Question
Two STM32F4-discovery boards unable to communicate over CAN
Hi,
I am new to HAL libraries and currently working on a small CAN bus consisting of two STM32F4-discovery boards connected to a CAN transceiver connected to the bus. Both transceivers are externally powered with 5V.
So far, I tried the existing CAN examples from the STM32CubeF4 github. The loopback example works fine, the normal mode example does not.
After a few transmissions the mailboxes are filled and the transmit function returns an error. And I can't figure out why it does not transmit the requests. Below you can find the code I on both discovery boards. It is basically the Networking example but with some light adjustments for LED output pins.
Any ideas on why this might not be working as expected?
#include "main.h"
#define KEY_PRESSED 0x00
#define KEY_NOT_PRESSED 0x01
uint8_t ubKeyNumber = 0x0;
CAN_HandleTypeDef CanHandle;
CAN_TxHeaderTypeDef TxHeader;
CAN_RxHeaderTypeDef RxHeader;
uint8_t TxData[8];
uint8_t RxData[8];
uint32_t TxMailbox;
void SystemClock_Config(void);
void Error_Handler(void);
void CAN_Config(void);
void LED_Display(uint8_t LedStatus);
void Init_OnBoard_LEDs(void);
int main(void)
{
HAL_Init();
/* Configure the system clock to 168 MHz */
SystemClock_Config();
/* Configure LED1, LED2, LED3 and LED4 */
Init_OnBoard_LEDs();
LED_Display(ubKeyNumber);
/* Configure the CAN peripheral */
CAN_Config();
/* Infinite loop */
while (1)
{
uint8_t state = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0);
if (state)
{
if (ubKeyNumber == 0x4)
{
ubKeyNumber = 0x00;
}
else
{
LED_Display(++ubKeyNumber);
/* Set the data to be transmitted */
TxData[0] = ubKeyNumber;
TxData[1] = 0xAD;
/* Start the Transmission process */
if (HAL_CAN_AddTxMessage(&CanHandle, &TxHeader, TxData, &TxMailbox) != HAL_OK)
{
/* Transmission request Error */
Error_Handler();
}
HAL_Delay(1000);
}
}
}
}
void Init_OnBoard_LEDs(void){
__HAL_RCC_GPIOD_CLK_ENABLE();
GPIO_InitTypeDef BoardLEDs;
BoardLEDs.Mode = GPIO_MODE_OUTPUT_PP;
BoardLEDs.Pin = GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
HAL_GPIO_Init(GPIOD, &BoardLEDs);
__HAL_RCC_GPIOA_CLK_ENABLE();
GPIO_InitTypeDef BlueButton;
BlueButton.Mode = GPIO_MODE_INPUT;
BlueButton.Pin = GPIO_PIN_0;
BlueButton.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOA, &BlueButton);
}
void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitTypeDef RCC_OscInitStruct;
/* Enable Power Control clock */
__HAL_RCC_PWR_CLK_ENABLE();
/* The voltage scaling allows optimizing the power consumption when the device is
clocked below the maximum system frequency, to update the voltage scaling value
regarding system frequency refer to product datasheet. */
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/* Enable HSE Oscillator and activate PLL with HSE as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 7;
HAL_RCC_OscConfig(&RCC_OscInitStruct);
/* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2
clocks dividers */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5);
/* STM32F405x/407x/415x/417x Revision Z devices: prefetch is supported */
if (HAL_GetREVID() == 0x1001)
{
/* Enable the Flash prefetch */
__HAL_FLASH_PREFETCH_BUFFER_ENABLE();
}
}
/**
* @brief This function is executed in case of error occurrence.
* @param None
* @retval None
*/
void Error_Handler(void)
{
while (1)
{
}
}
/**
* @brief Configures the CAN.
