USB->EPnR[number] ^= USB_EPnR_STAT_RX | USB_EPnR_STAT_TX_1;
+    if(rxsz & 1) return 3; // wrong rx buffer size
+    uint16_t countrx = 0;
+    if(rxsz < 64) countrx = rxsz / 2;
+    else{
+        if(rxsz & 0x1f) return 3; // should be multiple of 32
+        countrx = 31 + rxsz / 32;
+    }
+    USB_BTABLE->EP[number].USB_ADDR_TX = lastaddr;
+    endpoints[number].tx_buf = (uint16_t *)(USB_BTABLE_BASE + lastaddr * ACCESSZ);
+    endpoints[number].txbufsz = txsz;
+    lastaddr += txsz;
+    USB_BTABLE->EP[number].USB_COUNT_TX = 0;
+    USB_BTABLE->EP[number].USB_ADDR_RX = lastaddr;
+    endpoints[number].rx_buf = (uint8_t *)(USB_BTABLE_BASE + lastaddr * ACCESSZ);
+    lastaddr += rxsz;
+    USB_BTABLE->EP[number].USB_COUNT_RX = countrx << 10;
+    endpoints[number].func = func;
+    return 0;
+}
+
+// standard IRQ handler
+void USB_IRQ(){
+    uint32_t CNTR = USB->CNTR;
+    USB->CNTR = 0;
+    if(USB->ISTR & USB_ISTR_RESET){
+        usbON = 0;
+        // Reinit registers
+        CNTR = USB_CNTR_RESETM | USB_CNTR_CTRM | USB_CNTR_SUSPM;
+        // Endpoint 0 - CONTROL
+        // ON USB LS size of EP0 may be 8 bytes, but on FS it should be 64 bytes!
+        lastaddr = LASTADDR_DEFAULT;
+        // clear address, leave only enable bit
+        USB->DADDR = USB_DADDR_EF;
+        USB->ISTR = ~USB_ISTR_RESET;
+        if(EP_Init(0, EP_TYPE_CONTROL, USB_EP0BUFSZ, USB_EP0BUFSZ, EP0_Handler)){
+            return;
+        };
+    }
+    if(USB->ISTR & USB_ISTR_CTR){
+        // EP number
+        uint8_t n = USB->ISTR & USB_ISTR_EPID;
+        // copy received bytes amount
+        endpoints[n].rx_cnt = USB_BTABLE->EP[n].USB_COUNT_RX & 0x3FF; // low 10 bits is counter
+        // call EP handler
+        if(endpoints[n].func) endpoints[n].func();
+    }
+    if(USB->ISTR & USB_ISTR_WKUP){ // wakeup
+#ifndef STM32F0
+        CNTR &= ~(USB_CNTR_FSUSP | USB_CNTR_LP_MODE | USB_CNTR_WKUPM); // clear suspend flags
+#else
+        CNTR &= ~(USB_CNTR_FSUSP | USB_CNTR_LPMODE | USB_CNTR_WKUPM);
+#endif
+        USB->ISTR = ~USB_ISTR_WKUP;
+    }
+    if(USB->ISTR & USB_ISTR_SUSP){ // suspend -> still no connection, may sleep
+        usbON = 0;
+#ifndef STM32F0
+        CNTR |= USB_CNTR_FSUSP | USB_CNTR_LP_MODE | USB_CNTR_WKUPM;
+#else
+        CNTR |= USB_CNTR_FSUSP | USB_CNTR_LPMODE | USB_CNTR_WKUPM;
+#endif
+        CNTR &= ~(USB_CNTR_SUSPM);
+        USB->ISTR = ~USB_ISTR_SUSP;
+    }
+    USB->CNTR = CNTR; // rewoke interrupts
+}
+
+// here we suppose that all PIN settings done in hw_setup earlier
+void USB_setup(){
+#if defined STM32F3
+    NVIC_DisableIRQ(USB_LP_IRQn);
+    // remap USB LP & Wakeup interrupts to 75 and 76 - works only on pure F303
+    RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN; // enable tacting of SYSCFG
+    SYSCFG->CFGR1 |= SYSCFG_CFGR1_USB_IT_RMP;
