diff --git a/F3:F303/MLX90640-allsky/Readme.md b/F3:F303/MLX90640-allsky/Readme.md
index f0567ac..468e95b 100644
--- a/F3:F303/MLX90640-allsky/Readme.md
+++ b/F3:F303/MLX90640-allsky/Readme.md
@@ -7,7 +7,9 @@ thermal imaging sensors (32×24 pixels each), designed for **cloud monitoring**
 Astrophysical Observatory of the Russian Academy of Sciences. The system automates sky quality
 assessment for 0.5-meter telescopes of the "Astro-M" complex.
 
-The device continuously captures thermal images from multiple sensors (Zenith, East, South, West, North), processes environmental data from a **BMP280** pressure/humidity/temperature sensor, and controls **PWM heaters** to prevent dew formation on optics.
+The device continuously captures thermal images from multiple sensors (Zenith, East, South, West,
+North), processes environmental data from a **BMP280** pressure/humidity/temperature sensor, and
+controls **PWM heaters** to prevent dew formation on optics.
 
 **Repository:** [https://github.com/eddyem/stm32samples/tree/master/F3%3AF303/MLX90640-allsky](https://github.com/eddyem/stm32samples/tree/master/F3%3AF303/MLX90640-allsky)
 
@@ -160,7 +162,8 @@ Measurements are triggered every `ENV_MEAS_PERIOD` (10 seconds) in forced mode.
 
 ## Command Protocol
 
-The device presents a **virtual COM port** (CDC) over USB and a second UART interface. Both share the same command set.
+The device presents a **virtual COM port** (CDC) over USB and a second UART interface. Both share
+the same command set.
 
 ### Command Syntax
 ```
@@ -290,7 +293,9 @@ T_MEASUREMENT=12345678
 ### Prerequisites
 - ARM GCC toolchain (`arm-none-eabi-gcc`)
 - Make
-- [st-flash](https://github.com/texane/stlink), [stm32flash](https://sourceforge.net/projects/stm32flash/) or [OpenOCD](https://openocd.sourceforge.io) (for flashing MCU)
+- [st-flash](https://github.com/texane/stlink),
+       [stm32flash](https://sourceforge.net/projects/stm32flash/) or
+       [OpenOCD](https://openocd.sourceforge.io) (for flashing MCU)
 
 ### Build
 ```bash
diff --git a/F3:F303/MLX90640-allsky/adc.c b/F3:F303/MLX90640-allsky/adc.c
index 1dc8689..c99570e 100644
--- a/F3:F303/MLX90640-allsky/adc.c
+++ b/F3:F303/MLX90640-allsky/adc.c
@@ -46,19 +46,20 @@ TRUE_INLINE void calADC(ADC_TypeDef *chnl){
     chnl->CR = ADC_CR_ADVREGEN_0;
     // wait for 10us
     uint16_t ctr = 0;
-    while(++ctr < 1000){nop();}
+    while(++ctr < 1000){IWDG->KR = IWDG_REFRESH;}
     // ADCALDIF=0 (single channels)
     if((chnl->CR & ADC_CR_ADEN)){
         chnl->CR |= ADC_CR_ADSTP;
         chnl->CR |= ADC_CR_ADDIS;
     }
     chnl->CR |= ADC_CR_ADCAL;
-    while((chnl->CR & ADC_CR_ADCAL) != 0 && ++ctr < 0xfff0){};
+    while((chnl->CR & ADC_CR_ADCAL) != 0 && ++ctr < 0xfff0){IWDG->KR = IWDG_REFRESH;};
     chnl->CR = ADC_CR_ADVREGEN_0;
     // enable ADC
     ctr = 0;
     do{
-          chnl->CR |= ADC_CR_ADEN;
+        chnl->CR |= ADC_CR_ADEN;
+        IWDG->KR = IWDG_REFRESH;
     }while((chnl->ISR & ADC_ISR_ADRDY) == 0 && ++ctr < 0xfff0);
 }
 
