diff --git a/F3:F303/CANbus4BTA/BTA_CAN.bin b/F3:F303/CANbus4BTA/BTA_CAN.bin
index c030ba8..1f55b85 100755
Binary files a/F3:F303/CANbus4BTA/BTA_CAN.bin and b/F3:F303/CANbus4BTA/BTA_CAN.bin differ
diff --git a/F3:F303/CANbus4BTA/can.c b/F3:F303/CANbus4BTA/can.c
index 3be9089..94cec5e 100644
--- a/F3:F303/CANbus4BTA/can.c
+++ b/F3:F303/CANbus4BTA/can.c
@@ -32,6 +32,15 @@
 
 #include <string.h> // memcpy
 
+// CAN bus oscillator frequency: 36MHz
+#define CAN_F_OSC       (36000000UL)
+// timing values TBS1 and TBS2 (in BTR [TBS1-1] and [TBS2-1])
+// use 3 and 2 to get 6MHz
+#define CAN_TBS1    (3)
+#define CAN_TBS2    (2)
+// bitrate oscillator frequency
+#define CAN_BIT_OSC (CAN_F_OSC / (1+CAN_TBS1+CAN_TBS2))
+
 uint8_t cansniffer = 0; // 0 - receive only 0 and myID, 1 - receive all
 
 // circular buffer for  received messages
@@ -143,7 +152,7 @@ void CAN_setup(uint32_t speed){
     /* (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 */
+    /* (4) Normal mode, set timing : TBS1 = 4, TBS2 = 3 */
     /* (5) Leave init mode */
     /* (6) Wait the init mode leaving */
     /* (7) Enter filter init mode, (16-bit + mask, bank 0 for FIFO 0) */
@@ -158,8 +167,8 @@ void CAN_setup(uint32_t speed){
     if(tmout==0){ DBG("timeout!\n");}
     CAN->MCR &=~ CAN_MCR_SLEEP; /* (3) */
     CAN->MCR |= CAN_MCR_ABOM; /* allow automatically bus-off */
-    CAN->BTR =  2 << 20 | 3 << 16 | (((uint32_t)4500000UL)/speed - 1); //| CAN_BTR_SILM | CAN_BTR_LBKM; /* (4) */
-    oldspeed = ((uint32_t)4500000UL)/(uint32_t)((CAN->BTR & CAN_BTR_BRP) + 1);
+    CAN->BTR =  (CAN_TBS2-1) << 20 | (CAN_TBS1-1) << 16 | (CAN_BIT_OSC/speed - 1); //| CAN_BTR_SILM | CAN_BTR_LBKM; /* (4) */
+    oldspeed = CAN_BIT_OSC/(uint32_t)((CAN->BTR & CAN_BTR_BRP) + 1);
     CAN->MCR &= ~CAN_MCR_INRQ; /* (5) */
     tmout = 10000;
     while(CAN->MSR & CAN_MSR_INAK) /* (6) */
diff --git a/F3:F303/CANbus4BTA/canbus4bta.creator.user b/F3:F303/CANbus4BTA/canbus4bta.creator.user
index 332da69..b114d45 100644
--- a/F3:F303/CANbus4BTA/canbus4bta.creator.user
+++ b/F3:F303/CANbus4BTA/canbus4bta.creator.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 12.0.1, 2024-01-07T00:44:38. -->
+<!-- Written by QtCreator 12.0.1, 2024-01-08T22:45:09. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>
diff --git a/F3:F303/CANbus4BTA/canbus4bta.files b/F3:F303/CANbus4BTA/canbus4bta.files
index 9930bb6..4478816 100644
--- a/F3:F303/CANbus4BTA/canbus4bta.files
+++ b/F3:F303/CANbus4BTA/canbus4bta.files
@@ -6,6 +6,8 @@ commonfunctions.c
 commonfunctions.h
 flash.c
 flash.h
+gpio.c
+gpio.h
 hardware.c
 hardware.h
 main.c
diff --git a/F3:F303/CANbus4BTA/commonfunctions.c b/F3:F303/CANbus4BTA/commonfunctions.c
index 46dd599..f4a828c 100644
--- a/F3:F303/CANbus4BTA/commonfunctions.c
+++ b/F3:F303/CANbus4BTA/commonfunctions.c
@@ -20,6 +20,7 @@
 #include "can.h"
 #include "commonfunctions.h"
 #include "flash.h"
+#include "gpio.h"
 #include "proto.h"
 #include "usb.h"
 
