diff --git a/F3:F303/Seven_CDCs/7CDCs.files b/F3:F303/Seven_CDCs/7CDCs.files
index a912955..45f8ac8 100644
--- a/F3:F303/Seven_CDCs/7CDCs.files
+++ b/F3:F303/Seven_CDCs/7CDCs.files
@@ -1,3 +1,7 @@
+can.c
+can.h
+canproto.c
+canproto.h
 cmdproto.c
 cmdproto.h
 debug.h
diff --git a/F3:F303/Seven_CDCs/can.c b/F3:F303/Seven_CDCs/can.c
new file mode 100644
index 0000000..4db334f
--- /dev/null
+++ b/F3:F303/Seven_CDCs/can.c
@@ -0,0 +1,383 @@
+/*
+ * This file is part of the 7CDCs project.
+ * 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 "can.h"
+#include "hardware.h"
+#include "strfunc.h"
+#include "usb.h"
+
+#define SEND(str)       do{USB_sendstr(CAN_IDX, str);}while(0)
+#define SENDN(str)      do{USB_sendstr(CAN_IDX, str); USB_putbyte(CAN_IDX, '\n');}while(0)
+
+// PB8/PB9!!!
+
+#include <string.h> // memcpy
+
+// circular buffer for  received messages
+static CAN_message messages[CAN_INMESSAGE_SIZE];
+static uint8_t first_free_idx = 0;    // index of first empty cell
+static int8_t first_nonfree_idx = -1; // index of first data cell
+static uint16_t oldspeed = 100; // speed of last init
+uint32_t floodT = FLOOD_PERIOD_MS; // flood period in ms
+static uint8_t incrflood = 0; // ==1 for incremental flooding
+
+static uint32_t last_err_code = 0;
+static CAN_status can_status = CAN_STOP;
+
+static void can_process_fifo(uint8_t fifo_num);
+
+static CAN_message loc_flood_msg;
+static CAN_message *flood_msg = NULL; // == loc_flood_msg - to flood
+
+CAN_status CAN_get_status(){
+    int st = can_status;
+    can_status = CAN_OK;
+    return st;
+}
+
+// push next message into buffer; return 1 if buffer overfull
+static int CAN_messagebuf_push(CAN_message *msg){
+    //MSG("Try to push\n");
+#ifdef EBUG
+        SENDN("push");
+#endif
+    if(first_free_idx == first_nonfree_idx){
+#ifdef EBUG
+        SENDN("INBUF OVERFULL");
+#endif
+        return 1; // no free space
+    }
+    if(first_nonfree_idx < 0) first_nonfree_idx = 0;  // first message in empty buffer
+    memcpy(&messages[first_free_idx++], msg, sizeof(CAN_message));
+    // need to roll?
+    if(first_free_idx == CAN_INMESSAGE_SIZE) first_free_idx = 0;
+    return 0;
+}
+
+// pop message from buffer
+CAN_message *CAN_messagebuf_pop(){
+    if(first_nonfree_idx < 0) return NULL;
+    CAN_message *msg = &messages[first_nonfree_idx++];
+    if(first_nonfree_idx == CAN_INMESSAGE_SIZE) first_nonfree_idx = 0;
+    if(first_nonfree_idx == first_free_idx){ // buffer is empty - refresh it
+        first_nonfree_idx = -1;
+        first_free_idx = 0;
+    }
+    return msg;
+}
+
+void CAN_reinit(uint16_t speed){
+    CAN->TSR |= CAN_TSR_ABRQ0 | CAN_TSR_ABRQ1 | CAN_TSR_ABRQ2;
+    RCC->APB1RSTR |= RCC_APB1RSTR_CANRST;
+    RCC->APB1RSTR &= ~RCC_APB1RSTR_CANRST;
+    CAN_setup(speed);
+}
+
+/*
+Can filtering: FSCx=0 (CAN->FS1R) -> 16-bit identifiers
+MASK: FBMx=0 (CAN->FM1R), two filters (n in FR1 and n+1 in FR2)
+    ID:   CAN->sFilterRegister[x].FRn[0..15]
+    MASK: CAN->sFilterRegister[x].FRn[16..31]
+    FR bits:  STID[10:0] RTR IDE EXID[17:15]
+LIST: FBMx=1, four filters (n&n+1 in FR1, n+2&n+3 in FR2)
+    IDn:   CAN->sFilterRegister[x].FRn[0..15]
+    IDn+1: CAN->sFilterRegister[x].FRn[16..31]
+*/
+
+/*
+Can timing: main freq - APB (PLL=48MHz)
+segment = 1sync + TBS1 + TBS2, sample point is between TBS1 and TBS2,
+so if TBS1=4 and TBS2=3, sum=8, bit sampling freq is 48/8 = 6MHz
+-> to get   100kbps we need prescaler=60
+            250kbps - 24
+            500kbps - 12
+            1MBps   - 6
+*/
+
+// speed - in kbps
+void CAN_setup(uint16_t speed){
+    //LED_off(LED1);
+    if(speed == 0) speed = oldspeed;
+    else if(speed < 50) speed = 50;
+    else if(speed > 3000) speed = 3000;
+    oldspeed = speed;
+    uint32_t tmout = 16000000;
+    // Configure GPIO: PB8 - CAN_Rx, PB9 - CAN_Tx (both AF9)
+    RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
+    GPIOB->MODER = (GPIOB->MODER & ~(GPIO_MODER_MODER8 | GPIO_MODER_MODER9))
+                 | (GPIO_MODER_MODER8_AF | GPIO_MODER_MODER9_AF);
+    GPIOB->AFR[1] = (GPIOB->AFR[1] &~ (GPIO_AFRH_AFRH0 | GPIO_AFRH_AFRH1))
+                  | AFRf(9, 8) | AFRf(9, 9);
+    /* Enable the peripheral clock CAN */
+    RCC->APB1ENR |= RCC_APB1ENR_CANEN;
+    /* Configure CAN */
+    /* (1) Enter CAN init mode to write the configuration */
+    /* (2) Wait the init mode entering */
+    /* (3) Exit sleep mode */
+    /* (4) Normal mode, set timing to 100kb/s: TBS1 = 4, TBS2 = 3, prescaler = 60 */
+    /* (5) Leave init mode */
+    /* (6) Wait the init mode leaving */