@@ -80,14 +81,16 @@ void adc_setup(){
     ADC12_COMMON->CCR = ADC_CCR_TSEN | ADC_CCR_VREFEN | ADC_CCR_CKMODE; // enable Tsens and Vref, HCLK/4
     calADC(ADC1);
     calADC(ADC2);
-    // ADC1: channels 1,2,3,4,16,18
-    ADC1->SMPR1 = ADC_SMPR1_SMP0 | ADC_SMPR1_SMP1 | ADC_SMPR1_SMP2 | ADC_SMPR1_SMP3;
-    ADC1->SMPR2 = ADC_SMPR2_SMP15 | ADC_SMPR2_SMP17;
+    // ADC1: channels 1,2,3,4,16,18; 601.5 clock cycles
+    //ADC1->SMPR1 = ADC_SMPR1_SMP0 | ADC_SMPR1_SMP1 | ADC_SMPR1_SMP2 | ADC_SMPR1_SMP3;
+    ADC1->SMPR1 = ADC_SMPR1_SMP1 | ADC_SMPR1_SMP2 | ADC_SMPR1_SMP3 | ADC_SMPR1_SMP4;
+    //ADC1->SMPR2 = ADC_SMPR2_SMP15 | ADC_SMPR2_SMP17;
+    ADC1->SMPR2 = ADC_SMPR2_SMP16 | ADC_SMPR2_SMP18;
     // 6 conversions in group: 1->2->3->4->16->18
     ADC1->SQR1 = (1<<6) | (2<<12) | (3<<18) | (4<<24) | (NUMBER_OF_ADC1_CHANNELS-1);
     ADC1->SQR2 = (16<<0) | (18<<6);
     // ADC2: channel 2
-    ADC2->SMPR1 = ADC_SMPR1_SMP1;
+    ADC2->SMPR1 = ADC_SMPR1_SMP2;
     ADC2->SQR1 = (2<<6) | (NUMBER_OF_ADC2_CHANNELS-1);
     // configure DMA for ADC
     RCC->AHBENR |= RCC_AHBENR_DMA1EN | RCC_AHBENR_DMA2EN;
@@ -122,12 +125,12 @@ void adc_setup(){
  */
 uint16_t getADCval(uint8_t nch){
     if(nch >= NUMBER_OF_ADC_CHANNELS) return 0;
-    register uint16_t temp;
+    uint16_t temp;
 #define PIX_SORT(a,b) { if ((a)>(b)) PIX_SWAP((a),(b)); }
 #define PIX_SWAP(a,b) { temp=(a);(a)=(b);(b)=temp; }
     uint16_t p[9];
     int adval = (nch >= NUMBER_OF_ADC1_CHANNELS) ? NUMBER_OF_ADC2_CHANNELS : NUMBER_OF_ADC1_CHANNELS;
-    int addr = (nch >= NUMBER_OF_ADC1_CHANNELS) ? nch - NUMBER_OF_ADC2_CHANNELS + ADC2START: nch;
+    int addr = (nch >= NUMBER_OF_ADC1_CHANNELS) ? nch - NUMBER_OF_ADC1_CHANNELS + ADC2START: nch;
     for(int i = 0; i < 9; ++i, addr += adval) // first we should prepare array for optmed
         p[i] = ADC_array[addr];
     PIX_SORT(p[1], p[2]) ; PIX_SORT(p[4], p[5]) ; PIX_SORT(p[7], p[8]) ;
diff --git a/F3:F303/MLX90640-allsky/allsky.bin b/F3:F303/MLX90640-allsky/allsky.bin
index 202c9a8..b3e42d7 100755
Binary files a/F3:F303/MLX90640-allsky/allsky.bin and b/F3:F303/MLX90640-allsky/allsky.bin differ
diff --git a/F3:F303/MLX90640-allsky/commproto.cpp b/F3:F303/MLX90640-allsky/commproto.cpp
index 32e7326..8e80f04 100644
--- a/F3:F303/MLX90640-allsky/commproto.cpp
+++ b/F3:F303/MLX90640-allsky/commproto.cpp
@@ -595,9 +595,8 @@ static constexpr uint32_t hash(const char* str, uint32_t h = 0) {
     return *str ? hash(str + 1, h + ((h << 7) ^ *str)) : h;
 }
 
