diff --git a/F3:F303/InterfaceBoard/Readme.md b/F3:F303/InterfaceBoard/Readme.md
index 49c6019..324814a 100644
--- a/F3:F303/InterfaceBoard/Readme.md
+++ b/F3:F303/InterfaceBoard/Readme.md
@@ -1,15 +1,95 @@
-7 interfaces over USB
-======================
+Multiport board
+====================================
+
+Seven isolated interfaces:
 
 - 1 CAN
 - 3 RS-485
 - 2 or 1 RS-232
-- 1 SSI or 1 RS-422 (in this case 1 RS-232)
+- 1 SSI or 1 RS-422 (in this case only one RS-232)
 
 Inner USB interfaces (IFx):
-1..3 - RS-485 (1..3)
-4 - RS-232 (1)
-5 - RS-232 (2) or RS-485
-6 - CAN
-7 - SSI (over SPI) or configuration interface (if "Config mode" jumper shortened)
+
+1.  RS-485 (1)
+2.  RS-485 (2)
+3.  RS-485 (3)
+4.  RS-232 (1)
+5.  RS-232 (2) or RS-422 (by jumpers)
+6.  CAN
+7.  SSI (over SPI, by jumpers) or configuration interface (if "Config mode" jumper opened)
+
+# Pinout
+
+### Sorted by pin number
+
+| Pin #   | Pin name    | function    | settings      | comment             |
+|---------|-------------|-------------|---------------|---------------------|
+|   1     | (VBAT)      |             |               |                     |
+|   2     | PC13        | NC          |               |                     |
+|   3     | PC14        | NC          |               |                     |
+|   4     | PC15        | NC          |               |                     |
+|   5     | (OSC IN)    |             |               |                     |
+|   6     | (OSC OUT)   |             |               |                     |
+|   7     | (NRST)      |             |               |                     |
+|   8     | PC0         | NC          |               |                     |
+|   9     | PC1         | NC          |               |                     |
+|  10     | PC2         | NC          |               |                     |
+|  11     | PC3         | NC          |               |                     |
+|  12     | (VREF-)     |             |               |                     |
+|  13     | (VREF+)     |             |               |                     |
+|  14     | PA0         | NC          |               |                     |
+|  15     | PA1         | USART2 DE   | AF7           | RS-485 (3) DE       |
+|  16     | PA2         | USART2 TX   | AF7           | RS-485 (3) Tx       |
+|  17     | PA3         | USART2 RX   | AF7           | RS-485 (3) Rx       |
+|  18     | PF4         | NC          |               |                     |
+|  19     | (VDD)       |             |               |                     |
+|  20     | PA4         | NC          |               |                     |
+|  21     | PA5         | SPI1 SCK    | AF5           | SSI CLK             |
+|  22     | PA6         | SPI1 MISO   | AF5           | SSI DAT             |
+|  23     | PA7         | NC          |               |                     |
+|  24     | PC4         | USART1 TX   | AF7           | RS-485 (2) Tx       |
+|  25     | PC5         | USART1 RX   | AF7           | RS-485 (2) Rx       |
+|  26     | PB0         | (USART1 DE) | PP OUT        | RS-485 (2) DE       |
+|  27     | PB1         | NC          |               |                     |
+|  28     | PB2         | NC          |               |                     |
+|  29     | PB10        | USART3 TX   | AF7           | RS-485 (1) Tx       |
+|  30     | PB11        | USART3 RX   | AF7           | RS-485 (1) Rx       |
+|  31     | (VSS)       |             |               |                     |
+|  32     | (VDD)       |             |               |                     |
+|  33     | PB12        | NC          |               |                     |
+|  34     | PB13        | NC          |               |                     |
+|  35     | PB14        | USART3 DE   | AF7           | RS-485 (1) DE       |
+|  36     | PB15        |             |               |                     |
+|  37     | PC6         | NC          |               |                     |
+|  38     | PC7         | NC          |               |                     |
+|  39     | PC8         | NC          |               |                     |
+|  40     | PC9         | NC          |               |                     |
+|  41     | PA8         | NC          |               |                     |
+|  42     | PA9         | (CONF EN)   | PU IN         | Config jumper       |
+|  43     | PA10        | (USB PU)    | PP OUT        | USB pullup          |
+|  44     | PA11        | USB DM      | AF14          |                     |
+|  45     | PA12        | USB DP      | AF14          |                     |
+|  46     | PA13        | SWDIO       | AF0           |                     |
+|  47     | (VSS)       |             |               |                     |
+|  48     | (VDD)       |             |               |                     |
+|  49     | PA14        | SWCLK       | AF0           |                     |
+|  50     | PA15        | NC          |               |                     |
+|  51     | PC10        | UART4 TX    | AF5           | RS-232 (1) Tx       |
+|  52     | PC11        | UART4 RX    | AF5           | RS-232 (1) Rx       |
+|  53     | PC12        | UART5 TX    | AF5           | RS-232(2) / 485 Tx  |
+|  54     | PD2         | UART5 RX    | AF5           | RS-232(2) / 485 Rx  |
+|  55     | PB3         | NC          |               |                     |
+|  56     | PB4         | NC          |               |                     |
+|  57     | PB5         | NC          |               |                     |
+|  58     | PB6         | NC          |               |                     |
+|  59     | PB7         | NC          |               |                     |
+|  60     | (BOOT0)     |             |               |                     |
+|  61     | PB8         | CAN RX      | AF9           |                     |
+|  62     | PB9         | CAN TX      | AF9           |                     |
+|  63     | (VSS)       |             |               |                     |
+|  64     | (VDD)       |             |               |                     |
+
+### Some comments.
+
+### Sorted by ports (with AF numbers).
 