+    /* (7) Enter filter init mode, (16-bit + mask, bank 0 for FIFO 0) */
+    /* (8) Acivate filter 0 for two IDs */
+    /* (9) Identifier list mode */
+    /* (10) Set the Id list */
+    /* (12) Leave filter init */
+    /* (13) Set error interrupts enable (& bus off) */
+    CAN->MCR |= CAN_MCR_INRQ; /* (1) */
+    while((CAN->MSR & CAN_MSR_INAK) != CAN_MSR_INAK) /* (2) */
+        if(--tmout == 0) break;
+    CAN->MCR &=~ CAN_MCR_SLEEP; /* (3) */
+    CAN->MCR |= CAN_MCR_ABOM; /* allow automatically bus-off */
+
+    CAN->BTR =  2 << 20 | 3 << 16 | (4500/speed - 1); //| CAN_BTR_SILM | CAN_BTR_LBKM; /* (4) */
+    CAN->MCR &= ~CAN_MCR_INRQ; /* (5) */
+    tmout = 16000000;
+    while((CAN->MSR & CAN_MSR_INAK) == CAN_MSR_INAK) /* (6) */
+        if(--tmout == 0) break;
+    // accept ALL
+    CAN->FMR = CAN_FMR_FINIT; /* (7) */
+    CAN->FA1R = CAN_FA1R_FACT0 | CAN_FA1R_FACT1; /* (8) */
+    // set to 1 all needed bits of CAN->FFA1R to switch given filters to FIFO1
+    CAN->sFilterRegister[0].FR1 = (1<<21)|(1<<5); // all odd IDs
+    CAN->FFA1R = 2; // filter 1 for FIFO1, filter 0 - for FIFO0
+    CAN->sFilterRegister[1].FR1 = (1<<21); // all even IDs
+    CAN->FMR &= ~CAN_FMR_FINIT; /* (12) */
+    CAN->IER |= CAN_IER_ERRIE | CAN_IER_FOVIE0 | CAN_IER_FOVIE1 | CAN_IER_BOFIE; /* (13) */
+
+    /* Configure IT */
+    NVIC_SetPriority(USB_LP_CAN_RX0_IRQn, 0); // RX FIFO0 IRQ
+    NVIC_SetPriority(CAN_RX1_IRQn, 0); // RX FIFO1 IRQ
+    NVIC_SetPriority(CAN_SCE_IRQn, 0); // RX status changed IRQ
+    NVIC_EnableIRQ(USB_LP_CAN_RX0_IRQn);
+    NVIC_EnableIRQ(CAN_RX1_IRQn);
+    NVIC_EnableIRQ(CAN_SCE_IRQn);
+    CAN->MSR = 0; // clear SLAKI, WKUI, ERRI
+    can_status = CAN_READY;
+}
+
+void printCANerr(){
+    if(!last_err_code) last_err_code = CAN->ESR;
+    if(!last_err_code){
+        SENDN("No errors");
+        return;
+    }
+    SEND("Receive error counter: ");
+    SEND(u2str((last_err_code & CAN_ESR_REC)>>24));
+    SEND("\nTransmit error counter: ");
+    SEND(u2str((last_err_code & CAN_ESR_TEC)>>16));
+    SEND("\nLast error code: ");
+    int lec = (last_err_code & CAN_ESR_LEC) >> 4;
+    const char *errmsg = "No";
+    switch(lec){
+        case 1: errmsg = "Stuff"; break;
+        case 2: errmsg = "Form"; break;
+        case 3: errmsg = "Ack"; break;
+        case 4: errmsg = "Bit recessive"; break;
+        case 5: errmsg = "Bit dominant"; break;
+        case 6: errmsg = "CRC"; break;
+        case 7: errmsg = "(set by software)"; break;
+    }
+    SEND(errmsg); SENDN(" error");
+    if(last_err_code & CAN_ESR_BOFF) SENDN("Bus off");
+    if(last_err_code & CAN_ESR_EPVF) SENDN("Passive error limit");
+    if(last_err_code & CAN_ESR_EWGF) SENDN("Error counter limit");
+    last_err_code = 0;
+}
+
+void can_proc(){
+#ifdef EBUG
+    if(last_err_code){
+        SEND("Error, ESR=");
+        SENDN(u2str(last_err_code));
+        last_err_code = 0;
+    }
+#endif
+    // check for messages in FIFO0 & FIFO1
+    if(CAN->RF0R & CAN_RF0R_FMP0){
+        can_process_fifo(0);
+    }
+    if(CAN->RF1R & CAN_RF1R_FMP1){
+        can_process_fifo(1);
+    }
+    IWDG->KR = IWDG_REFRESH;
+    if(CAN->ESR & (CAN_ESR_BOFF | CAN_ESR_EPVF | CAN_ESR_EWGF)){ // much errors - restart CAN BUS
+        SENDN("\nToo much errors, restarting CAN!");
+        printCANerr();
+        // request abort for all mailboxes
+        CAN->TSR |= CAN_TSR_ABRQ0 | CAN_TSR_ABRQ1 | CAN_TSR_ABRQ2;
+        // reset CAN bus
+        RCC->APB1RSTR |= RCC_APB1RSTR_CANRST;
+        RCC->APB1RSTR &= ~RCC_APB1RSTR_CANRST;
+        CAN_setup(0);
+    }
+    static uint32_t lastFloodTime = 0;
+    static uint32_t incrmessagectr = 0;
+    if(flood_msg && (Tms - lastFloodTime) >= floodT){ // flood every ~5ms
+        lastFloodTime = Tms;
+        can_send(flood_msg->data, flood_msg->length, flood_msg->ID);
+    }else if(incrflood && (Tms - lastFloodTime) >= floodT){
+        lastFloodTime = Tms;
+        if(CAN_OK == can_send((uint8_t*)&incrmessagectr, 4, flood_msg->ID)) ++incrmessagectr;
+    }
+}
+
+CAN_status can_send(uint8_t *msg, uint8_t len, uint16_t target_id){
+    uint8_t mailbox = 0;
+    // check first free mailbox
+    if(CAN->TSR & (CAN_TSR_TME)){
+        mailbox = (CAN->TSR & CAN_TSR_CODE) >> 24;
+    }else{ // no free mailboxes
+#ifdef EBUG
+        SENDN("No free mailboxes");
+#endif
+        return CAN_BUSY;
+    }
+#ifdef EBUG
+    SEND("Send data. Len="); SENDN(u2str(len));
+    SEND(", tagid="); SENDN(u2str(target_id));
+    SEND(", data=");
+    for(int i = 0; i < len; ++i){
