bluetooth communication problem when working with two UARTs

[MaciejG]

Hi during development of program I found weird behaviour. I am using STM32G030C8T6 MCU. I am trying to connect external device using HC-05 bluetooth module. In my project I also connect with devices using MAX3485 module for RS485 communication. I wrote python app on laptop to send information to my MCU. Information is interpreted in MCU and then it answers with same information to external device to ensure correctness of communication. Everything worked well until I started to listening for response from RS485 devices. Somehow request for connection and then first request from laptop, before sending any data to RS485 devices, works as desired, but after that any data obtained from MCU is seen on laptop as 0x0b in hexadecimal. I only send one byte of information in bluetooth communication. First I thought that maybe there is a problem with priority of interrupts but then I changed NVIC settings for UARTs in .ioc file for 1 for RS485 and 0 for bluetooth and nothing changed. Also weird is that everytime i debug python script data acquired by laptop is equal to 0x0b. In case of some interferation on transmit lines it should be some random data I guess. 

Thank you in advance for any time spent on this issue

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <math.h>
/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;
UART_HandleTypeDef huart2;

/* USER CODE BEGIN PV */
//values to count servo positions
uint8_t PTS_NUM = 45;
uint8_t ZERO_SERVO = 150;
uint8_t MODULES_AMOUNT = 9;
uint8_t HOR_MAX_VAL = 180;
uint8_t VER_MAX_VAL = 166;
double HOR_PERIOD = 2 * M_PI;
double VER_PERIOD = 4 * M_PI;
double HOR_OFFSET = 0;
double VER_OFFSET = (-1.0/2.0) * M_PI;
//data buffers for communication
uint8_t RX_DATA[4];
uint8_t TX_DATA[4];
uint8_t BLU_BUFF;
uint8_t CALIBRATE_ID = 20;
//enumerators defining state and errors in robot
typedef enum {
	NO_ERROR = 0,
	CRC_ERROR = 1,
	TIMEOUT_ERROR = 2
} error_code;

typedef enum {
	STOPPED = 0,
	MOVING = 1,
	CALIBRATE = 2
} robot_state;

uint8_t ERROR_VAL = NO_ERROR;
uint8_t state = STOPPED;
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);
static void MX_USART2_UART_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void sendData(const uint8_t *data)
{
	HAL_GPIO_WritePin(TX_EN_GPIO_Port,TX_EN_Pin, GPIO_PIN_SET);
	HAL_UART_Transmit(&huart1, data, 4, 1000);
	HAL_GPIO_WritePin(TX_EN_GPIO_Port,TX_EN_Pin, GPIO_PIN_RESET);
}

void sendBluetooth(const uint8_t *data)
{
	HAL_UART_Transmit(&huart2, data, 1, 1000);
}

void handle_bluetooth(const uint8_t *data)
{
	switch (*data)
	{
	case 2:
		sendBluetooth(data);
		state=MOVING;
		break;
	case 3:
		sendBluetooth(data);
		state=CALIBRATE;
		break;
	case 4:
		sendBluetooth(data);
		state=STOPPED;
		break;
	case 5:
		state=STOPPED;
		break;
	default:
		sendBluetooth(data);
		break;
	}
}

void check_crc(const uint8_t *rx_buff, const uint8_t *tx_buff)
{
	if (rx_buff[3] != tx_buff[3])
	{
		uint8_t err;
		ERROR_VAL = CRC_ERROR;
		err = ERROR_VAL * 10 + tx_buff[0];
		sendBluetooth(&err);
	}
}

void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{
	if (huart->Instance==USART2)
	{
		handle_bluetooth(&BLU_BUFF);
		HAL_UARTEx_ReceiveToIdle_IT(huart, &BLU_BUFF, 1);
	}
	else if (huart->Instance==USART1)
	{
		check_crc(RX_DATA, TX_DATA);
		HAL_UARTEx_ReceiveToIdle_IT(huart, RX_DATA, 4);
	}
}



uint8_t crc8(uint8_t *buffer, uint8_t buff_len)
{
	uint8_t crc = 0xFF;
	while (buff_len--)
	{
		crc = crc ^ (*buffer++);
	}
	return crc;
}