diff --git a/F3:F303/InterfaceBoard/flash.c b/F3:F303/InterfaceBoard/flash.c
index 3088d3b..496eaf2 100644
--- a/F3:F303/InterfaceBoard/flash.c
+++ b/F3:F303/InterfaceBoard/flash.c
@@ -32,15 +32,15 @@ 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",
+        [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},
+    .iIlengths = {22,22,22,22,22,12,12},
 };
 
 int currentconfidx = -1; // index of current configuration
@@ -117,12 +117,12 @@ static int write2flash(const void *start, const void *wrdata, uint32_t stor_size
         *(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");
+            CFGWR("DON'T MATCH!\n");
             ret = 1;
             break;
         }
         if(FLASH->SR & FLASH_SR_PGERR){
-            USB_sendstr("Prog err\n");
+            CFGWR("Prog err\n");
             ret = 1; // program error - meet not 0xffff
             break;
         }
@@ -136,7 +136,7 @@ static int write2flash(const void *start, const void *wrdata, uint32_t stor_size
 static int erase_pageN(int N){
     int ret = 0;
 #ifdef EBUG
-    //CMDWR("Erase page #"); CMDWR(u2str(N)); CMDn();
+    CFGWR("Erase page #"); CFGWRn(u2str(N));
 #endif
     FLASH->AR = (uint32_t)Flash_Data + N*FLASH_blocksize;
     FLASH->CR |= FLASH_CR_STRT;
@@ -158,16 +158,13 @@ int erase_storage(int npage){
         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();
+    CFGWR("FLASH_SIZE="); CFGWR(u2str(FLASH_SIZE));
+    CFGWR("\nflsz="); CFGWR(u2str(flsz));
+    CFGWR("\nend="); CFGWR(u2str(end));
+    CFGWR("\ncurrentconfidx="); CFGWR(u2str(currentconfidx));
+    CFGWR("\nmaxCnum="); CFGWRn(u2str(maxCnum));
 #endif
-*/
     if(end == 0 || end >= FLASH_SIZE) return 1;
     if(npage > -1){ // erase only one page
         if((uint32_t)npage >= end) return 1;
diff --git a/F3:F303/InterfaceBoard/flash.h b/F3:F303/InterfaceBoard/flash.h
index 4f3f564..e8ff614 100644
--- a/F3:F303/InterfaceBoard/flash.h
+++ b/F3:F303/InterfaceBoard/flash.h
@@ -34,8 +34,9 @@
  */
 typedef struct __attribute__((packed, aligned(4))){
     uint16_t userconf_sz;       // "magick number"
+    // we store iInterface "as is"
     uint16_t iInterface[InterfacesAmount][MAX_IINTERFACE_SZ]; // hryunikod!
-    uint8_t iIlengths[InterfacesAmount];
+    uint8_t  iIlengths[InterfacesAmount];
 } user_conf;
 
 extern user_conf the_conf;
diff --git a/F3:F303/InterfaceBoard/hardware.c b/F3:F303/InterfaceBoard/hardware.c
index d3c8237..c3634a9 100644
--- a/F3:F303/InterfaceBoard/hardware.c
+++ b/F3:F303/InterfaceBoard/hardware.c
@@ -1,11 +1,36 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2026 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 "hardware.h"
 
+uint8_t Config_mode = 0;
+
 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);
+    // PA9 - config jumper (PU in), PA10 - USB pullup (PP)
+    GPIOA->MODER = MODER_I(9) | MODER_O(10) | MODER_AF(11) | MODER_AF(12) | MODER_AF(13) | MODER_AF(14);
+    GPIOA->OSPEEDR = OSPEED_HI(11) | OSPEED_HI(12) | OSPEED_HI(13) | OSPEED_HI(14);
+    GPIOA->PUPDR = PUPD_PU(9);
+    for(int i = 0; i < 10000; ++i) nop();
+    if(CFG_ON()) Config_mode = 1;
 }
 
 void hw_setup(){
diff --git a/F3:F303/InterfaceBoard/hardware.h b/F3:F303/InterfaceBoard/hardware.h
index 457c6fc..8dd6707 100644
--- a/F3:F303/InterfaceBoard/hardware.h
+++ b/F3:F303/InterfaceBoard/hardware.h
@@ -1,3 +1,21 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2026 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>
@@ -7,7 +25,12 @@
 #define USBPU_ON()  pin_clear(USBPU_port, USBPU_pin)
 #define USBPU_OFF() pin_set(USBPU_port, USBPU_pin)
 