+        SEND(" "); SEND(uhex2str(msg[i]));
+    }
+    SEND("\n");
+#endif
+    CAN_TxMailBox_TypeDef *box = &CAN->sTxMailBox[mailbox];
+    uint32_t lb = 0, hb = 0;
+    switch(len){
+        case 8:
+            hb |= (uint32_t)msg[7] << 24;
+            __attribute__((fallthrough));
+        case 7:
+            hb |= (uint32_t)msg[6] << 16;
+            __attribute__((fallthrough));
+        case 6:
+            hb |= (uint32_t)msg[5] << 8;
+            __attribute__((fallthrough));
+        case 5:
+            hb |= (uint32_t)msg[4];
+            __attribute__((fallthrough));
+        case 4:
+            lb |= (uint32_t)msg[3] << 24;
+            __attribute__((fallthrough));
+        case 3:
+            lb |= (uint32_t)msg[2] << 16;
+            __attribute__((fallthrough));
+        case 2:
+            lb |= (uint32_t)msg[1] << 8;
+            __attribute__((fallthrough));
+        default:
+            lb |= (uint32_t)msg[0];
+    }
+    box->TDLR = lb;
+    box->TDHR = hb;
+    box->TDTR = len;
+    box->TIR  = (target_id & 0x7FF) << 21 | CAN_TI0R_TXRQ;
+    return CAN_OK;
+}
+
+void set_flood(CAN_message *msg, int incr){
+    if(incr){ incrflood = 1; return; }
+    incrflood = 0;
+    if(!msg) flood_msg = NULL;
+    else{
+        memcpy(&loc_flood_msg, msg, sizeof(CAN_message));
+        flood_msg = &loc_flood_msg;
+    }
+}
+
+static void can_process_fifo(uint8_t fifo_num){
+    if(fifo_num > 1) return;
+    //LED_on(LED1);
+    CAN_FIFOMailBox_TypeDef *box = &CAN->sFIFOMailBox[fifo_num];
+    volatile uint32_t *RFxR = (fifo_num) ? &CAN->RF1R : &CAN->RF0R;
+#ifdef EBUG
+        SEND(u2str(*RFxR & CAN_RF0R_FMP0)); SENDN(" messages in FIFO");
+#endif
+    // read all
+    while(*RFxR & CAN_RF0R_FMP0){ // amount of messages pending
+        // CAN_RDTxR: (16-31) - timestamp, (8-15) - filter match index, (0-3) - data length
+        /* TODO: check filter match index if more than one ID can receive */
+        CAN_message msg;
+        uint8_t *dat = msg.data;
+        uint8_t len = box->RDTR & 0x0f;
+        msg.length = len;
+        msg.ID = box->RIR >> 21;
+        //msg.filterNo = (box->RDTR >> 8) & 0xff;
+        //msg.fifoNum = fifo_num;
+        if(len){ // message can be without data
+            uint32_t hb = box->RDHR, lb = box->RDLR;
+            switch(len){
+                case 8:
+                    dat[7] = hb>>24;
+                    __attribute__((fallthrough));
+                case 7:
+                    dat[6] = (hb>>16) & 0xff;
+                    __attribute__((fallthrough));
+                case 6:
+                    dat[5] = (hb>>8) & 0xff;
+                    __attribute__((fallthrough));
+                case 5:
+                    dat[4] = hb & 0xff;
+                    __attribute__((fallthrough));
+                case 4:
+                    dat[3] = lb>>24;
+                    __attribute__((fallthrough));
+                case 3:
+                    dat[2] = (lb>>16) & 0xff;
+                    __attribute__((fallthrough));
+                case 2:
+                    dat[1] = (lb>>8) & 0xff;
+                    __attribute__((fallthrough));
+                case 1:
+                    dat[0] = lb & 0xff;
+            }
+        }
+        if(CAN_messagebuf_push(&msg)) return; // error: buffer is full, try later
+        *RFxR |= CAN_RF0R_RFOM0; // release fifo for access to next message
+    }
+    //if(*RFxR & CAN_RF0R_FULL0) *RFxR &= ~CAN_RF0R_FULL0;
+    *RFxR = 0; // clear FOVR & FULL
+}
+
+void usb_lp_can1_rx0_isr(){ // Rx FIFO0 (overrun)
+    if(CAN->RF0R & CAN_RF0R_FOVR0){ // FIFO overrun
+        CAN->RF0R &= ~CAN_RF0R_FOVR0;
+        can_status = CAN_FIFO_OVERRUN;
+    }
+}
+
+void can1_rx1_isr(){ // Rx FIFO1 (overrun)
+    if(CAN->RF1R & CAN_RF1R_FOVR1){
+        CAN->RF1R &= ~CAN_RF1R_FOVR1;
+        can_status = CAN_FIFO_OVERRUN;
+    }
+}
+
+void can1_sce_isr(){ // status changed
+    if(CAN->MSR & CAN_MSR_ERRI){ // Error
+#ifdef EBUG
+        last_err_code = CAN->ESR;
+#endif
+        CAN->MSR &= ~CAN_MSR_ERRI;
+        // request abort for problem mailbox
+        if(CAN->TSR & CAN_TSR_TERR0) CAN->TSR |= CAN_TSR_ABRQ0;
+        if(CAN->TSR & CAN_TSR_TERR1) CAN->TSR |= CAN_TSR_ABRQ1;
+        if(CAN->TSR & CAN_TSR_TERR2) CAN->TSR |= CAN_TSR_ABRQ2;
+        can_status = CAN_ERR;
+    }
+}
diff --git a/F3:F303/Seven_CDCs/can.h b/F3:F303/Seven_CDCs/can.h
new file mode 100644
index 0000000..b6720c0
--- /dev/null
+++ b/F3:F303/Seven_CDCs/can.h
@@ -0,0 +1,59 @@
+/*
+ * This file is part of the 7CDCs project.