+#elif defined STM32F1
+    NVIC_DisableIRQ(USB_LP_CAN1_RX0_IRQn);
+    NVIC_DisableIRQ(USB_HP_CAN1_TX_IRQn);
+#elif defined STM32F0
+    NVIC_DisableIRQ(USB_IRQn);
+    RCC->APB1ENR |= RCC_APB1ENR_CRSEN;
+    RCC->CFGR3 &= ~RCC_CFGR3_USBSW; // reset USB
+    RCC->CR2 |= RCC_CR2_HSI48ON; // turn ON HSI48
+    uint32_t tmout = 16000000;
+    while(!(RCC->CR2 & RCC_CR2_HSI48RDY)){if(--tmout == 0) break;}
+    FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY;
+    CRS->CFGR &= ~CRS_CFGR_SYNCSRC;
+    CRS->CFGR |= CRS_CFGR_SYNCSRC_1; // USB SOF selected as sync source
+    CRS->CR |= CRS_CR_AUTOTRIMEN; // enable auto trim
+    CRS->CR |= CRS_CR_CEN; // enable freq counter & block CRS->CFGR as read-only
+    RCC->CFGR |= RCC_CFGR_SW;
+#endif
+    RCC->APB1ENR |= RCC_APB1ENR_USBEN;
+    //??
+    USB->CNTR   = USB_CNTR_FRES; // Force USB Reset
+    for(uint32_t ctr = 0; ctr < 72000; ++ctr) nop(); // wait >1ms
+    USB->CNTR   = 0;
+    USB->BTABLE = 0;
+    USB->DADDR  = 0;
+    USB->ISTR   = 0;
+    USB->CNTR   = USB_CNTR_RESETM; // allow only reset interrupts
+#if defined STM32F3
+    NVIC_EnableIRQ(USB_LP_IRQn);
+#elif defined STM32F1
+    NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
+#elif defined STM32F0
+    USB->BCDR |= USB_BCDR_DPPU;
+    NVIC_EnableIRQ(USB_IRQn);
+#endif
+}
+
+
+#if defined STM32F3
+void usb_lp_isr() __attribute__ ((alias ("USB_IRQ")));
+#elif defined STM32F1
+void usb_lp_can_rx0_isr() __attribute__ ((alias ("USB_IRQ")));
+#elif defined STM32F0
+void usb_isr() __attribute__ ((alias ("USB_IRQ")));
+#endif
diff --git a/F3:F303/InterfaceBoard/usb_lib.h b/F3:F303/InterfaceBoard/usb_lib.h
new file mode 100644
index 0000000..d55c83f
--- /dev/null
+++ b/F3:F303/InterfaceBoard/usb_lib.h
@@ -0,0 +1,328 @@
+/*
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <stdint.h>
+#include <wchar.h>
+
+#ifndef _U_
+#define _U_         __attribute__((unused))
+#endif
+
+/******************************************************************
+ *             Hardware registers etc                             *
+ *****************************************************************/
+#if defined STM32F0
+#include <stm32f0.h>
+#elif defined STM32F1
+#include <stm32f1.h>
+// there's no this define in standard header
+#define USB_BASE                ((uint32_t)0x40005C00)
+#elif defined STM32F3
+#include <stm32f3.h>
+#endif
+
+// max endpoints number
+#define STM32ENDPOINTS          8
+/**
+ *                 Buffers size definition
+ **/
+
+//  F0 - USB2_16; F1 - USB1_16; F3 - 1/2 depending on series
+#if !defined USB1_16 && !defined USB2_16
+#if defined STM32F0
+#define USB2_16
+#elif defined STM32F1
+#define USB1_16
+#else
+#error "Can't determine USB1_16 or USB2_16, define by hands"
+#endif
+#endif
+
+// BTABLE_SIZE FOR STM32F3:
+// In STM32F303/302xB/C, 512 bytes SRAM is not shared with CAN.