* @param None
* @retval None
*/
void CAN_Config(void)
{
//Tx: PB12
//Rx: PB13
CAN_FilterTypeDef sFilterConfig;
/*##-1- Configure the CAN peripheral #######################################*/
CanHandle.Instance = CAN2;
CanHandle.Init.TimeTriggeredMode = DISABLE;
CanHandle.Init.AutoBusOff = DISABLE;
CanHandle.Init.AutoWakeUp = DISABLE;
CanHandle.Init.AutoRetransmission = ENABLE;
CanHandle.Init.ReceiveFifoLocked = DISABLE;
CanHandle.Init.TransmitFifoPriority = DISABLE;
CanHandle.Init.Mode = CAN_MODE_NORMAL;
CanHandle.Init.SyncJumpWidth = CAN_SJW_1TQ;
CanHandle.Init.TimeSeg1 = CAN_BS1_4TQ;
CanHandle.Init.TimeSeg2 = CAN_BS2_2TQ;
CanHandle.Init.Prescaler = 6;
if (HAL_CAN_Init(&CanHandle) != HAL_OK)
{
/* Initialization Error */
Error_Handler();
}
/*##-2- Configure the CAN Filter ###########################################*/
sFilterConfig.FilterBank = 0;
sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
sFilterConfig.FilterIdHigh = 0x0000;
sFilterConfig.FilterIdLow = 0x0000;
sFilterConfig.FilterMaskIdHigh = 0x0000;
sFilterConfig.FilterMaskIdLow = 0x0000;
sFilterConfig.FilterFIFOAssignment = CAN_RX_FIFO0;
sFilterConfig.FilterActivation = ENABLE;
sFilterConfig.SlaveStartFilterBank = 14;
if (HAL_CAN_ConfigFilter(&CanHandle, &sFilterConfig) != HAL_OK)
{
/* Filter configuration Error */
Error_Handler();
}
/*##-3- Start the CAN peripheral ###########################################*/
if (HAL_CAN_Start(&CanHandle) != HAL_OK)
{
/* Start Error */
Error_Handler();
}
/*##-4- Activate CAN RX notification #######################################*/
if (HAL_CAN_ActivateNotification(&CanHandle, CAN_IT_RX_FIFO0_MSG_PENDING) != HAL_OK)
{
/* Notification Error */
Error_Handler();
}
/*##-5- Configure Transmission process #####################################*/
TxHeader.StdId = 0x321;
TxHeader.ExtId = 0x01;
TxHeader.RTR = CAN_RTR_DATA;
TxHeader.IDE = CAN_ID_STD;
TxHeader.DLC = 2;
TxHeader.TransmitGlobalTime = DISABLE;
}
/**
* @brief Rx Fifo 0 message pending callback
* @param hcan: pointer to a CAN_HandleTypeDef structure that contains
* the configuration information for the specified CAN.
* @retval None
*/
void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan)
{
/* Get RX message */
if (HAL_CAN_GetRxMessage(hcan, CAN_RX_FIFO0, &RxHeader, RxData) != HAL_OK)
{
/* Reception Error */
Error_Handler();
}
/* Display LEDx */
if ((RxHeader.StdId == 0x321) && (RxHeader.IDE == CAN_ID_STD) && (RxHeader.DLC == 2))
{
LED_Display(RxData[0]);
ubKeyNumber = RxData[0];
}
}
/**
* @brief Turns ON/OFF the dedicated LED.
* @param LedStatus: LED number from 0 to 3
* @retval None
*/
void LED_Display(uint8_t LedStatus)
{
/* Turn OFF all LEDs */
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12, GPIO_PIN_RESET);
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_13, GPIO_PIN_RESET);
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_14, GPIO_PIN_RESET);
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_15, GPIO_PIN_RESET);
switch(LedStatus){
case(0x0):
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12, GPIO_PIN_SET);
break;
case(0x1):
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_13, GPIO_PIN_SET);
break;
case(0x2):
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_14, GPIO_PIN_SET);
break;
case(0x3):
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_15, GPIO_PIN_SET);
break;
default:
break;
}
}