+ * 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
+
+#include <stdint.h>
+
+// amount of filter banks in STM32F0
+#define STM32F0FBANKNO      28
+// flood period in milliseconds
+#define FLOOD_PERIOD_MS     5
+
+// incoming message buffer size
+#define CAN_INMESSAGE_SIZE  (8)
+extern uint32_t floodT;
+
+// CAN message
+typedef struct{
+    uint8_t data[8];    // up to 8 bytes of data
+    uint8_t length;     // data length
+    uint16_t ID;        // ID of receiver
+} CAN_message;
+
+typedef enum{
+    CAN_STOP,
+    CAN_READY,
+    CAN_BUSY,
+    CAN_OK,
+    CAN_ERR,
+    CAN_FIFO_OVERRUN
+} CAN_status;
+
+CAN_status CAN_get_status();
+
+void CAN_reinit(uint16_t speed);
+void CAN_setup(uint16_t speed);
+
+CAN_status can_send(uint8_t *msg, uint8_t len, uint16_t target_id);
+void can_proc();
+void printCANerr();
+
+CAN_message *CAN_messagebuf_pop();
+
+void set_flood(CAN_message *msg, int incr);
diff --git a/F3:F303/Seven_CDCs/canproto.c b/F3:F303/Seven_CDCs/canproto.c
new file mode 100644
index 0000000..0ac324b
--- /dev/null
+++ b/F3:F303/Seven_CDCs/canproto.c
@@ -0,0 +1,438 @@
+/*
+ * This file is part of the canusb project.
+ * 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 <stm32f3.h>
+#include <string.h>
+
+#include "can.h"
+#include "hardware.h"
+#include "canproto.h"
+#include "version.inc"
+
+#include "usb.h"
+#include "strfunc.h"
+
+#define SEND(str)       do{USB_sendstr(CAN_IDX, str);}while(0)
+#define SENDN(str)      do{USB_sendstr(CAN_IDX, str); USB_putbyte(CAN_IDX, '\n');}while(0)
+#define printu(x)       SEND(u2str(x))
+#define printuhex(x)    SEND(uhex2str(x))
+
+// software ignore buffer size
+#define IGN_SIZE 10
+
+extern volatile uint32_t Tms;
+
+uint8_t ShowMsgs = 1;
+// software ignore buffers
+static uint16_t Ignore_IDs[IGN_SIZE];
+static uint8_t IgnSz = 0;
+
+// parse `txt` to CAN_message
+static CAN_message *parseCANmsg(const char *txt){
+    static CAN_message canmsg;
+    uint32_t N;
+    int ctr = -1;
+    canmsg.ID = 0xffff;
+    do{
+        const char *n = getnum(txt, &N);
+        if(txt == n) break;
+        txt = n;
+        if(ctr == -1){
+            if(N > 0x7ff){
+                SENDN("ID should be 11-bit number!");
+                return NULL;
+            }
+            canmsg.ID = (uint16_t)(N&0x7ff);
+            ctr = 0;
+            continue;
+        }
+        if(ctr > 7){
+            SENDN("ONLY 8 data bytes allowed!");
+            return NULL;
+        }
+        if(N > 0xff){
+            SENDN("Every data portion is a byte!");
+            return NULL;
+        }
+        canmsg.data[ctr++] = (uint8_t)(N&0xff);
+    }while(1);
+    if(canmsg.ID == 0xffff){
+        SENDN("NO ID given, send nothing!");
+        return NULL;
+    }
+    SENDN("Message parsed OK");
+    canmsg.length = (uint8_t) ctr;
+    return &canmsg;
+}
+
+// USB_sendstr command, format: ID (hex/bin/dec) data bytes (up to 8 bytes, space-delimeted)
+TRUE_INLINE void USB_sendstrCANcommand(char *txt){
+    if(CAN->MSR & CAN_MSR_INAK){
+        SENDN("CAN bus is off, try to restart it");
+        return;
+    }
+    CAN_message *msg = parseCANmsg(txt);
+    if(!msg) return;
+    uint32_t N = 5;
+    while(CAN_BUSY == can_send(msg->data, msg->length, msg->ID)){
+        if(--N == 0) break;
+    }
+}
+
+TRUE_INLINE void CANini(const char *txt){
+    uint32_t N;
+    const char *n = getnum(txt, &N);
+    if(txt == n){
+        SEND("No speed given");
+        return;
+    }
+    if(N < 50){
+        SEND("Lowest speed is 50kbps");
+        return;
+    }else if(N > 3000){
+        SEND("Highest speed is 3000kbps");
+        return;
+    }
+    CAN_reinit((uint16_t)N);
+    SEND("Reinit CAN bus with speed ");
+    printu(N); SENDN("kbps");
+}
+
+TRUE_INLINE void addIGN(const char *txt){
+    if(IgnSz == IGN_SIZE){
+        SENDN("Ignore buffer is full");
+        return;
+    }
+    txt = omit_spaces(txt);
+    uint32_t N;
+    const char *n = getnum(txt, &N);
+    if(txt == n){
+        SENDN("No ID given");
+        return;
+    }
+    if(N > 0x7ff){
+        SENDN("ID should be 11-bit number!");
+        return;
+    }
+    Ignore_IDs[IgnSz++] = (uint16_t)(N & 0x7ff);
+    SEND("Added ID "); printu(N);
+    SENDN("\nIgn buffer size: "); SENDN(u2str(IgnSz));
+}
+
+TRUE_INLINE void print_ign_buf(){
+    if(IgnSz == 0){
+        SENDN("Ignore buffer is empty");
+        return;
+    }
+    SENDN("Ignored IDs:");
+    for(int i = 0; i < IgnSz; ++i){
+        printu(i);
+        SEND(": ");