+// In STM32F302x6/x8 and STM32F30xxD/E, 726 bytes dedicated SRAM and 256 bytes shared SRAM with CAN i.e.
+//     1Kbytes dedicated SRAM in case CAN is disabled.
+// remember, that USB_BTABLE_SIZE will be divided by ACCESSZ, so don't divide it twice for 32-bit addressing
+
+#ifdef NOCAN
+#if defined STM32F0
+#define USB_BTABLE_SIZE         1024
+#elif defined STM32F3
+#define USB_BTABLE_SIZE         726
+//#warning "Please, check real buffer size due to docs"
+#else
+#error "define STM32F0 or STM32F3"
+#endif
+#else // !NOCAN: F0/F3 with CAN or F1 (can't simultaneously run CAN and USB)
+#if defined STM32F0
+#define USB_BTABLE_SIZE         768
+#elif defined STM32F3
+#define USB_BTABLE_SIZE         726
+//#warning "Please, check real buffer size due to docs"
+#else // STM32F103: 1024 bytes but with 32-bit addressing
+#define USB_BTABLE_SIZE         1024
+#endif
+#endif // NOCAN
+
+// first 64 bytes of USB_BTABLE are registers!
+
+#define USB_BTABLE_BASE         0x40006000
+#define USB                     ((USB_TypeDef *) USB_BASE)
+
+#ifdef USB_BTABLE
+#undef USB_BTABLE
+#endif
+#define USB_BTABLE              ((USB_BtableDef *)(USB_BTABLE_BASE))
+#define USB_ISTR_EPID           0x0000000F
+#define USB_FNR_LSOF_0          0x00000800
+#define USB_FNR_lSOF_1          0x00001000
+#define USB_LPMCSR_BESL_0       0x00000010
+#define USB_LPMCSR_BESL_1       0x00000020
+#define USB_LPMCSR_BESL_2       0x00000040
+#define USB_LPMCSR_BESL_3       0x00000080
+#define USB_EPnR_CTR_RX         0x00008000
+#define USB_EPnR_DTOG_RX        0x00004000
+#define USB_EPnR_STAT_RX        0x00003000
+#define USB_EPnR_STAT_RX_0      0x00001000
+#define USB_EPnR_STAT_RX_1      0x00002000
+#define USB_EPnR_SETUP          0x00000800
+#define USB_EPnR_EP_TYPE        0x00000600
+#define USB_EPnR_EP_TYPE_0      0x00000200
+#define USB_EPnR_EP_TYPE_1      0x00000400
+#define USB_EPnR_EP_KIND        0x00000100
+#define USB_EPnR_CTR_TX         0x00000080
+#define USB_EPnR_DTOG_TX        0x00000040
+#define USB_EPnR_STAT_TX        0x00000030
+#define USB_EPnR_STAT_TX_0      0x00000010
+#define USB_EPnR_STAT_TX_1      0x00000020
+#define USB_EPnR_EA             0x0000000F
+#define USB_COUNTn_RX_BLSIZE    0x00008000
+#define USB_COUNTn_NUM_BLOCK    0x00007C00
+#define USB_COUNTn_RX           0x0000003F
+
+#define USB_TypeDef USB_TypeDef_custom
+
+typedef struct {
+    __IO uint32_t EPnR[STM32ENDPOINTS];
+    __IO uint32_t RESERVED[STM32ENDPOINTS];
+    __IO uint32_t CNTR;
+    __IO uint32_t ISTR;
+    __IO uint32_t FNR;
+    __IO uint32_t DADDR;
+    __IO uint32_t BTABLE;
+#ifdef STM32F0
+    __IO uint32_t LPMCSR;
+    __IO uint32_t BCDR;
+#endif
+} USB_TypeDef;
+
+// F303 D/E have 2x16 access scheme
+typedef struct{
+#if defined USB2_16
+    __IO uint16_t USB_ADDR_TX;
+    __IO uint16_t USB_COUNT_TX;
+    __IO uint16_t USB_ADDR_RX;
+    __IO uint16_t USB_COUNT_RX;
+#define ACCESSZ (1)
+#define BUFTYPE uint8_t
+#elif defined USB1_16
+    __IO uint32_t USB_ADDR_TX;
+    __IO uint32_t USB_COUNT_TX;
+    __IO uint32_t USB_ADDR_RX;
+    __IO uint32_t USB_COUNT_RX;
+#define ACCESSZ (2)
+#define BUFTYPE uint16_t
+#else
+#error "Define USB1_16 or USB2_16"
+#endif
+} USB_EPDATA_TypeDef;
+
+