-
-const char *parse_cmd(int (*sendfun)(const char*), char *buf) {
-    if(!buf || !*buf || !sendfun) return NULL;
+// set temporary sender
+void set_sender(sendfun_t sendfun){
     SEND = sendfun;
     if(sendfun == usb_sender){
         putb = usb_putb;
@@ -606,6 +605,15 @@ const char *parse_cmd(int (*sendfun)(const char*), char *buf) {
         putb = usart_putb;
         sendbin = usart_sendbin;
     }
+}
+
+sendfun_t get_sender(){
+    return SEND;
+}
+
+const char *parse_cmd(sendfun_t sendfun, char *buf) {
+    if(!buf || !*buf || !sendfun) return NULL;
+    set_sender(sendfun);
     char command[CMD_MAXLEN+1];
     int i = 0;
     while(*buf > '@' && i < CMD_MAXLEN) command[i++] = *buf++;
diff --git a/F3:F303/MLX90640-allsky/commproto.h b/F3:F303/MLX90640-allsky/commproto.h
index fc4d7ee..d68cbbc 100644
--- a/F3:F303/MLX90640-allsky/commproto.h
+++ b/F3:F303/MLX90640-allsky/commproto.h
@@ -49,10 +49,14 @@ typedef enum{
 // maximal available parameter number (for 16-bit registers is 0xffff
 #define MAXPARNO    0xffff
 
+typedef int (*sendfun_t)(const char*);
+
 extern const char *EQ;
-const char *parse_cmd(int (*sendfun)(const char*), char *buf);
+const char *parse_cmd(sendfun_t sendfun, char *buf);
 void set_senders(int (*usbs)(const char*), int (*usbb)(uint8_t), int (*usbbin)(const uint8_t*, int),
                  int (*usarts)(const char*), int (*usartb)(uint8_t),  int (*usartbin)(const uint8_t*, int));
+void set_sender(sendfun_t sendfun);
+sendfun_t get_sender();
 
 extern const char *const Timage;
 
diff --git a/F3:F303/MLX90640-allsky/i2c.c b/F3:F303/MLX90640-allsky/i2c.c
index a6e822b..62bf3a4 100644
--- a/F3:F303/MLX90640-allsky/i2c.c
+++ b/F3:F303/MLX90640-allsky/i2c.c
@@ -116,6 +116,8 @@ void i2c_setup(i2c_speed_t speed){
     RCC->AHBENR |= RCC_AHBENR_DMA1EN;
     NVIC_EnableIRQ(DMA1_Channel6_IRQn);
     NVIC_EnableIRQ(DMA1_Channel7_IRQn);
+    NVIC_SetPriority(DMA1_Channel6_IRQn, 3);
+    NVIC_SetPriority(DMA1_Channel7_IRQn, 3);
     I2Cbusy = 0;
     i2c_curspeed = speed;
 }
@@ -153,7 +155,7 @@ static uint8_t waitISRbit(uint32_t bit, uint8_t isset){
     }
     return 1;
 goterr:
-    I2C1->ICR = 0xff;
+    I2C1->ICR = 0x3f38; // clear all errors
     return 0;
 }
 