+        SENDN(u2str(Ignore_IDs[i]));
+    }
+}
+
+// print ID/mask of CAN->sFilterRegister[x] half
+static void printID(uint16_t FRn){
+    if(FRn & 0x1f) return; // trash
+    printuhex(FRn >> 5);
+}
+/*
+Can filtering: FSCx=0 (CAN->FS1R) -> 16-bit identifiers
+CAN->FMR = (sb)<<8 | FINIT - init filter in starting bank sb
+CAN->FFA1R FFAx = 1 -> FIFO1, 0 -> FIFO0
+CAN->FA1R FACTx=1 - filter active
+MASK: FBMx=0 (CAN->FM1R), two filters (n in FR1 and n+1 in FR2)
+    ID:   CAN->sFilterRegister[x].FRn[0..15]
+    MASK: CAN->sFilterRegister[x].FRn[16..31]
+    FR bits:  STID[10:0] RTR IDE EXID[17:15]
+LIST: FBMx=1, four filters (n&n+1 in FR1, n+2&n+3 in FR2)
+    IDn:   CAN->sFilterRegister[x].FRn[0..15]
+    IDn+1: CAN->sFilterRegister[x].FRn[16..31]
+*/
+TRUE_INLINE void list_filters(){
+    uint32_t fa = CAN->FA1R, ctr = 0, mask = 1;
+    while(fa){
+        if(fa & 1){
+            SEND("Filter "); printu(ctr); SEND(", FIFO");
+            if(CAN->FFA1R & mask) SEND("1");
+            else SEND("0");
+            SEND(" in ");
+            if(CAN->FM1R & mask){ // up to 4 filters in LIST mode
+                SEND("LIST mode, IDs: ");
+                printID(CAN->sFilterRegister[ctr].FR1 & 0xffff);
+                SEND(" ");
+                printID(CAN->sFilterRegister[ctr].FR1 >> 16);
+                SEND(" ");
+                printID(CAN->sFilterRegister[ctr].FR2 & 0xffff);
+                SEND(" ");
+                printID(CAN->sFilterRegister[ctr].FR2 >> 16);
+            }else{ // up to 2 filters in MASK mode
+                SEND("MASK mode: ");
+                if(!(CAN->sFilterRegister[ctr].FR1&0x1f)){
+                    SEND("ID="); printID(CAN->sFilterRegister[ctr].FR1 & 0xffff);
+                    SEND(", MASK="); printID(CAN->sFilterRegister[ctr].FR1 >> 16);
+                    SEND(" ");
+                }
+                if(!(CAN->sFilterRegister[ctr].FR2&0x1f)){
+                    SEND("ID="); printID(CAN->sFilterRegister[ctr].FR2 & 0xffff);
+                    SEND(", MASK="); printID(CAN->sFilterRegister[ctr].FR2 >> 16);
+                }
+            }
+            SEND("\n");
+        }
+        fa >>= 1;
+        ++ctr;
+        mask <<= 1;
+    }
+}
+
+TRUE_INLINE void setfloodt(const char *s){
+    uint32_t N;
+    s = omit_spaces(s);
+    const char *n = getnum(s, &N);
+    if(s == n){
+        SENDN("t="); SENDN(u2str(floodT));
+        return;
+    }
+    floodT = N;
+}
+
+/**
+ * @brief add_filter - add/modify filter
+ * @param str - string in format "bank# FIFO# mode num0 .. num3"
+ * where bank# - 0..27
+ * if there's nothing after bank# - delete filter
+ * FIFO# - 0,1
+ * mode - 'I' for ID, 'M' for mask
+ * num0..num3 - IDs in ID mode, ID/MASK for mask mode
+ */
+static void add_filter(const char *str){
+    uint32_t N;
+    str = omit_spaces(str);
+    const char *n = getnum(str, &N);
+    if(n == str){
+        SENDN("No bank# given");
+        return;
+    }
+    if(N > STM32F0FBANKNO-1){
+        SENDN("bank# > 27");
+        return;
+    }
+    uint8_t bankno = (uint8_t)N;
+    str = omit_spaces(n);
+    if(!*str){ // deactivate filter
+        SEND("Deactivate filters in bank ");
+        printu(bankno);
+        SEND("\n");
+        CAN->FMR = CAN_FMR_FINIT;
+        CAN->FA1R &= ~(1<<bankno);
+        CAN->FMR &=~ CAN_FMR_FINIT;
+        return;
+    }
+    uint8_t fifono = 0;
+    if(*str == '1') fifono = 1;
+    else if(*str != '0'){
+        SENDN("FIFO# is 0 or 1");
+        return;
+    }
+    str = omit_spaces(str + 1);
+    const char c = *str;
+    uint8_t mode = 0; // ID
+    if(c == 'M' || c == 'm') mode = 1;
+    else if(c != 'I' && c != 'i'){
+        SENDN("mode is 'M/m' for MASK and 'I/i' for IDLIST");
+        return;
+    }
+    str = omit_spaces(str + 1);
+    uint32_t filters[4];
+    uint32_t nfilt;
+    for(nfilt = 0; nfilt < 4; ++nfilt){
+        n = getnum(str, &N);
+        if(n == str) break;
+        filters[nfilt] = N;
+        str = omit_spaces(n);
+    }
+    if(nfilt == 0){
+        SENDN("You should add at least one filter!");
+        return;
+    }
+    if(mode && (nfilt&1)){
+        SENDN("In MASK mode you should point pairs of ID/MASK");
+        return;
+    }
+    CAN->FMR = CAN_FMR_FINIT;
+    uint32_t mask = 1<<bankno;
+    CAN->FA1R |= mask; // activate given filter
+    if(fifono) CAN->FFA1R |= mask; // set FIFO number
+    else CAN->FFA1R &= ~mask;
+    if(mode) CAN->FM1R &= ~mask; // MASK
+    else CAN->FM1R |= mask; // LIST