@@ -102,7 +103,39 @@ static errcodes erasestor(CAN_message _U_ *msg){
     if(0 == erase_storage(-1)) return ERR_OK;
     return ERR_CANTRUN;
 }
-
+// relay management
+static errcodes relay(CAN_message *msg){
+    if(ISSETTER(msg->data)){
+        if(msg->data[4] == 1) RELAY_ON();
+        else RELAY_OFF();
+    }else FIXDL(msg);
+    *(uint32_t*)&msg->data[4] = RELAY_GET();
+    return ERR_OK;
+}
+// blocking ESW get status
+static errcodes eswblk(CAN_message *msg){
+    uint8_t no = msg->data[2] & ~SETTER_FLAG;
+    if(no > 1) return ERR_BADPAR;
+    FIXDL(msg);
+    *(uint32_t*)&msg->data[4] = getSwitches(no);
+    return ERR_OK;
+}
+// bounce-free ESW get status
+static errcodes esw(CAN_message *msg){
+    uint8_t no = msg->data[2] & ~SETTER_FLAG;
+    if(no > 1) return ERR_BADPAR;
+    FIXDL(msg);
+    *(uint32_t*)&msg->data[4] = getESW(no);
+    return ERR_OK;
+}
+// bounce constant, ms
+static errcodes bounce(CAN_message *msg){
+    if(ISSETTER(msg->data)){
+        the_conf.bounce_ms = *(uint32_t*)&msg->data[4];
+    }else FIXDL(msg);
+    *(uint32_t*)&msg->data[4] = the_conf.bounce_ms;
+    return ERR_OK;
+}
 /************ END of all common functions list (for `funclist`) ************/
 
 
@@ -126,6 +159,10 @@ static const commonfunction funclist[CMD_AMOUNT] = {
     [CMD_ADCMUL] = {adcmul, 0, 0, 3}, // at least parno
     [CMD_SAVECONF] = {saveconf, 0, 0, 0},
     [CMD_ERASESTOR] = {erasestor, 0, 0, 0},
+    [CMD_RELAY] = {relay, 0, 1, 0},
+    [CMD_GETESW_BLK] = {eswblk, 0, 0, 3},
+    [CMD_GETESW] = {esw, 0, 0, 3},
+    [CMD_BOUNCE] = {bounce, 0, 300, 0},
 };
 
 
diff --git a/F3:F303/CANbus4BTA/flash.c b/F3:F303/CANbus4BTA/flash.c
index d4366f8..5976917 100644
--- a/F3:F303/CANbus4BTA/flash.c
+++ b/F3:F303/CANbus4BTA/flash.c
@@ -35,6 +35,7 @@ static uint32_t maxCnum = 1024 / sizeof(user_conf); // can't use blocksize here
      .userconf_sz = sizeof(user_conf)       \
     ,.CANspeed = 100000                     \
     ,.CANID = 0xaa                          \
+    ,.bounce = 50                           \
     ,.adcmul[0] = 10.930f                   \
     ,.adcmul[1] = 2.028f                    \
     ,.adcmul[2] = 1.f                       \
diff --git a/F3:F303/CANbus4BTA/flash.h b/F3:F303/CANbus4BTA/flash.h
index 5e1b871..4f5730f 100644
--- a/F3:F303/CANbus4BTA/flash.h
+++ b/F3:F303/CANbus4BTA/flash.h
@@ -35,6 +35,7 @@ typedef struct __attribute__((packed, aligned(4))){
     uint16_t userconf_sz;           // "magick number"
     uint16_t CANID;                 // identifier
     uint32_t CANspeed;              // default CAN speed
+    uint32_t bounce_ms;              // a
     float adcmul[ADC_TSENS];        // ADC voltage multipliers
 } user_conf;
 