diff --git a/F3:F303/MLX90640-allsky/ir-allsky.creator.user b/F3:F303/MLX90640-allsky/ir-allsky.creator.user
index 4dd6952..288daa7 100644
--- a/F3:F303/MLX90640-allsky/ir-allsky.creator.user
+++ b/F3:F303/MLX90640-allsky/ir-allsky.creator.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 19.0.2, 2026-05-29T11:48:44. -->
+<!-- Written by QtCreator 19.0.2, 2026-06-01T09:34:42. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>
diff --git a/F3:F303/MLX90640-allsky/main.c b/F3:F303/MLX90640-allsky/main.c
index 4e6495a..7674096 100644
--- a/F3:F303/MLX90640-allsky/main.c
+++ b/F3:F303/MLX90640-allsky/main.c
@@ -83,16 +83,19 @@ int main(void){
                 usart_sendstr(foundid); usart_sendstr(straddr); usart_putbyte('\n');
             }
         }
+        IWDG->KR = IWDG_REFRESH;
         mlx_process();
-        if(cartoon) for(int i = 0; i < N_SENSORS; ++i){ // USB-only
+        if(cartoon && CDCready) for(int i = 0; i < N_SENSORS; ++i){ // USB-only
             uint32_t Tnow = mlx_lastimT(i);
             if(Tnow != Tlastima[i]){
                 fp_t *im = mlx_getimage(i);
                 if(im){
-                    //U(Sensno); UN(i2str(i));
+                    sendfun_t cursender = get_sender();
+                    set_sender(USB_sendstr);
                     U(Timage); USB_putbyte('0'+i); USB_putbyte('='); UN(u2str(Tnow));
                     drawIma(im);
                     Tlastima[i] = Tnow;
+                    set_sender(cursender);
                 }
             }
         }
diff --git a/F3:F303/MLX90640-allsky/mlx90640.c b/F3:F303/MLX90640-allsky/mlx90640.c
index 73b3a76..c546eb6 100644
--- a/F3:F303/MLX90640-allsky/mlx90640.c
+++ b/F3:F303/MLX90640-allsky/mlx90640.c
@@ -43,7 +43,7 @@ static void occacc(int8_t *arr, int l, const uint16_t *regstart){
     int n = l >> 2; // divide by 4
     int8_t *p = arr;
     for(int i = 0; i < n; ++i){
-        register uint16_t val = *regstart++;
+        uint16_t val = *regstart++;
         *p++ = (val & 0x000F) >> 0;
         *p++ = (val & 0x00F0) >> 4;
         *p++ = (val & 0x0F00) >> 8;
@@ -123,7 +123,7 @@ MLX90640_params *get_parameters(const uint16_t dataarray[MLX_DMA_MAXLEN]){
         int idx = (row&1)<<1;
         for(int col = 0; col < MLX_W; ++col){
             // offset
-            register uint16_t rv = *pu16++;
+            uint16_t rv = *pu16++;
             i16 = (rv & 0xFC00) >> 10;
             if(i16 > 0x1F) i16 -= 0x40;
             *offset++ = (fp_t)offavg + (fp_t)occRow[row]*occRowScale + (fp_t)occColumn[col]*occColumnScale + (fp_t)i16*occRemScale;
diff --git a/F3:F303/MLX90640-allsky/strfunc.c b/F3:F303/MLX90640-allsky/strfunc.c
index 4d0009e..a9c086c 100644
--- a/F3:F303/MLX90640-allsky/strfunc.c
+++ b/F3:F303/MLX90640-allsky/strfunc.c
@@ -23,7 +23,7 @@
 // hex line number for hexdumps
 void u16s(uint16_t n, char *buf){
     for(int j = 3; j > -1; --j){
-        register uint8_t q = n & 0xf;
+        uint8_t q = n & 0xf;
         n >>= 4;
         if(q < 10) buf[j] = q + '0';
         else buf[j] = q - 10 + 'a';
@@ -40,7 +40,7 @@ void hexdump(int (*sendfun)(const char *s), uint8_t *arr, uint16_t len){
     char buf[64] = "0000  ", *bptr = &buf[6];
     for(uint16_t l = 0; l < len; ++l, ++arr){
         for(int16_t j = 1; j > -1; --j){
-            register uint8_t half = (*arr >> (4*j)) & 0x0f;