+    uint32_t F1 = (0x8f<<16);
+    uint32_t F2 = (0x8f<<16);
+    // reset filter registers to wrong value
+    CAN->sFilterRegister[bankno].FR1 = (0x8f<<16) | 0x8f;
+    CAN->sFilterRegister[bankno].FR2 = (0x8f<<16) | 0x8f;
+    switch(nfilt){
+        case 4:
+            F2 = filters[3] << 21;
+            // fallthrough
+        case 3:
+            CAN->sFilterRegister[bankno].FR2 = (F2 & 0xffff0000) | (filters[2] << 5);
+            // fallthrough
+        case 2:
+            F1 = filters[1] << 21;
+            // fallthrough
+        case 1:
+            CAN->sFilterRegister[bankno].FR1 = (F1 & 0xffff0000) | (filters[0] << 5);
+    }
+    CAN->FMR &=~ CAN_FMR_FINIT;
+    SEND("Added filter with ");
+    printu(nfilt); SENDN(" parameters");
+}
+
+static const char *helpstring =
+    "https://github.com/eddyem/stm32samples/tree/master/F3:F303/Seven_CDCs build#" BUILD_NUMBER " @ " BUILD_DATE "\n"
+    "'a' - add ID to ignore list (max 10 IDs)\n"
+    "'b' - reinit CAN with given baudrate\n"
+    "'c' - get CAN status\n"
+    "'d' - delete ignore list\n"
+    "'e' - get CAN errcodes\n"
+    "'f' - add/delete filter, format: bank# FIFO# mode(M/I) num0 [num1 [num2 [num3]]]\n"
+    "'F' - send/clear flood message: F ID byte0 ... byteN\n"
+    "'i' - send incremental flood message (ID == ID for `F`)\n"
+    "'I' - reinit CAN\n"
+    "'l' - list all active filters\n"
+//    "'o' - turn LEDs OFF\n"
+//    "'O' - turn LEDs ON\n"
+    "'p' - print ignore buffer\n"
+    "'P' - pause/resume in packets displaying\n"
+    "'R' - software reset\n"
+    "'s/S' - send data over CAN: s ID byte0 .. byteN\n"
+    "'t' - change flood period (>=0ms)\n"
+    "'T' - get time from start (ms)\n"
+;
+
+
+TRUE_INLINE void getcanstat(){
+    SEND("CAN_MSR=");
+    printuhex(CAN->MSR);
+    SEND("\nCAN_TSR=");
+    printuhex(CAN->TSR);
+    SEND("\nCAN_RF0R=");
+    printuhex(CAN->RF0R);
+    SEND("\nCAN_RF1R=");
+    SENDN(u2str(CAN->RF1R));
+}
+
+/**
+ * @brief cmd_parser - command parsing
+ * @param txt   - buffer with commands & data
+ * @param isUSB - == 1 if data got from USB
+ */
+void cmd_parser(char *txt){
+    char _1st = txt[0];
+    ++txt;
+    /*
+     * parse long commands here
+     */
+    switch(_1st){
+        case 'a':
+            addIGN(txt);
+            return;
+        break;
+        case 'b':
+            CANini(txt);
+            return;
+        break;
+        case 'f':
+            add_filter(txt);
+            return;
+        break;
+        case 'F':
+            set_flood(parseCANmsg(txt), 0);
+            return;
+        break;
+        case 's':
+        case 'S':
+            USB_sendstrCANcommand(txt);
+            return;
+        break;
+        case 't':
+            setfloodt(txt);
+            return;
+        break;
+    }
+    if(*txt) _1st = '?'; // help for wrong message length
+    switch(_1st){
+        case 'c':
+            getcanstat();
+        break;
+        case 'd':
+            IgnSz = 0;
+        break;
+        case 'e':
+            printCANerr();
+        break;
+        case 'i':
+            set_flood(NULL, 1);
+            SENDN("Incremental flooding is ON ('F' to off)");
+        break;
+        case 'I':
+            CAN_reinit(0);
+        break;
+        case 'l':
+            list_filters();
+        break;
+/*        case 'o':
+            ledsON = 0;
+            LED_off(LED0);
+            LED_off(LED1);
+        break;
+        case 'O':
+            ledsON = 1;
+        break;*/
+        case 'p':
+            print_ign_buf();
+        break;
+        case 'P':
+            ShowMsgs = !ShowMsgs;
+            if(ShowMsgs) SENDN("Resume");
+            else SENDN("Pause");
+        break;
+        case 'R':
+            SENDN("Soft reset");
+            USB_sendall(CAN_IDX); // wait until everything will gone
+            NVIC_SystemReset();
+        break;
+        case 'T':
+            SEND("Time (ms): ");
+            SENDN(u2str(Tms));
+        break;
+        default: // help
+            SENDN(helpstring);
+        break;
+    }
+}
+
+// check Ignore_IDs & return 1 if ID isn't in list
+uint8_t isgood(uint16_t ID){
+    for(int i = 0; i < IgnSz; ++i)
+        if(Ignore_IDs[i] == ID) return 0;
+    return 1;
+}
diff --git a/F3:F303/Seven_CDCs/canproto.h b/F3:F303/Seven_CDCs/canproto.h
new file mode 100644
index 0000000..1e5c05c
--- /dev/null
+++ b/F3:F303/Seven_CDCs/canproto.h
@@ -0,0 +1,26 @@
+/*
+ * This file is part of the canusb project.