+#define CFG_port    GPIOA
+#define CFG_pin     (1<<9)
+#define CFG_ON()    (CFG_port->IDR & CFG_pin)
+
 extern volatile uint32_t Tms;
+extern uint8_t Config_mode;
 
 void hw_setup();
 
diff --git a/F3:F303/InterfaceBoard/main.c b/F3:F303/InterfaceBoard/main.c
index af65cd3..5810040 100644
--- a/F3:F303/InterfaceBoard/main.c
+++ b/F3:F303/InterfaceBoard/main.c
@@ -43,15 +43,20 @@ int main(void){
     //uint32_t ctr = Tms;
     USBPU_ON();
     while(1){
-        /*if(Tms - ctr > 499){
-            ctr = Tms;
-        }*/
+        // Put here code working WITOUT USB connected
         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);
+        for(int i = 0; i < 6; ++i){ // just echo for first time
+            int l = USB_receive(i, (uint8_t*)inbuff, MAXSTRLEN);
+            if(l) USB_send(i, (uint8_t*)inbuff, l);
+        }
+        // and here is code what should run when USB connected
+        if(Config_mode){
+            int l = USB_receivestr(ICFG, inbuff, MAXSTRLEN);
+            if(l < 0) CFGWR("ERROR: USB buffer overflow or string was too long\n");
+            else if(l){
+                const char *ans = parse_cmd(inbuff);
+                if(ans) CFGWR(ans);
+            }
         }
     }
 }
diff --git a/F3:F303/InterfaceBoard/multiiface.bin b/F3:F303/InterfaceBoard/multiiface.bin
index aac465a..80ef1e4 100755
Binary files a/F3:F303/InterfaceBoard/multiiface.bin and b/F3:F303/InterfaceBoard/multiiface.bin differ
diff --git a/F3:F303/InterfaceBoard/multiiface.creator.user b/F3:F303/InterfaceBoard/multiiface.creator.user
index bd2b309..393c9cc 100644
--- a/F3:F303/InterfaceBoard/multiiface.creator.user
+++ b/F3:F303/InterfaceBoard/multiiface.creator.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 18.0.1, 2025-12-28T20:25:46. -->
+<!-- Written by QtCreator 18.0.2, 2026-02-11T23:33:00. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>
diff --git a/F3:F303/InterfaceBoard/proto.c b/F3:F303/InterfaceBoard/proto.c
index e2c6438..660eb49 100644
--- a/F3:F303/InterfaceBoard/proto.c
+++ b/F3:F303/InterfaceBoard/proto.c
@@ -1,3 +1,21 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2026 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 <string.h>
 
@@ -6,6 +24,8 @@
 #include "usb_dev.h"
 #include "version.inc"
 
+// all functions of this file could be run only in configuration mode
+
 static const char *const sOKn = "OK\n", *const sERRn = "ERR\n";
 
 //#define LOCBUFFSZ       (32)
@@ -25,19 +45,18 @@ const char *helpstring =
 ;
 
 static void dumpflash(){
-    USB_sendstr("userconf_sz="); USB_sendstr(u2str(the_conf.userconf_sz));
-    USB_sendstr("\ncurrentconfidx="); USB_sendstr(i2str(currentconfidx));
-    USB_putbyte('\n');
+    CFGWR("userconf_sz="); CFGWR(u2str(the_conf.userconf_sz));
+    CFGWR("\ncurrentconfidx="); CFGWRn(i2str(currentconfidx));
     for(int i = 0; i < InterfacesAmount; ++i){
-        USB_sendstr("interface"); USB_putbyte('0' + i);
-        USB_putbyte('=');
+        CFGWR("interface"); USB_putbyte(ICFG, '0' + i);
+        USB_putbyte(ICFG, '=');
         int l = the_conf.iIlengths[i] / 2;
         char *ptr = (char*) the_conf.iInterface[i];
         for(int j = 0; j < l; ++j){
-            USB_putbyte(*ptr);
+            USB_putbyte(ICFG, *ptr);
             ptr += 2;
         }
-        USB_putbyte('\n');
+        CFGn();
     }
 }
 
@@ -58,10 +77,10 @@ static void setiface(const char *str){
         *ptr++ = *nxt++;
         *ptr++ = 0;
     }
-    USB_sendstr(sOKn);
+    CFGWR(sOKn);
     return;
 err:
-    USB_sendstr(sERRn);
+    CFGWR(sERRn);
 }
 
 static const char* erpg(const char *str){
@@ -106,12 +125,11 @@ const char *parse_cmd(const char *buf){
             if(store_userconf()) return sERRn;
             return sOKn;
         case 'T':
-            USB_sendstr("T=");
-            USB_sendstr(u2str(Tms));
-            newline();
+            CFGWR("T=");
+            CFGWRn(u2str(Tms));
             break;
         default: // help
-            USB_sendstr(helpstring);
+            CFGWR(helpstring);
         break;
     }
     return NULL;
diff --git a/F3:F303/InterfaceBoard/proto.h b/F3:F303/InterfaceBoard/proto.h
index 5c6c029..7306aba 100644
--- a/F3:F303/InterfaceBoard/proto.h
+++ b/F3:F303/InterfaceBoard/proto.h
@@ -1,3 +1,21 @@
+/*
+ * This file is part of the multiiface project.
+ * Copyright 2026 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
 
 char *parse_cmd(char *buf);
diff --git a/F3:F303/InterfaceBoard/usb_descr.c b/F3:F303/InterfaceBoard/usb_descr.c
index 3e1a872..36ec5b8 100644
--- a/F3:F303/InterfaceBoard/usb_descr.c
+++ b/F3:F303/InterfaceBoard/usb_descr.c
@@ -15,6 +15,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <string.h> // memcpy
+#include "flash.h" // descriptors
+#include "hardware.h" // `config` flag
 #include "usb_descr.h"
 
