diff --git a/system/include/drivers/ms5611.h b/system/include/drivers/ms5611.h
index a14cdf1..d728a30 100644
--- a/system/include/drivers/ms5611.h
+++ b/system/include/drivers/ms5611.h
@@ -30,7 +30,7 @@ typedef enum ms5611_qf {
 
 int32_t ms5611_reset(ms5611_qf_t *qf);
 int32_t ms5611_read_calibration(int32_t* cal_data, ms5611_qf_t* qf);
-unsigned char crc4(int n_prom[]);
+unsigned char crc4(int32_t* n_prom);
 int32_t ms5611_trigger_measure(int param_to_meas, int32_t* out);
 int32_t ms5611_get_temperature(float* out, ms5611_qf_t* qf);
 int32_t ms5611_get_pressure(float* out, ms5611_qf_t *qf);
diff --git a/system/src/aprs/beacon.c b/system/src/aprs/beacon.c
index feadeed..a248117 100644
--- a/system/src/aprs/beacon.c
+++ b/system/src/aprs/beacon.c
@@ -24,7 +24,7 @@ void beacon_send_own(void) {
 }
 
 void beacon_send_on_startup(void) {
-	main_own_aprs_msg_len = sprintf(main_own_aprs_msg, "> START boot_cnt %#.2x hf_cnt %#.2x hf_pc %#.8x hf_lr %#.8x", rte_main_boot_cycles, rte_main_hard_faults, rte_main_hardfault_pc, rte_main_hardfault_lr);
+	main_own_aprs_msg_len = sprintf(main_own_aprs_msg, "> START boot_cnt %#.2x hf_cnt %#.2x", (uint16_t)rte_main_boot_cycles, (uint16_t)rte_main_hard_faults);
 	main_own_aprs_msg[main_own_aprs_msg_len] = 0;
  	ax25_sendVia(&main_ax25, main_own_path, main_own_path_ln, main_own_aprs_msg, main_own_aprs_msg_len);
 	after_tx_lock = 1;
diff --git a/system/src/drivers/ms5611.c b/system/src/drivers/ms5611.c
index 54cb63a..ada67db 100644
--- a/system/src/drivers/ms5611.c
+++ b/system/src/drivers/ms5611.c
@@ -72,7 +72,6 @@ int32_t ms5611_read_calibration(int32_t* cal_data, ms5611_qf_t *out) {
 
 	int i,j;
 	int txbuf[2];	
-	int rxbuf[] = {0x00, 0x00};
 	j = 0;
 
 	// Reading calibration constants one after another. Each constant is uint16_t, so a loop iterator
@@ -132,7 +131,6 @@ int32_t ms5611_read_calibration(int32_t* cal_data, ms5611_qf_t *out) {
 // This is main function to trigger and receive raw value of measuremenets
 int32_t ms5611_trigger_measure(int param_to_meas, int32_t* out) {
 	int txbuf[] = { 0x00, 0x00};
-	long int output;
 
 	if (ms5611_sensor_avaliable == 0) {
 		return MS5611_SENSOR_NOT_AVALIABLE;
@@ -331,35 +329,35 @@ int32_t ms5611_get_pressure(float* out, ms5611_qf_t *qf) {
 