diff --git a/F3:F303/CANbus4BTA/gpio.c b/F3:F303/CANbus4BTA/gpio.c
new file mode 100644
index 0000000..acc15a0
--- /dev/null
+++ b/F3:F303/CANbus4BTA/gpio.c
@@ -0,0 +1,102 @@
+/*
+ * This file is part of the canbus4bta project.
+ * 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 "flash.h"
+#include "gpio.h"
+#include "hardware.h"
+
+// GPIO IN management by two 74HC4051
+
+static uint8_t eswitches[2] = {0};
+static uint8_t stage = 0;
+static uint32_t lastT[8][2] = {0};  // last time of ESW changed
+
+uint8_t getESW(uint8_t nch){
+    return eswitches[nch];
+}
+
+// update `eswitches`, anti-bounce
+TRUE_INLINE void updesw(uint8_t nch, uint8_t newval){
+    uint8_t mask = eswitches[nch] ^ newval, newmask = 0;
+    if(mask == 0) return;
+    for(uint8_t bit = 0; bit < 8; ++bit){ // check all bits of mask
+        newmask >>= 1;
+        if((mask & 1) && Tms - lastT[bit][nch] >= the_conf.bounce_ms){ // OK, change this value
+            newmask |= 0x80;
+            lastT[bit][nch] = Tms;
+        }
+        mask >>= 1;
+    }
+    if(newmask == 0) return;
+    // now change only allowable bits
+    eswitches[nch] = (eswitches[nch] & ~newmask) | (newval & newmask);
+}
+
+/**
+ * @brief ESW_process - process multiplexer 1
+ */
+void ESW_process(){
+    static uint8_t curch = 0;
+    static int curaddr = 7;
+    static uint8_t ESW = 0;
+    switch(stage){
+        case 0: // stage 0: change address and turn on multiplexer
+            stage = 1;
+            MULADDR_set(curaddr);
+            MUL_ON(curch);
+        break;
+        case 1: // stage 1: read data and turn off mul
+        default:
+            stage = 0;
+            ESW <<= 1;
+            ESW |= ESW_GET();
+            MUL_OFF(curch);
+            if(--curaddr < 0){
+                updesw(curch, ESW);
+                curch = !curch;
+                curaddr = 7;
+            }
+        break;
+    }
+}
+
+static void NeverDoThisFuckingShit(){
+    uint32_t ctr = 3;
+    while(ctr--) nop();
+}
+
+/**
+ * @brief getSwitches - blocking read of all switches of given channel
+ * @param chno - number of multiplexer: 0 (board switches) or 1 (external ESW)
+ */
+uint8_t getSwitches(uint8_t chno){
+    if(chno > 1) return 0;
+    MUL_OFF(0); MUL_OFF(1);
+    uint8_t state = 0;
+    for(int i = 7; i > -1; --i){
+        MULADDR_set(i);
+        MUL_ON(chno);
+        state <<= 1;
+        NeverDoThisFuckingShit();
+        state |= ESW_GET();
+        MUL_OFF(chno);
+        NeverDoThisFuckingShit();
+    }
+    stage = 0; // prevent interference with `ESW_process()`
+    return state;
+}
diff --git a/F3:F303/CANbus4BTA/gpio.h b/F3:F303/CANbus4BTA/gpio.h
new file mode 100644
index 0000000..2b63608
--- /dev/null
+++ b/F3:F303/CANbus4BTA/gpio.h
@@ -0,0 +1,24 @@
+/*
+ * This file is part of the canbus4bta project.
+ * 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>
+
+uint8_t getESW(uint8_t nch);
+void ESW_process();
+uint8_t getSwitches(uint8_t chno);
diff --git a/F3:F303/CANbus4BTA/hardware.c b/F3:F303/CANbus4BTA/hardware.c
index fa04be3..2836d52 100644
--- a/F3:F303/CANbus4BTA/hardware.c
+++ b/F3:F303/CANbus4BTA/hardware.c
@@ -47,6 +47,7 @@ TRUE_INLINE void iwdg_setup(){
 #endif
 