 // low/high for uint16_t
@@ -55,7 +58,88 @@ static const uint8_t USB_DeviceQualifierDescriptor[] = {
     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)
+#define wTotalLength  (USB_DT_CONFIG_SIZE + (bTotNumEndpoints * 66))
+
+/*
+ *  _1stI - number of first interface
+ *  IDidx - 0 or index of string descriptor for given interface
+ *  EPx - number of virtual interrupt EP
+ *  EP - number of real EP in/out
+ */
+#define USB_IAD(_1stI, IDidx, EPx, EP)  \
+    USB_DT_IAD_SIZE, /* bLength: IAD size */ \
+    USB_DT_IAD, /* bDescriptorType: IAD */ \
+    _1stI, /* bFirstInterface */ \
+    2, /* bInterfaceCount */ \
+    2, /* bFunctionClass: CDC */ \
+    2, /* bFunctionSubClass */ \
+    0, /* bFunctionProtocol */ \
+    0, /* iFunction */ \
+    /* Interface Descriptor */ \
+    USB_DT_INTERFACE_SIZE, /* bLength: Interface Descriptor size */ \
+    USB_DT_INTERFACE, /* bDescriptorType: Interface */ \
+    _1stI, /* bInterfaceNumber: Number of Interface */ \
+    0, /* bAlternateSetting: Alternate setting */ \
+    1, /* bNumEndpoints: one for this */ \
+    USB_CLASS_COMM, /* bInterfaceClass */ \
+    2, /* bInterfaceSubClass: ACM */ \
+    0, /* bInterfaceProtocol */ \
+    IDidx, /* iInterface */ \
+    /* CDC descriptor */ \
+    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 */ \
+    (_1stI+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 */ \
+    _1stI, /* bMasterInterface: Communication class interface */ \
+    (_1stI+1), /* bSlaveInterface0: Data Class Interface */ \
+    /* Virtual endpoint 1 Descriptor */ \
+    USB_DT_ENDPOINT_SIZE, /* bLength: Endpoint Descriptor size */ \
+    USB_DT_ENDPOINT, /* bDescriptorType: Endpoint */ \
+    (0x80+EPx), /* bEndpointAddress IN8 - non-existant */ \
+    USB_BM_ATTR_INTERRUPT, /* bmAttributes: Interrupt */ \
+    L16(USB_EP1BUFSZ), /* wMaxPacketSize LO */ \
+    H16(USB_EP1BUFSZ), /* wMaxPacketSize HI */ \
+    0x10, /* bInterval: 16ms */ \
+    /* DATA endpoint */ \
+    USB_DT_INTERFACE_SIZE, /* bLength: Interface Descriptor size */ \
+    USB_DT_INTERFACE, /* bDescriptorType: Interface */ \
+    (_1stI+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 */ \
+    (0x80+EP), /* 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 */ \
+    EP, /* bEndpointAddress: OUT1 */ \
+    USB_BM_ATTR_BULK, /* bmAttributes: Bulk */ \
+    L16(USB_RXBUFSZ), /* wMaxPacketSize LO */ \
+    H16(USB_RXBUFSZ), /* wMaxPacketSize HI */ \
+    0 /* bInterval: ignore for Bulk transfer */
+
 
 static const uint8_t USB_ConfigDescriptor[] = {
     // Configuration Descriptor
@@ -68,89 +152,52 @@ static const uint8_t USB_ConfigDescriptor[] = {
     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
-
+    //--IADs-------------------------------------------------------------------------
+    USB_IAD(0,  iINTERFACE_DESCR1, 8,  1),
+    USB_IAD(2,  iINTERFACE_DESCR2, 9,  2),
+    USB_IAD(4,  iINTERFACE_DESCR3, 10, 3),
+    USB_IAD(6,  iINTERFACE_DESCR4, 11, 4),
+    USB_IAD(8,  iINTERFACE_DESCR5, 12, 5),
+    USB_IAD(10, iINTERFACE_DESCR6, 13, 6),
+    USB_IAD(12, iINTERFACE_DESCR7, 14, 7),
 };
 
-//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");
+
+// iInterface will change on initialisation by config
+#define _USB_IIDESCR_(str) {sizeof(str), 0x03, str}
+typedef struct{
+    uint8_t  bLength;
+    uint8_t  bDescriptorType;
+    uint16_t bString[MAX_IINTERFACE_SZ];
+}iidescr_t;
+static iidescr_t iids[InterfacesAmount] = {
+    _USB_IIDESCR_(u"iface0"),
+    _USB_IIDESCR_(u"iface1"),
+    _USB_IIDESCR_(u"iface2"),
+    _USB_IIDESCR_(u"iface3"),
+    _USB_IIDESCR_(u"iface4"),
+    _USB_IIDESCR_(u"iface5"),
+    _USB_IIDESCR_(u"iface6"),
+};
+
 