+            uint8_t half = (*arr >> (4*j)) & 0x0f;
             if(half < 10) *bptr++ = half + '0';
             else *bptr++ = half - 10 + 'a';
         }
@@ -66,7 +66,7 @@ void hexdump16(int (*sendfun)(const char *s), uint16_t *arr, uint16_t len){
         //uint16_t val = *arr;
         u16s(*arr, bptr);
         /*for(int16_t j = 3; j > -1; --j){
-            register uint8_t q = val & 0xf;
+            uint8_t q = val & 0xf;
             val >>= 4;
             if(q < 10) bptr[j] = q + '0';
             else bptr[j] = q - 10 + 'a';
@@ -297,8 +297,8 @@ const char *getint(const char *txt, int32_t *I){
     int32_t sign = 1;
     uint32_t U;
     if(*s == '-'){
-    	sign = -1;
-    	++s;
+        sign = -1;
+        ++s;
     }
     const char *nxt = getnum(s, &U);
     if(nxt == s) return txt;
@@ -341,7 +341,7 @@ char *float2str(float x, uint8_t prec){
         uint8_t m = 0;
         if(pow < 0){pow = -pow; m = 1;}
         while(pow){
-            register int p10 = pow/10;
+            int p10 = pow/10;
             *s-- = '0' + (pow - 10*p10);
             pow = p10;
         }
@@ -355,7 +355,7 @@ char *float2str(float x, uint8_t prec){
         uint32_t decimals = (uint32_t)((x-units+rounds[prec])*pwr10[prec]);
         // print decimals
         while(prec){
-            register int d10 = decimals / 10;
+            int d10 = decimals / 10;
             *s-- = '0' + (decimals - 10*d10);
             decimals = d10;
             --prec;
@@ -368,7 +368,7 @@ char *float2str(float x, uint8_t prec){
     // print main units
     if(units == 0) *s-- = '0';
     else while(units){
-        register uint32_t u10 = units / 10;
+        uint32_t u10 = units / 10;
         *s-- = '0' + (units - 10*u10);
         units = u10;
     }
diff --git a/F3:F303/MLX90640-allsky/usart.c b/F3:F303/MLX90640-allsky/usart.c
index 8e766e0..2b64bab 100644
--- a/F3:F303/MLX90640-allsky/usart.c
+++ b/F3:F303/MLX90640-allsky/usart.c
@@ -149,8 +149,9 @@ int usart_setup(uint32_t speed){
     NVIC_EnableIRQ(USART1_IRQn);
     NVIC_EnableIRQ(DMA1_Channel4_IRQn);
     NVIC_EnableIRQ(DMA1_Channel5_IRQn);
-    NVIC_SetPriority(DMA1_Channel5_IRQn, 0);
-    NVIC_SetPriority(USART1_IRQn, 4); // set character match priority lower
+    NVIC_SetPriority(DMA1_Channel4_IRQn, 4);
+    NVIC_SetPriority(DMA1_Channel5_IRQn, 4);
+    NVIC_SetPriority(USART1_IRQn, 5); // set character match priority lower
     return TRUE;
 }
 
@@ -162,7 +163,7 @@ void usart_stop(){
 void usart1_exti25_isr(){
     DMA1_Channel5->CCR &= ~DMA_CCR_EN; // temporaly disable DMA
     USART1->ICR = USART_ICR_CMCF; // clear character match flag
-    register int l = UARTBUFSZI - DMA1_Channel5->CNDTR - 1; // substitute '\n' with '\0', omit empty strings!
+    int l = UARTBUFSZI - DMA1_Channel5->CNDTR - 1; // substitute '\n' with '\0', omit empty strings!
     if(l > 0){
         if(recvdatalen){ // user didn't read old data - mark as buffer overflow
             bufovr = 1;
diff --git a/F3:F303/MLX90640-allsky/version.inc b/F3:F303/MLX90640-allsky/version.inc
index 80b70ea..6bc5225 100644
--- a/F3:F303/MLX90640-allsky/version.inc
+++ b/F3:F303/MLX90640-allsky/version.inc
@@ -1,2 +1,2 @@
-#define BUILD_NUMBER "67"
-#define BUILD_DATE "2026-05-29"
+#define BUILD_NUMBER "68"
+#define BUILD_DATE "2026-06-01"