 }
 
-// funkcja obliczaj�ca sum� kontroln� CRC4 z wsp�czynnik�w kalibracyjncyh
-unsigned char crc4(int n_prom[])
+
+unsigned char crc4(int32_t* n_prom)
 {
-int cnt; // simple counter
-unsigned int n_rem; // crc reminder
-unsigned int crc_read; // original value of the crc
-unsigned char n_bit;
-n_rem = 0x00;
-crc_read=n_prom[7]; //save read CRC
-n_prom[7]=(0xFF00 & (n_prom[7])); //CRC byte is replaced by 0
-for (cnt = 0; cnt < 16; cnt++) // operation is performed on bytes
-{// choose LSB or MSB
-if (cnt%2==1) n_rem ^= (unsigned short) ((n_prom[cnt>>1]) & 0x00FF);
-else n_rem ^= (unsigned short) (n_prom[cnt>>1]>>8);
-for (n_bit = 8; n_bit > 0; n_bit--)
-{
-if (n_rem & (0x8000))
-{
-n_rem = (n_rem << 1) ^ 0x3000;
-}
-else
-{
-n_rem = (n_rem << 1);
-}
-}
-}
-n_rem= (0x000F & (n_rem >> 12)); // final 4-bit reminder is CRC code
-n_prom[7]=crc_read; // restore the crc_read to its original place
-return (n_rem ^ 0x0);
+	int cnt; // simple counter
+	unsigned int n_rem; // crc reminder
+	unsigned int crc_read; // original value of the crc
+	unsigned char n_bit;
+	n_rem = 0x00;
+	crc_read=n_prom[7]; //save read CRC
+	n_prom[7]=(0xFF00 & (n_prom[7])); //CRC byte is replaced by 0
+	for (cnt = 0; cnt < 16; cnt++) // operation is performed on bytes
+	{// choose LSB or MSB
+		if (cnt%2 == 1) n_rem ^= (unsigned short) ((n_prom[cnt>>1]) & 0x00FF);
+		else n_rem ^= (unsigned short) (n_prom[cnt>>1]>>8);
+		for (n_bit = 8; n_bit > 0; n_bit--)
+		{
+			if (n_rem & (0x8000))
+			{
+				n_rem = (n_rem << 1) ^ 0x3000;
+			}
+			else
+			{
+				n_rem = (n_rem << 1);
+			}
+		}
+	}
+	n_rem= (0x000F & (n_rem >> 12)); // final 4-bit reminder is CRC code
+	n_prom[7]=crc_read; // restore the crc_read to its original place
+	return (n_rem ^ 0x0);
 }
 
 
diff --git a/system/src/drivers/serial.c b/system/src/drivers/serial.c
index f9cce15..7641adb 100644
--- a/system/src/drivers/serial.c
+++ b/system/src/drivers/serial.c
@@ -650,10 +650,11 @@ void srl_irq_handler(srl_context_t *ctx) {
 		switch (ctx->srl_tx_state) {
 		case SRL_TXING:
 			if (ctx->srl_tx_bytes_counter < ctx->srl_tx_bytes_req) {
-				if (ctx->te_port != 0)
+				if (ctx->te_port != 0) {
 					GPIO_SetBits(ctx->te_port, ctx->te_pin);
+				}
 
-					ctx->port->DR = ctx->srl_tx_buf_pointer[ctx->srl_tx_bytes_counter++];
+				ctx->port->DR = ctx->srl_tx_buf_pointer[ctx->srl_tx_bytes_counter++];
 			}
 			else {
 				while((ctx->port->SR & USART_SR_TC) != USART_SR_TC);
diff --git a/system/src/umb_master/umb_master.c b/system/src/umb_master/umb_master.c
index d951f52..1da405c 100644
--- a/system/src/umb_master/umb_master.c
+++ b/system/src/umb_master/umb_master.c
@@ -61,7 +61,6 @@ void umb_master_init(umb_context_t* ctx, srl_context_t* serial_ctx, const config
 umb_retval_t umb_parse_serial_buffer_to_frame(uint8_t* serial_buffer, uint16_t buffer_ln, umb_frame_t* frame) {
 
 	uint16_t crc = 0xFFFFu;
-	uint16_t crc_from_frame;
 
 	if (serial_buffer[0] != SOH && serial_buffer[1] != V10)
 		return UMB_NOT_VALID_FRAME;
@@ -88,9 +87,6 @@ umb_retval_t umb_parse_serial_buffer_to_frame(uint8_t* serial_buffer, uint16_t b
 		frame->payload[i] = serial_buffer[10 + i];
 	}
 
-	// Retrieving the crc value from frame
-	crc_from_frame = serial_buffer[frame->lenght + 9] | (serial_buffer[frame->lenght + 10] << 8);
-
 	// recalculating crc from frame content
 	for (int j = 0; j <= frame->lenght + 8 + 2; j++) {
 		crc = umb_calc_crc(crc, serial_buffer[j]);