 static const void* const StringDescriptor[iDESCR_AMOUNT] = {
     [iLANGUAGE_DESCR] = &LD,
     [iMANUFACTURER_DESCR] = &MD,
     [iPRODUCT_DESCR] = &PD,
     [iSERIAL_DESCR] = &SD,
-    [iINTERFACE_DESCR1] = &ID
+    [iINTERFACE_DESCR1] = &iids[0],
+    [iINTERFACE_DESCR2] = &iids[1],
+    [iINTERFACE_DESCR3] = &iids[2],
+    [iINTERFACE_DESCR4] = &iids[3],
+    [iINTERFACE_DESCR5] = &iids[4],
+    [iINTERFACE_DESCR6] = &iids[5],
+    [iINTERFACE_DESCR7] = &iids[6],
 };
 
 static void wr0(const uint8_t *buf, uint16_t size, uint16_t askedsize){
@@ -208,3 +255,18 @@ void get_descriptor(config_pack_t *pack){
             break;
     }
 }
+// change values of iInterface by content of global config
+void setup_interfaces(){
+    for(int i = 0; i < InterfacesAmount; ++i){
+        if(the_conf.iIlengths[i]){
+            iids[i].bLength = the_conf.iIlengths[i] + 2; // +2 - for bLength and bDescriptorType
+            memcpy(iids[i].bString, the_conf.iInterface[i], the_conf.iIlengths[i]);
+        }
+        iids[i].bDescriptorType = 0x03;
+    }
+    if(Config_mode){
+        // configuration interface identificator is hardware fixed
+        memcpy(iids[ICFG].bString, u"multiportCFG", 24);
+        iids[ICFG].bLength = 48;
+    }
+}
diff --git a/F3:F303/InterfaceBoard/usb_descr.h b/F3:F303/InterfaceBoard/usb_descr.h
index 39eeb76..2390859 100644
--- a/F3:F303/InterfaceBoard/usb_descr.h
+++ b/F3:F303/InterfaceBoard/usb_descr.h
@@ -31,21 +31,24 @@
 #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
+// index of interface (ep number minus one)
 #define ISerial0            0
-#define ICFG                0
 #define ISerial1            1
 #define ISerial2            2
 #define ISerial3            3
 #define ISerial4            4
-#define ISPI                5
-#define ICAN                6
+#define ICAN                5
+#define ISPI                6
+#define ICFG                6
+// EP number of interface
+#define EPNO(i) (i + 1)
+
+// amount of interfaces (including virtual) except 0
+#define bNumInterfaces      (2*InterfacesAmount)
+// amount of endpoints used
+#define bTotNumEndpoints    (1+InterfacesAmount)
 
 // powered
 #define BusPowered          (1<<7)
@@ -55,10 +58,14 @@
 // buffer sizes
 // for USB FS EP0 buffers are from 8 to 64 bytes long
 #define USB_EP0BUFSZ    64
+// virtual
 #define USB_EP1BUFSZ    10
-// Rx/Tx EPs
-#define USB_RXBUFSZ     64
-#define USB_TXBUFSZ     64
+// Rx/Tx EPs (USB_BTABLE_SIZE-64-2*USB_EP0BUFSZ)/(2*InterfacesAmount) rounded to 8
+// 534 / 112 -> 4
+#define _RTBUFSZ8       (((USB_BTABLE_SIZE) - 64 - (2 * (USB_EP0BUFSZ)))/(16 * (InterfacesAmount)))
+// 32 bytes; so we have free 86 bytes which can't be used
+#define USB_RXBUFSZ     (8 * (_RTBUFSZ8))
+#define USB_TXBUFSZ     (8 * (_RTBUFSZ8))
 
 // string descriptors
 enum{
@@ -67,7 +74,14 @@ enum{
     iPRODUCT_DESCR,
     iSERIAL_DESCR,
     iINTERFACE_DESCR1,
+    iINTERFACE_DESCR2,
+    iINTERFACE_DESCR3,
+    iINTERFACE_DESCR4,
+    iINTERFACE_DESCR5,
+    iINTERFACE_DESCR6,
+    iINTERFACE_DESCR7,
     iDESCR_AMOUNT
 };
 
 void get_descriptor(config_pack_t *pack);
+void setup_interfaces();
diff --git a/F3:F303/InterfaceBoard/usb_dev.c b/F3:F303/InterfaceBoard/usb_dev.c
index 8d61eee..81fa994 100644
--- a/F3:F303/InterfaceBoard/usb_dev.c
+++ b/F3:F303/InterfaceBoard/usb_dev.c
@@ -17,6 +17,7 @@
 
 #include <string.h>
 
+#include "hardware.h"
 #include "ringbuffer.h"
 #include "usb_descr.h"
 #include "usb_dev.h"
@@ -37,170 +38,226 @@
 #define CONTROL_RTS                     0x02
 
 // inbuf overflow when receiving
-static volatile uint8_t bufovrfl = 0;
+static volatile uint8_t bufovrfl[InterfacesAmount] = {0};
 