//return 1 if there is no error in calc and 0 if there is

void preparePackets(uint8_t *buffer, const uint8_t slave_id, const uint8_t servo_hor, const uint8_t servo_ver)
{
	buffer[0] = slave_id;
	buffer[1] = servo_hor;
	buffer[2] = servo_ver;
	buffer[3] = crc8(buffer, 3);
}

uint8_t map(double sin_val, const uint8_t max_val)
{
	double multiplier = max_val - ZERO_SERVO;
	uint8_t mapped_val = sin_val * multiplier + ZERO_SERVO;
	return mapped_val;
}

void init_sin_values(uint8_t* sin_arr, const uint8_t max_val, const double period, const double offset)
{
	double alfa = period / (double)PTS_NUM;
	double curr_sin;
	for (int i = 0; i < PTS_NUM; i++)
	{
		curr_sin = sin(offset + i * alfa);
		*sin_arr++ = map(curr_sin, max_val);
	}
}
/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */
  HAL_Delay(100);
  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART1_UART_Init();
  MX_USART2_UART_Init();
  /* USER CODE BEGIN 2 */
  HAL_UARTEx_ReceiveToIdle_IT(&huart2, &BLU_BUFF, 1);
  HAL_UARTEx_ReceiveToIdle_IT(&huart1, RX_DATA, 4);
  uint8_t count_modules = 1;
  uint8_t current_point = 0;
  uint8_t SinArrHor[PTS_NUM];
  uint8_t SinArrVer[PTS_NUM];
  init_sin_values(SinArrHor, HOR_MAX_VAL, HOR_PERIOD, HOR_OFFSET);
  init_sin_values(SinArrVer, VER_MAX_VAL, VER_PERIOD, VER_OFFSET);
  uint8_t index_module = 0;
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */

	  for (; count_modules <= MODULES_AMOUNT && state==MOVING; count_modules++)
	  {
		  index_module = ((PTS_NUM/MODULES_AMOUNT) * (count_modules - 1) + current_point) % PTS_NUM;
		  preparePackets(TX_DATA, count_modules, SinArrHor[index_module], SinArrVer[index_module]);
		  sendData(TX_DATA);
	  	  HAL_Delay(2);
	  }
	  if (state==MOVING)
	  {
		  current_point++;
		  current_point = current_point % PTS_NUM;
		  if (count_modules > MODULES_AMOUNT)
			  count_modules = 1;
  	  }
	  else if (state==CALIBRATE)
	  {
		  preparePackets(TX_DATA, CALIBRATE_ID, 150, 150);
		  sendData(TX_DATA);
		  count_modules = 0;
		  current_point = 0;
		  state=STOPPED;
	  }
	  else if (state==STOPPED)
	  {
		  continue;
	  }
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief USART1 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_USART1_UART_Init(void)
{

  /* USER CODE BEGIN USART1_Init 0 */

  /* USER CODE END USART1_Init 0 */

  /* USER CODE BEGIN USART1_Init 1 */

  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart1.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */

  /* USER CODE END USART1_Init 2 */

}

/**
  * @brief USART2 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_USART2_UART_Init(void)
{

  /* USER CODE BEGIN USART2_Init 0 */

  /* USER CODE END USART2_Init 0 */

  /* USER CODE BEGIN USART2_Init 1 */

  /* USER CODE END USART2_Init 1 */
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 9600;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART2_Init 2 */

  /* USER CODE END USART2_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOC_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(TX_EN_GPIO_Port, TX_EN_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : TX_EN_Pin */
  GPIO_InitStruct.Pin = TX_EN_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(TX_EN_GPIO_Port, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

[Andrew Neil]

Please use this button to properly post source code - not as images:

[MaciejG]

Sorry for that, I changed it as fast as i could

[MaciejG · Accepted solution]

The problem was with the programme logic itself, after a break with a cold mind I figured it out. I did not answer from the slave module via RS485 which caused crc8 function to generate error code which in next step was sent to external PC.