 static inline void gpio_setup(){
+    RELAY_OFF(); MUL_OFF(0); MUL_OFF(1);
     RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN | RCC_AHBENR_GPIOCEN;
     // PWM - AF1 @PA7; USB - alternate function 14 @ pins PA11/PA12; USART1 = AF7 @PA9/10; SWD - AF0 @PA13/14
     GPIOA->AFR[0] = AFRf(1, 7);
@@ -57,7 +58,8 @@ static inline void gpio_setup(){
     GPIOA->MODER = MODER_AI(0)  | MODER_AI(1)  | MODER_AI(2)  | MODER_AI(3)  | MODER_I(4)   | MODER_O(5)   |
                    MODER_O(6)   | MODER_AF(7)  | MODER_I(8)   | MODER_AF(9)  | MODER_AF(10) | MODER_AF(11) |
                    MODER_AF(12) | MODER_AF(13) | MODER_AF(14) | MODER_I(15);
-    GPIOA->OSPEEDR = OSPEED_MED(7) | OSPEED_MED(9) | OSPEED_MED(10) | OSPEED_HI(11) | OSPEED_HI(12) | OSPEED_HI(13) | OSPEED_HI(14);
+    GPIOA->OSPEEDR = OSPEED_HI(4) | OSPEED_MED(7) | OSPEED_MED(9) | OSPEED_MED(10) | OSPEED_HI(11) |
+                     OSPEED_HI(12) | OSPEED_HI(13) | OSPEED_HI(14);
     // SPI for SSI: AF5 @PB3, PB4; I2C1: AF4 @PB6, PB7; CAN: AF9 @PB8, PB9; SPI2: AF5 @PB12..PB15
     GPIOB->AFR[0] = AFRf(5, 3) | AFRf(5, 4) | AFRf(4, 6) | AFRf(4, 7);
     GPIOB->AFR[1] = AFRf(9, 8) | AFRf(9, 9) | AFRf(5, 12) | AFRf(5, 13) | AFRf(5, 14) | AFRf(5, 15);
diff --git a/F3:F303/CANbus4BTA/hardware.h b/F3:F303/CANbus4BTA/hardware.h
index a623393..c1138cf 100644
--- a/F3:F303/CANbus4BTA/hardware.h
+++ b/F3:F303/CANbus4BTA/hardware.h
@@ -20,11 +20,25 @@
 
 #include <stm32f3.h>
 
+// USB pullup
 #define USBPU_port  GPIOC
 #define USBPU_pin   (1<<15)
 #define USBPU_ON()  pin_set(USBPU_port, USBPU_pin)
 #define USBPU_OFF() pin_clear(USBPU_port, USBPU_pin)
 
+// relay
+#define RELAY_port  GPIOC
+#define RELAY_pin   (1<<14)
+#define RELAY_ON()  pin_set(RELAY_port, RELAY_pin)
+#define RELAY_OFF() pin_clear(RELAY_port, RELAY_pin)
+#define RELAY_GET() pin_read(RELAY_port, RELAY_pin)
+
+// GPIO end-switches multiplexer (addr - PB0..2, ~DEN0 - PA5, ~DEN1 - PA6) and input (PA4)
+#define ESW_GET()   (GPIOA->IDR & (1<<4) ? 0 : 1)
+#define MULADDR_set(x)  do{GPIOB->BSRR = (x&7) | (((~x)&7) << 16);}while(0)
+#define MUL_ON(x)   pin_clear(GPIOA, 1<<(5+x))
+#define MUL_OFF(x)  pin_set(GPIOA, 1<<(5+x))
+
 extern volatile uint32_t Tms;
 
 void hw_setup();
diff --git a/F3:F303/CANbus4BTA/main.c b/F3:F303/CANbus4BTA/main.c
index 4263c36..91aaeb8 100644
--- a/F3:F303/CANbus4BTA/main.c
+++ b/F3:F303/CANbus4BTA/main.c
@@ -18,6 +18,7 @@
 