 // receive buffer: hold data until chkin() call
-static uint8_t volatile rcvbuf[USB_RXBUFSZ];
-static uint8_t volatile rcvbuflen = 0;
+static uint8_t volatile rcvbuf[InterfacesAmount][USB_RXBUFSZ];
+static uint8_t volatile rcvbuflen[InterfacesAmount] = {0};
 // line coding
-usb_LineCoding WEAK lineCoding = {115200, 0, 0, 8};
+#define DEFL    {115200, 0, 0, 8}
+usb_LineCoding lineCoding[InterfacesAmount] = {DEFL,DEFL,DEFL,DEFL,DEFL,DEFL,DEFL};
 // CDC configured and ready to use
-volatile uint8_t CDCready = 0;
+volatile uint8_t CDCready[InterfacesAmount] = {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 uint8_t obuf[InterfacesAmount][RBOUTSZ], ibuf[InterfacesAmount][RBINSZ];
+#define OBUF(N)  {.data = obuf[N], .length = RBOUTSZ, .head = 0, .tail = 0}
+static volatile ringbuffer rbout[InterfacesAmount] = {OBUF(0), OBUF(1), OBUF(2), OBUF(3), OBUF(4), OBUF(5), OBUF(6)};
+#define IBUF(N)  {.data = ibuf[N], .length = RBINSZ, .head = 0, .tail = 0}
+static volatile ringbuffer rbin[InterfacesAmount] = {IBUF(0), IBUF(1), IBUF(2), IBUF(3), IBUF(4), IBUF(5), IBUF(6)};
+// last send data size (<0 if USB transfer ready)
+static volatile int lastdsz[InterfacesAmount] = {-1, -1, -1, -1, -1, -1, -1};
 
-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);
+static void chkin(uint8_t ifno){
+    if(bufovrfl[ifno]) return; // allow user to know that previous buffer was overflowed and cleared
+    if(!rcvbuflen[ifno]) return;
+    int w = RB_write((ringbuffer*)&rbin[ifno], (uint8_t*)rcvbuf[ifno], rcvbuflen[ifno]);
     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
+    if(w != rcvbuflen[ifno]) bufovrfl[ifno] = 1;
+    rcvbuflen[ifno] = 0;
+    uint16_t status = KEEP_DTOG(USB->EPnR[1+ifno]); // don't change DTOG
+    USB->EPnR[1+ifno] = (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(){
+static void send_next(uint8_t ifno){
     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;
+    int buflen = RB_read((ringbuffer*)&rbout[ifno], (uint8_t*)usbbuff, USB_TXBUFSZ);
+    if(!CDCready[ifno]){
+        lastdsz[ifno] = -1;
         return;
     }
-    EP_Write(1, (uint8_t*)usbbuff, buflen);
-    lastdsz = buflen;
+    if(buflen == 0){
+        if(lastdsz[ifno] == USB_TXBUFSZ){
+            EP_Write(1+ifno, NULL, 0); // send ZLP after 64 bits packet when nothing more to send
+            lastdsz[ifno] = 0;
+        }else lastdsz[ifno] = -1; // OK. User can start sending data
+        return;
+    }else if(buflen < 0){
+        lastdsz[ifno] = -1;
+        return;
+    }
+    EP_Write(1+ifno, (uint8_t*)usbbuff, buflen);
+    lastdsz[ifno] = buflen;
 }
 
 // data IN/OUT handler
 static void rxtx_handler(){
-    uint16_t epstatus = KEEP_DTOG(USB->EPnR[1]);
+    uint8_t ifno = (USB->ISTR & USB_ISTR_EPID) - 1;
+    if(ifno > InterfacesAmount-1){
+        return;
+    }
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[1+ifno]);
     if(RX_FLAG(epstatus)){ // receive data
-        if(rcvbuflen){
-            bufovrfl = 1; // lost last data
-            rcvbuflen = 0;
+        if(rcvbuflen[ifno]){
+            bufovrfl[ifno] = 1; // lost last data
+            rcvbuflen[ifno] = 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
+        rcvbuflen[ifno] = EP_Read(1+ifno, (uint8_t*)rcvbuf[ifno]);
+        USB->EPnR[1+ifno] = epstatus & ~(USB_EPnR_CTR_RX | USB_EPnR_STAT_RX | USB_EPnR_STAT_TX); // keep RX in STALL state until read data
+        chkin(ifno); // 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();
+        USB->EPnR[1+ifno] = (epstatus & ~(USB_EPnR_CTR_TX | USB_EPnR_STAT_TX)) ^ USB_EPnR_STAT_RX;
+        send_next(ifno);
     }
 }
 
-// weak handlers: change them somewhere else if you want to setup USART
 // SET_LINE_CODING
-void WEAK linecoding_handler(usb_LineCoding *lc){
-    lineCoding = *lc;
+void linecoding_handler(uint8_t ifno, usb_LineCoding *lc){
+    lineCoding[ifno] = *lc;
+    // TODO: set up interfaces
+}
+
+// clear IN/OUT buffers on connection
+static void clearbufs(uint8_t ifno){
+    uint32_t T0 = Tms;
+    while(Tms - T0 < 10){ // wait no more than 10ms
+        if(1 == RB_clearbuf((ringbuffer*)&rbin[ifno])) break;
+    }
+    T0 = Tms;
+    while(Tms - T0 < 10){
+        if(1 == RB_clearbuf((ringbuffer*)&rbout[ifno])) break;
+    }
 }
 
