STM32F103-NUCLEO BUSCAN NEEDS TO RESET NUCLEO AFTER POWERING IT TO WORK

[JGuembe.1]

I have diferent STM32F103-NUCLEOs conected via buscan, all powered by external suply 12V (VIN pin). When I supply 12V, all NUCLEOs start working but are not able to communicate via buscan. Then I pulse black button (reset button) of NUCLEOs and it works!!! Why need to reset? Could I avoid reset step?

This is my code for one NUCLEO (the others are very similar):

/* Includes ------------------------------------------------------------------*/
#include "main.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdlib.h"
#include "stdio.h"
#include "string.h"
/* USER CODE END Includes */
 
 
/* Private variables ---------------------------------------------------------*/
CAN_HandleTypeDef hcan;
 
UART_HandleTypeDef huart2;
 
/* USER CODE BEGIN PV */
CAN_TxHeaderTypeDef txHeader;
CAN_RxHeaderTypeDef rxHeader;
CAN_FilterTypeDef canfil; //CAN Bus Filter
uint32_t TxMailbox; //CAN Bus Mail box variable
 
uint8_t canTX[8]={0,0,0,0,0,0,0,0}, canRX[8]={0}; //CAN Bus Data vars
 
uint8_t status=0;
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_CAN_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
 
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART2_UART_Init();
  MX_CAN_Init();
  /* USER CODE BEGIN 2 */
  HAL_Delay(500);
  //FILTRO CAN ADMITIMOS TODOS LOS MENSAJES
  canfil.FilterBank = 0;
  canfil.FilterMode = CAN_FILTERMODE_IDMASK;
  canfil.FilterFIFOAssignment = CAN_RX_FIFO0;
  canfil.FilterIdHigh = 0;
  canfil.FilterIdLow = 0;
  canfil.FilterMaskIdHigh = 0;
  canfil.FilterMaskIdLow = 0;
  canfil.FilterScale = CAN_FILTERSCALE_32BIT;
  canfil.FilterActivation = ENABLE;
  canfil.SlaveStartFilterBank = 14;
 
  HAL_CAN_ConfigFilter(&hcan,&canfil); //Initialize CAN Filter
  HAL_CAN_Start(&hcan);
  HAL_CAN_ActivateNotification(&hcan, CAN_IT_RX_FIFO0_MSG_PENDING);
 
  // set values to the transmit header
	txHeader.DLC=8; // 8 byte
	txHeader.IDE=CAN_ID_STD;
	txHeader.RTR=CAN_RTR_DATA;
	txHeader.StdId=0x244; //Id entre 0 y 0x7FF
	txHeader.ExtId=0x02;
	txHeader.TransmitGlobalTime=DISABLE;
 
 
	canTX[4]=1; 
	HAL_CAN_AddTxMessage(&hcan, &txHeader, canTX, &TxMailbox); // Send CAN bus msg
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	canTX[4]=status; // Command value
	HAL_CAN_AddTxMessage(&hcan, &txHeader, canTX, &TxMailbox); // Send CAN bus msg
	HAL_Delay(1000); */
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  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_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief CAN Initialization Function
  * @param None
  * @retval None
  */
static void MX_CAN_Init(void)
{
  hcan.Instance = CAN1;
  hcan.Init.Prescaler = 16;
  hcan.Init.Mode = CAN_MODE_NORMAL;
  hcan.Init.SyncJumpWidth = CAN_SJW_1TQ;
  hcan.Init.TimeSeg1 = CAN_BS1_4TQ;
  hcan.Init.TimeSeg2 = CAN_BS2_2TQ;
  hcan.Init.TimeTriggeredMode = DISABLE;
  hcan.Init.AutoBusOff = DISABLE;
  hcan.Init.AutoWakeUp = DISABLE;
  hcan.Init.AutoRetransmission = DISABLE;
  hcan.Init.ReceiveFifoLocked = DISABLE;
  hcan.Init.TransmitFifoPriority = DISABLE;
  if (HAL_CAN_Init(&hcan) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief USART2 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART2_UART_Init(void)
{
 
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  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;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
 
/* USER CODE BEGIN 4 */
void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcanx){
	HAL_CAN_GetRxMessage(hcanx, CAN_RX_FIFO0, &rxHeader, canRX); //Receive CAN bus message to canRX buffer
 
		if( canRX[3]==1){ //GET VALUE
			canTX[4]=status; // Command value
			HAL_CAN_AddTxMessage(&hcan, &txHeader, canTX, &TxMailbox); // 
		}else if(canRX[3]==2){ //SET VALUEs
			if(canRX[4]==0){
				//here some actions
			}else if(canRX[4]==1){
				// here others
			}
			status = canRX[4];
			canTX[4]=status;
			HAL_CAN_AddTxMessage(&hcan, &txHeader, canTX, &TxMailbox); // Send CAN bus msg
	}
	memset(canRX,0,8);
}
/* USER CODE END 4 */
 

[Tesla DeLorean]

Instrument the code paths and error handlers so you can understand the specific flow and failure in the first case.​