 #include "can.h"
 #include "flash.h"
+#include "gpio.h"
 #include "hardware.h"
 #include "textfunctions.h"
 #include "usart.h"
@@ -57,6 +58,7 @@ int main(void){
     }
     flashstorage_init();
     hw_setup();
+    // getSwitches() and set module role & CAN ID
     CAN_setup(the_conf.CANspeed);
     USBPU_ON();
     while(1){
@@ -86,5 +88,15 @@ int main(void){
             const char *ans = run_text_cmd(inbuff);
             if(ans) USB_sendstr(ans);
         }
+        ESW_process();
+        static uint8_t oldswitches[2] = {0};
+        for(int i = 0; i < 2; ++i){
+            uint8_t new = getESW(i);
+            if(oldswitches[i] != new){
+                oldswitches[i] = new;
+                USB_sendstr("ESW changed @"); printu(Tms);
+                USB_sendstr(" to "); printuhex(new); newline();
+            }
+        }
     }
 }
diff --git a/F3:F303/CANbus4BTA/proto.h b/F3:F303/CANbus4BTA/proto.h
index 5981ff8..677c4f9 100644
--- a/F3:F303/CANbus4BTA/proto.h
+++ b/F3:F303/CANbus4BTA/proto.h
@@ -60,6 +60,10 @@ typedef enum{
     CMD_ADCMUL,     // 7 - get/set ADC multipliers 0..4
     CMD_SAVECONF,   // 8 - save configuration
     CMD_ERASESTOR,  // 9 - erase all flash storage
+    CMD_RELAY,      // 10 - switch relay ON/OFF
+    CMD_GETESW_BLK, // 11 - blocking read of ESW
+    CMD_GETESW,     // 12 - current ESW state, bounce-free
+    CMD_BOUNCE,     // 13 - get/set bounce constant (ms)
     CMD_AMOUNT      // amount of CAN commands
 } can_cmd;
 
diff --git a/F3:F303/CANbus4BTA/textfunctions.c b/F3:F303/CANbus4BTA/textfunctions.c
index aff6ac3..d1615e4 100644
--- a/F3:F303/CANbus4BTA/textfunctions.c
+++ b/F3:F303/CANbus4BTA/textfunctions.c
@@ -53,12 +53,16 @@ static const funcdescr funclist[] = {
     {"adcmul", CMD_ADCMUL, "get/set ADC multipliers 0..3 (*1000)"},
     {"adcraw", CMD_ADCRAW, "get raw ADC values of channel 0..4"},
     {"adcv", CMD_ADCV,  "get ADC voltage of channel 0..3 (*100V)"},
+    {"bounce", CMD_BOUNCE, "get/set bounce constant (ms)"},
     {"canid", CMD_CANID, "get/set CAN ID"},
     {"cansnif", -TCMD_CANSNIF, "get/change sniffer state (0 - normal, 1 - sniffer)"},
     {"canspeed", CMD_CANSPEED, "get/set CAN speed (bps)"},
     {"dumpconf", -TCMD_DUMPCONF, "dump current configuration"},
+    {"esw", CMD_GETESW, "anti-bounce read ESW of channel 0 or 1"},
+    {"eswblk", CMD_GETESW_BLK, "blocking read ESW of channel 0 or 1"},
     {"eraseflash", CMD_ERASESTOR, "erase all flash storage"},
     {"mcutemp", CMD_MCUTEMP, "get MCU temperature (*10degrC)"},
+    {"relay", CMD_RELAY, "get/set relay state (0 - off, 1 - on)"},
     {"reset", CMD_RESET, "reset MCU"},
     {"s", -TCMD_CANSEND, "send CAN message: ID 0..8 data bytes"},
     {"saveconf", CMD_SAVECONF, "save configuration"},
@@ -144,7 +148,7 @@ static errcodes cansend(const char *txt){
     uint32_t Tstart = Tms;
     while(Tms - Tstart < SEND_TIMEOUT_MS){
         if(CAN_OK == CAN_send(&canmsg)){
-            USB_sendstr("OK\n");
+            //USB_sendstr("OK\n"); - don't send OK, as after sending might be an error
             return ERR_OK;
         }
     }
diff --git a/F3:F303/CANbus4BTA/version.inc b/F3:F303/CANbus4BTA/version.inc
index c14b316..7893c4b 100644
--- a/F3:F303/CANbus4BTA/version.inc
+++ b/F3:F303/CANbus4BTA/version.inc
@@ -1,2 +1,2 @@
-#define BUILD_NUMBER "56"
+#define BUILD_NUMBER "68"
 #define BUILD_DATE "2024-01-08"