 // SET_CONTROL_LINE_STATE
-void WEAK clstate_handler(uint16_t val){
-    CDCready = val; // CONTROL_DTR | CONTROL_RTS -> interface connected; 0 -> disconnected
+void clstate_handler(uint8_t ifno, uint16_t val){
+    CDCready[ifno] = val; // CONTROL_DTR | CONTROL_RTS -> interface connected; 0 -> disconnected
+    lastdsz[ifno] = -1;
+    if(val) clearbufs(ifno);
 }
 
-// SEND_BREAK
-void WEAK break_handler(){
-    CDCready = 0;
+// SEND_BREAK - disconnect interface and clear its buffers
+// this is a fake handler as classic CDC ACM never receives this
+void break_handler(uint8_t ifno){
+    CDCready[ifno] = 0;
 }
 
-
 // USB is configured: setup endpoints
 void set_configuration(){
-    EP_Init(1, EP_TYPE_BULK, USB_TXBUFSZ, USB_RXBUFSZ, rxtx_handler); // IN1 and OUT1
+    for(int i = 0; i < InterfacesAmount; ++i){
+        IWDG->KR = IWDG_REFRESH;
+        int r = EP_Init(1+i, EP_TYPE_BULK, USB_TXBUFSZ, USB_RXBUFSZ, rxtx_handler);
+        if(r){
+            // OOPS, can't init EP. What to do? Cry?
+            break;
+        }
+    }
 }
 
-// PL2303 CLASS request
+// USB CDC 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;
+    uint8_t ifno = req->wIndex >> 1;
+    if(ifno > InterfacesAmount-1){ // wrong interface number
+        EP_WriteIRQ(0, NULL, 0);
+        return;
+    }
     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;
+    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(ifno, (usb_LineCoding*)data);
+            break;
+        case GET_LINE_CODING:
+            EP_WriteIRQ(0, (uint8_t*)&lineCoding[ifno], sizeof(lineCoding));
+            break;
+        case SET_CONTROL_LINE_STATE:
+            clstate_handler(ifno, req->wValue);
+            break;
+        case SEND_BREAK:
+            break_handler(ifno);
+            break;
         default:
-            if(dev2host) EP_WriteIRQ(0, NULL, 0);
+            // WTF?
+            break;
+        }
+        break;
+    default:
+        // WTF?
+        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;
+int USB_sendall(uint8_t ifno){
+    uint32_t T0 = Tms;
+    while(lastdsz[ifno] > 0){
+        if(Tms - T0 > DISCONN_TMOUT){
+            break_handler(ifno);
+            return FALSE;
+        }
+        if(!CDCready[ifno]) return FALSE;
+        IWDG->KR = IWDG_REFRESH;
     }
     return TRUE;
 }
 
 // put `buf` into queue to send
-int USB_send(const uint8_t *buf, int len){
-    if(!buf || !CDCready || !len) return FALSE;
+int USB_send(uint8_t ifno, const uint8_t *buf, int len){
+    if(!buf || !CDCready[ifno] || !len) return FALSE;
+    uint32_t T0 = Tms;
     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(Tms - T0 > DISCONN_TMOUT){
+            break_handler(ifno);
+            return FALSE;
         }
-        if(portion > len) portion = len;
-        int a = RB_write((ringbuffer*)&rbout, buf, portion);
+        if(!CDCready[ifno]) return FALSE;
+        IWDG->KR = IWDG_REFRESH;
+        int a = RB_write((ringbuffer*)&rbout[ifno], buf, len);
         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
+        }else if(a == 0){ // overfull
+            if(lastdsz[ifno] < 0) send_next(ifno);
+        }
     }
+    if(buf[len-1] == '\n' && lastdsz[ifno] < 0) send_next(ifno);
     return TRUE;
 }
 
-int USB_putbyte(uint8_t byte){
-    if(!CDCready) return FALSE;
+int USB_putbyte(uint8_t ifno, uint8_t byte){
+    if(!CDCready[ifno]) return FALSE;
     int l = 0;
-    while((l = RB_write((ringbuffer*)&rbout, &byte, 1)) != 1){
-        if(l < 0) continue;
+    uint32_t T0 = Tms;
+    while((l = RB_write((ringbuffer*)&rbout[ifno], &byte, 1)) != 1){
+        if(Tms - T0 > DISCONN_TMOUT){
+            break_handler(ifno);
+            return FALSE;
+        }
+        if(!CDCready[ifno]) return FALSE;
+        IWDG->KR = IWDG_REFRESH;
+        if(l == 0){ // overfull
+            if(lastdsz[ifno] < 0) send_next(ifno);
+            continue;
+        }
     }
-    if(lastdsz == 0) send_next(); // need to run manually - all data sent, so no IRQ on IN
+    // send line if got EOL
+    if(byte == '\n' && lastdsz[ifno] < 0) send_next(ifno);
     return TRUE;
 }
 
-int USB_sendstr(const char *string){
-    if(!string || !CDCready) return FALSE;
-    int len = 0;
-    const char *b = string;
-    while(*b++) ++len;
+int USB_sendstr(uint8_t ifno, const char *string){
+    if(!string || !CDCready[ifno]) return FALSE;
+    int len = strlen(string);
     if(!len) return FALSE;
-    return USB_send((const uint8_t*)string, len);
+    return USB_send(ifno, (const uint8_t*)string, len);
 }
 