+ * 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
+
+#include <stdint.h>
+
+extern uint8_t ShowMsgs; // show CAN messages flag
+
+void cmd_parser(char *txt);
+uint8_t isgood(uint16_t ID);
diff --git a/F3:F303/Seven_CDCs/cmdproto.c b/F3:F303/Seven_CDCs/cmdproto.c
index 0776302..af8346a 100644
--- a/F3:F303/Seven_CDCs/cmdproto.c
+++ b/F3:F303/Seven_CDCs/cmdproto.c
@@ -19,6 +19,7 @@
 #include "cmdproto.h"
 #include "debug.h"
 #include "strfunc.h"
+#include "usart.h"
 #include "usb.h"
 #include "usb_lib.h" // USBON
 #include "version.inc"
@@ -28,12 +29,13 @@
 
 extern volatile uint32_t Tms;
 
-const char* helpmsg =
-    "https://github.com/eddyem/stm32samples/tree/master/F3:F303/PL2303 build#" BUILD_NUMBER " @ " BUILD_DATE "\n"
+static const char* helpmsg =
+    "https://github.com/eddyem/stm32samples/tree/master/F3:F303/Seven_CDCs build#" BUILD_NUMBER " @ " BUILD_DATE "\n"
     "2..7 - send next string to given EP\n"
     "'i' - print USB->ISTR state\n"
     "'N' - read number (dec, 0xhex, 0oct, bbin) and show it in decimal\n"
     "'R' - software reset\n"
+    "'ux data' - send data to USARTx\n"
     "'U' - get USB status\n"
     "'W' - test watchdog\n"
 ;
@@ -94,6 +96,15 @@ void parse_cmd(const char *buf){
                 SEND(nxt);
             }else SEND("\n");
         break;
+        case 'u':
+            nxt = getnum(buf, &Num);
+            if(buf == nxt || Num < 1 || Num > USARTSNO){
+                if(Num == 0) SENDN("Wrong USART number");
+            }
+            nxt = omit_spaces(nxt);
+            usart_sendn(Num, (uint8_t*)nxt, mystrlen(nxt));
+            SENDN("OK");
+        break;
         default:
             SEND(buf-1); // echo
             return;
diff --git a/F3:F303/Seven_CDCs/hardware.c b/F3:F303/Seven_CDCs/hardware.c
index 00e2f48..44dc333 100644
--- a/F3:F303/Seven_CDCs/hardware.c
+++ b/F3:F303/Seven_CDCs/hardware.c
@@ -19,19 +19,44 @@
 #include "hardware.h"
 #include "usart.h"
 
+TRUE_INLINE void iwdg_setup(){
+    uint32_t tmout = 16000000;
+    /* Enable the peripheral clock RTC */
+    /* (1) Enable the LSI (40kHz) */
+    /* (2) Wait while it is not ready */
+    RCC->CSR |= RCC_CSR_LSION; /* (1) */
+    while((RCC->CSR & RCC_CSR_LSIRDY) != RCC_CSR_LSIRDY){if(--tmout == 0) break;} /* (2) */
+    /* Configure IWDG */
+    /* (1) Activate IWDG (not needed if done in option bytes) */
+    /* (2) Enable write access to IWDG registers */
+    /* (3) Set prescaler by 64 (1.6ms for each tick) */
+    /* (4) Set reload value to have a rollover each 2s */
+    /* (5) Check if flags are reset */
+    /* (6) Refresh counter */
+    IWDG->KR = IWDG_START; /* (1) */
+    IWDG->KR = IWDG_WRITE_ACCESS; /* (2) */
+    IWDG->PR = IWDG_PR_PR_1; /* (3) */
+    IWDG->RLR = 1250; /* (4) */
+    tmout = 16000000;
+    while(IWDG->SR){if(--tmout == 0) break;} /* (5) */
+    IWDG->KR = IWDG_REFRESH; /* (6) */
+}
+
+
 static inline void gpio_setup(){
     RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
-    // LEDs on PB0 and PB1
-    GPIOB->MODER = GPIO_MODER_MODER0_O | GPIO_MODER_MODER1_O;
-    GPIOB->ODR = 1;
     // USB - alternate function 14 @ pins PA11/PA12; USART1 = AF7 @PA9/10; SWD - AF0 @PA13/14
     GPIOA->AFR[1] = AFRf(7, 9) | AFRf(7, 10) | AFRf(14, 11) | AFRf(14, 12);
     // USART1: PA10(Rx), PA9(Tx); USB - PA11, PA12; SWDIO - PA13, PA14; Pullup - PA15
     GPIOA->MODER = MODER_AF(9) | MODER_AF(10) | MODER_AF(11) | MODER_AF(12) | MODER_AF(13) | MODER_AF(14) | MODER_O(15);
     GPIOA->OSPEEDR = OSPEED_HI(11) | OSPEED_HI(12) | OSPEED_HI(13) | OSPEED_HI(14);
+    // LEDs on PB0 and PB1
+    GPIOB->MODER = GPIO_MODER_MODER0_O | GPIO_MODER_MODER1_O;
+    GPIOB->ODR = 1;
 }
 
 void hw_setup(){
     gpio_setup();
+    iwdg_setup();
 }
 
diff --git a/F3:F303/Seven_CDCs/main.c b/F3:F303/Seven_CDCs/main.c
index 3871534..a286234 100644
--- a/F3:F303/Seven_CDCs/main.c
+++ b/F3:F303/Seven_CDCs/main.c
@@ -16,6 +16,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "can.h"
+#include "canproto.h"
 #include "cmdproto.h"
 #include "debug.h"
 #include "hardware.h"
@@ -46,17 +48,40 @@ int main(void){
     hw_setup();
     usarts_setup();
     USB_setup();
+    CAN_setup(100);
     USBPU_ON();
 
+    CAN_message *can_mesg;
     uint32_t ctr = Tms;
     while(1){
+        IWDG->KR = IWDG_REFRESH;