+typedef struct{
+    __IO USB_EPDATA_TypeDef EP[STM32ENDPOINTS];
+} USB_BtableDef;
+
+#define EP0DATABUF_SIZE                 (64)
+#define LASTADDR_DEFAULT                (STM32ENDPOINTS * 8)
+
+/******************************************************************
+ *             Defines from usb.h                                 *
+ *****************************************************************/
+
+/*
+ * Device and/or Interface Class codes
+ */
+#define USB_CLASS_PER_INTERFACE         0
+#define USB_CLASS_AUDIO                 1
+#define USB_CLASS_COMM                  2
+#define USB_CLASS_HID                   3
+#define USB_CLASS_PRINTER               7
+#define USB_CLASS_PTP                   6
+#define USB_CLASS_MASS_STORAGE          8
+#define USB_CLASS_HUB                   9
+#define USB_CLASS_DATA                  10
+#define USB_CLASS_MISC                  0xef
+#define USB_CLASS_VENDOR_SPEC           0xff
+
+/*
+ * Descriptor types
+ */
+#define USB_DT_DEVICE                   0x01
+#define USB_DT_CONFIG                   0x02
+#define USB_DT_STRING                   0x03
+#define USB_DT_INTERFACE                0x04
+#define USB_DT_ENDPOINT                 0x05
+#define USB_DT_QUALIFIER                0x06
+#define USB_DT_IAD                      0x0B
+
+#define USB_DT_HID                      0x21
+#define USB_DT_REPORT                   0x22
+#define USB_DT_PHYSICAL                 0x23
+#define USB_DT_CS_INTERFACE             0x24
+#define USB_DT_HUB                      0x29
+
+/*
+ * Descriptor sizes per descriptor type
+ */
+#define USB_DT_DEVICE_SIZE              18
+#define USB_DT_CONFIG_SIZE              9
+#define USB_DT_INTERFACE_SIZE           9
+#define USB_DT_HID_SIZE                 9
+#define USB_DT_ENDPOINT_SIZE            7
+#define USB_DT_QUALIFIER_SIZE           10
+#define USB_DT_CS_INTERFACE_SIZE        5
+#define USB_DT_IAD_SIZE                 8
+
+
+// bmRequestType & 0x80 == dev2host (1) or host2dev (0)
+// recipient: bmRequestType & 0x1f
+#define REQUEST_RECIPIENT(b)    (b & 0x1f)
+#define REQ_RECIPIENT_DEVICE    0
+#define REQ_RECIPIENT_INTERFACE 1
+#define REQ_RECIPIENT_ENDPOINT  2
+#define REQ_RECIPIENT_OTHER     3
+// type: [bmRequestType & 0x60 >> 5]
+#define REQUEST_TYPE(b)         ((b&0x60)>>5)
+#define REQ_TYPE_STANDARD       0
+#define REQ_TYPE_CLASS          1
+#define REQ_TYPE_VENDOR         2
+#define REQ_TYPE_RESERVED       3
+
+
+//#define VENDOR_REQUEST                  0x01
+
+// standard device requests
+#define GET_STATUS                      0x00
+#define CLEAR_FEATURE                   0x01
+#define SET_FEATURE                     0x03
+#define SET_ADDRESS                     0x05
+#define GET_DESCRIPTOR                  0x06
+#define SET_DESCRIPTOR                  0x07
+#define GET_CONFIGURATION               0x08
+#define SET_CONFIGURATION               0x09
+// and some standard interface requests
+#define GET_INTERFACE                   0x0A
+#define SET_INTERFACE                   0x0B
+// and some standard endpoint requests
+#define SYNC_FRAME                      0x0C
+
+// Types of descriptors
+#define DEVICE_DESCRIPTOR               0x01
+#define CONFIGURATION_DESCRIPTOR        0x02