 /**
@@ -209,14 +266,14 @@ int USB_sendstr(const char *string){
  * @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;
+int USB_receive(uint8_t ifno, uint8_t *buf, int len){
+    chkin(ifno); // rxtx_handler could leave last message unwritten if buffer was busy
+    if(bufovrfl[ifno]){
+        while(1 != RB_clearbuf((ringbuffer*)&rbin[ifno])); // run watchdog in case of problems
+        bufovrfl[ifno] = 0;
         return -1;
     }
-    int sz = RB_read((ringbuffer*)&rbin, buf, len);
+    int sz = RB_read((ringbuffer*)&rbin[ifno], buf, len);
     if(sz < 0) return 0; // buffer in writting state
     return sz;
 }
@@ -227,17 +284,17 @@ int USB_receive(uint8_t *buf, int len){
  * @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;
+int USB_receivestr(uint8_t ifno, char *buf, int len){
+    chkin(ifno); // rxtx_handler could leave last message unwritten if buffer was busy
+    if(bufovrfl[ifno]){
+        while(1 != RB_clearbuf((ringbuffer*)&rbin[ifno]));
+        bufovrfl[ifno] = 0;
         return -1;
     }
-    int l = RB_readto((ringbuffer*)&rbin, '\n', (uint8_t*)buf, len);
+    int l = RB_readto((ringbuffer*)&rbin[ifno], '\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));
+        if(rbin[ifno].length == RB_datalen((ringbuffer*)&rbin[ifno])){ // buffer is full but no '\n' found
+            while(1 != RB_clearbuf((ringbuffer*)&rbin[ifno]));
             return -1;
         }
         return 0;
@@ -246,4 +303,3 @@ int USB_receivestr(char *buf, int len){
     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
index 1f8003c..07b1efb 100644
--- a/F3:F303/InterfaceBoard/usb_dev.h
+++ b/F3:F303/InterfaceBoard/usb_dev.h
@@ -18,6 +18,7 @@
 
 #include <stm32f3.h>
 #include "usb_lib.h"
+#include "usb_descr.h"
 
 typedef struct {
     uint32_t dwDTERate;
@@ -34,24 +35,29 @@ typedef struct {
     uint8_t bDataBits;
 } __attribute__ ((packed)) usb_LineCoding;
 
-extern usb_LineCoding lineCoding;
-extern volatile uint8_t CDCready;
+extern volatile uint8_t CDCready[InterfacesAmount];
 
-void break_handler();
-void clstate_handler(uint16_t val);
-void linecoding_handler(usb_LineCoding *lc);
+void break_handler(uint8_t ifno);
+void clstate_handler(uint8_t ifno, uint16_t val);
+void linecoding_handler(uint8_t ifno, usb_LineCoding *lc);
 
+// as ugly CDC have no BREAK after disconnected client in non-canonical mode, we should use timeout - more than 2ms
+#define DISCONN_TMOUT   (2)
 
 // sizes of ringbuffers for outgoing and incoming data
-#define RBOUTSZ     (1024)
-#define RBINSZ      (1024)
+#define RBOUTSZ     (256)
+#define RBINSZ      (256)
 
-#define newline()   USB_putbyte('\n')
-#define USND(s)     do{USB_sendstr(s); USB_putbyte('\n');}while(0)
+#define newline(ifno)   USB_putbyte(ifno, '\n')
+#define USND(ifno, s)   do{USB_sendstr(ifno, s); USB_putbyte(ifno, '\n');}while(0)
+// configuratin interface macros
+#define CFGWR(s)        USB_sendstr(ICFG, s)
+#define CFGWRn(s)       do{USB_sendstr(ICFG, s); USB_putbyte(ICFG, '\n');}while(0)
+#define CFGn()          USB_putbyte(ICFG, '\n')
 
-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);
+int USB_sendall(uint8_t ifno);
+int USB_send(uint8_t ifno, const uint8_t *buf, int len);
+int USB_putbyte(uint8_t ifno, uint8_t byte);
+int USB_sendstr(uint8_t ifno, const char *string);
+int USB_receive(uint8_t ifno, uint8_t *buf, int len);
+int USB_receivestr(uint8_t ifno, char *buf, int len);
diff --git a/F3:F303/InterfaceBoard/usb_lib.c b/F3:F303/InterfaceBoard/usb_lib.c
index 9f01a8f..f5dbd5f 100644
--- a/F3:F303/InterfaceBoard/usb_lib.c
+++ b/F3:F303/InterfaceBoard/usb_lib.c
@@ -356,6 +356,7 @@ void USB_setup(){
     USB->BCDR |= USB_BCDR_DPPU;
     NVIC_EnableIRQ(USB_IRQn);
 #endif
+    setup_interfaces(); // refresh interfaces names
 }
 
 
diff --git a/F3:F303/InterfaceBoard/version.inc b/F3:F303/InterfaceBoard/version.inc
index d737cd6..c0afe52 100644
--- a/F3:F303/InterfaceBoard/version.inc
+++ b/F3:F303/InterfaceBoard/version.inc
@@ -1,2 +1,2 @@
-#define BUILD_NUMBER "8"
-#define BUILD_DATE "2025-12-28"
+#define BUILD_NUMBER "20"
+#define BUILD_DATE "2026-02-11"