         if(Tms - ctr > 499){
             ctr = Tms;
             pin_toggle(GPIOB, 1 << 1 | 1 << 0); // toggle LED @ PB0
-            USB_sendstr(CMD_IDX, "1");
+            //USB_sendstr(CMD_IDX, "1");
             //DBGmesg(u2str(Tms));
             //DBGnl();
         }
+        can_proc();
+        if(CAN_get_status() == CAN_FIFO_OVERRUN){
+            USB_sendstr(CAN_IDX, "CAN bus fifo overrun occured!\n");
+        }
+        while((can_mesg = CAN_messagebuf_pop())){
+            if(isgood(can_mesg->ID)){
+                if(ShowMsgs){ // display message content
+                    IWDG->KR = IWDG_REFRESH;
+                    uint8_t len = can_mesg->length;
+                    USB_sendstr(CAN_IDX, u2str(Tms));
+                    USB_sendstr(CAN_IDX, " #");
+                    USB_sendstr(CAN_IDX, uhex2str(can_mesg->ID));
+                    for(uint8_t i = 0; i < len; ++i){
+                        USB_putbyte(CAN_IDX, ' ');
+                        USB_sendstr(CAN_IDX, uhex2str(can_mesg->data[i]));
+                    }
+                    USB_putbyte(CAN_IDX, '\n');
+                }
+            }
+        }
         for(int i = 0; i < MAX_IDX; ++i){
             int l = USB_receivestr(i, inbuff, MAXSTRLEN);
             if(l < 0){
@@ -73,6 +98,9 @@ int main(void){
                 case CMD_IDX:
                     parse_cmd(inbuff);
                 break;
+                case CAN_IDX:
+                    cmd_parser(inbuff);
+                break;
                 default:
                 break;
             }
diff --git a/F3:F303/Seven_CDCs/sevenCDCs.bin b/F3:F303/Seven_CDCs/sevenCDCs.bin
index 9329eaa..3e90e6b 100755
Binary files a/F3:F303/Seven_CDCs/sevenCDCs.bin and b/F3:F303/Seven_CDCs/sevenCDCs.bin differ
diff --git a/F3:F303/Seven_CDCs/strfunc.c b/F3:F303/Seven_CDCs/strfunc.c
index 69f10ea..614b263 100644
--- a/F3:F303/Seven_CDCs/strfunc.c
+++ b/F3:F303/Seven_CDCs/strfunc.c
@@ -268,6 +268,13 @@ const char *getint(const char *txt, int32_t *I){
     return nxt;
 }
 
+int mystrlen(const char *txt){
+    if(!txt) return 0;
+    int r = 0;
+    while(*txt++) ++r;
+    return r;
+}
+
 /*
 void mymemcpy(char *dest, const char *src, int len){
     if(len < 1) return;
diff --git a/F3:F303/Seven_CDCs/strfunc.h b/F3:F303/Seven_CDCs/strfunc.h
index fc61644..e1dd59e 100644
--- a/F3:F303/Seven_CDCs/strfunc.h
+++ b/F3:F303/Seven_CDCs/strfunc.h
@@ -28,5 +28,6 @@ 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);
+int mystrlen(const char *txt);
 //void mymemcpy(char *dest, const char *src, int len);
 char * float2str(float x, uint8_t prec);
diff --git a/F3:F303/Seven_CDCs/usb.c b/F3:F303/Seven_CDCs/usb.c
index 9129679..781cc53 100644
--- a/F3:F303/Seven_CDCs/usb.c
+++ b/F3:F303/Seven_CDCs/usb.c
@@ -19,6 +19,7 @@
 #include <string.h>
 
 #include "hardware.h"
+#include "strfunc.h"
 #include "usb.h"
 #include "usb_lib.h"
 
@@ -89,12 +90,8 @@ int USB_putbyte(int ifNo, uint8_t byte){
 }
 
 int USB_sendstr(int ifNo, const char *string){
-    if(!string || !USBON(ifNo)) return 0;
-    int len = 0;
-    const char *b = string;
-    while(*b++) ++len;
-    if(!len) return 0;
-    return USB_send(ifNo, (const uint8_t*)string, len);
+    if(!string) return 0;
+    return USB_send(ifNo, (const uint8_t*)string, mystrlen(string));
 }
 
 /**
diff --git a/F3:F303/Seven_CDCs/usb_lib.c b/F3:F303/Seven_CDCs/usb_lib.c
index 3b8067d..ac0f04e 100644
--- a/F3:F303/Seven_CDCs/usb_lib.c
+++ b/F3:F303/Seven_CDCs/usb_lib.c
@@ -775,9 +775,8 @@ static void rxtx_Handler(uint8_t epno){
                 case USART4_EPNO:
                     ; // we have no USART4 in STM32F303CBT6
                 break;
-                default:
-                    if(RB_write((ringbuffer*)&rbin[idx], buf, sz) != sz) bufovrfl[idx] = 1;
             }
+            if(RB_write((ringbuffer*)&rbin[idx], buf, sz) != sz) bufovrfl[idx] = 1;
         }
         // set ACK Rx
         USB->EPnR[epno] = (KEEP_DTOG(USB->EPnR[epno]) & ~(USB_EPnR_STAT_TX)) ^ USB_EPnR_STAT_RX;
diff --git a/F3:F303/Seven_CDCs/version.inc b/F3:F303/Seven_CDCs/version.inc
index c982bd1..a050ec6 100644
--- a/F3:F303/Seven_CDCs/version.inc
+++ b/F3:F303/Seven_CDCs/version.inc
@@ -1,2 +1,2 @@
-#define BUILD_NUMBER "122"
+#define BUILD_NUMBER "133"
 #define BUILD_DATE "2023-04-29"