+#define STRING_DESCRIPTOR               0x03
+#define DEVICE_QUALIFIER_DESCRIPTOR     0x06
+#define DEBUG_DESCRIPTOR                0x0a
+#define HID_REPORT_DESCRIPTOR           0x22
+
+// EP types for EP_init
+#define EP_TYPE_BULK                    0x00
+#define EP_TYPE_CONTROL                 0x01
+#define EP_TYPE_ISO                     0x02
+#define EP_TYPE_INTERRUPT               0x03
+
+// EP types for descriptors
+#define USB_BM_ATTR_CONTROL             0x00
+#define USB_BM_ATTR_ISO                 0x01
+#define USB_BM_ATTR_BULK                0x02
+#define USB_BM_ATTR_INTERRUPT           0x03
+
+
+/******************************************************************
+ *                 Other stuff                                    *
+ *****************************************************************/
+
+#define RX_FLAG(epstat)                 (epstat & USB_EPnR_CTR_RX)
+#define TX_FLAG(epstat)                 (epstat & USB_EPnR_CTR_TX)
+#define SETUP_FLAG(epstat)              (epstat & USB_EPnR_SETUP)
+
+// EPnR bits manipulation
+#define KEEP_DTOG_STAT(EPnR)            (EPnR & ~(USB_EPnR_STAT_RX|USB_EPnR_STAT_TX|USB_EPnR_DTOG_RX|USB_EPnR_DTOG_TX))
+#define KEEP_DTOG(EPnR)                 (EPnR & ~(USB_EPnR_DTOG_RX|USB_EPnR_DTOG_TX))
+
+#define LANG_US (uint16_t)0x0409
+
+#define _USB_STRING_(name, str)                  \
+static const struct name \
+{                          \
+        uint8_t  bLength;                       \
+        uint8_t  bDescriptorType;               \
+        uint16_t bString[(sizeof(str) - 2) / 2]; \
+    \
+} \
+name = {sizeof(name), 0x03, str}
+
+#define _USB_LANG_ID_(name, lng_id)     \
+static const struct name \
+{         \
+        uint8_t  bLength;         \
+        uint8_t  bDescriptorType; \
+        uint16_t bString;         \
+    \
+} \
+name = {0x04, 0x03, lng_id}
+
+// EP0 configuration packet
+typedef struct {
+    uint8_t bmRequestType;
+    uint8_t bRequest;
+    uint16_t wValue;
+    uint16_t wIndex;
+    uint16_t wLength;
+} config_pack_t;
+
+// endpoints state
+typedef struct{
+    uint16_t *tx_buf;           // transmission buffer address
+    uint16_t txbufsz;           // transmission buffer size
+    uint8_t *rx_buf;            // reception buffer address
+    void (*func)();             // endpoint action function
+    unsigned rx_cnt  : 10;      // received data counter
+} ep_t;
+
+extern volatile uint8_t usbON;
+
+void USB_setup();
+int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, void (*func)());
+void EP_WriteIRQ(uint8_t number, const uint8_t *buf, uint16_t size);
+void EP_Write(uint8_t number, const uint8_t *buf, uint16_t size);
+int EP_Read(uint8_t number, uint8_t *buf);
+
+// could be [re]defined in usb_dev.c
+extern void usb_class_request(config_pack_t *packet, uint8_t *data, uint16_t datalen);
+extern void usb_vendor_request(config_pack_t *packet, uint8_t *data, uint16_t datalen);
+extern void set_configuration();
diff --git a/F3:F303/InterfaceBoard/version.inc b/F3:F303/InterfaceBoard/version.inc
new file mode 100644
index 0000000..d737cd6
--- /dev/null
+++ b/F3:F303/InterfaceBoard/version.inc
@@ -0,0 +1,2 @@
+#define BUILD_NUMBER "8"
+#define BUILD_DATE "2025-12-28"