I'm trying to set up CAN in the Nucleo STM32H723 eval kit, I can see the message written to the CAN RAM, but I dont see any activity on the TX pin using an oscilloscope. The CAN is configured in NORMAL_MODE, I have testes before with EXTERNAL_LOOPBACK and I can receive messages on the same board, but I want to transmit it to the bus.
For now I only have the TX and RX pins, PD1 and PD0, respectively, they aren't connected to anything, not even a transceiver, nor terminating resistors but I assume I should still see something in the TX pin when I'm transmitting.
The code is the following:
/* Includes ------------------------------------------------------------------*/
#include "main.h"
FDCAN_HandleTypeDef hfdcan1;
// FDCAN1 Defines
FDCAN_TxHeaderTypeDef TxHeader1;
FDCAN_RxHeaderTypeDef RxHeader1;
uint8_t TxData1[8] = {
85,85,85,85,
85,85,85,85
};
uint8_t RxData1[8];
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
// Configure TX Header for FDCAN1
TxHeader1.Identifier = 0x55;
TxHeader1.IdType = FDCAN_STANDARD_ID;
TxHeader1.TxFrameType = FDCAN_DATA_FRAME;
TxHeader1.DataLength = FDCAN_DLC_BYTES_8;
TxHeader1.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
TxHeader1.BitRateSwitch = FDCAN_BRS_OFF;
TxHeader1.FDFormat = FDCAN_FD_CAN;
TxHeader1.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
TxHeader1.MessageMarker = 0;
/* 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 */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_FDCAN1_Init();
/* USER CODE BEGIN 2 */
if(HAL_FDCAN_Start(&hfdcan1)!= HAL_OK)
{
Error_Handler();
}
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
if (HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan1, &TxHeader1, TxData1)!= HAL_OK)
{
Error_Handler();
}
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};
/** Supply configuration update enable
*/
HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
/** Configure the main internal regulator output voltage
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);
while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
/** 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_BYPASS;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 4;
RCC_OscInitStruct.PLL.PLLN = 275;
RCC_OscInitStruct.PLL.PLLP = 1;
RCC_OscInitStruct.PLL.PLLQ = 4;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_1;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLFRACN = 0;
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_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_3) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief FDCAN1 Initialization Function
* @PAram None
* @retval None
*/
static void MX_FDCAN1_Init(void)
{
/* USER CODE BEGIN FDCAN1_Init 0 */
/* USER CODE END FDCAN1_Init 0 */
/* USER CODE BEGIN FDCAN1_Init 1 */
/* USER CODE END FDCAN1_Init 1 */
hfdcan1.Instance = FDCAN1;
hfdcan1.Init.FrameFormat = FDCAN_FRAME_CLASSIC;
hfdcan1.Init.Mode = FDCAN_MODE_NORMAL;
hfdcan1.Init.AutoRetransmission = DISABLE;
hfdcan1.Init.TransmitPause = DISABLE;
hfdcan1.Init.ProtocolException = DISABLE;
hfdcan1.Init.NominalPrescaler = 11;
hfdcan1.Init.NominalSyncJumpWidth = 1;
hfdcan1.Init.NominalTimeSeg1 = 17;
hfdcan1.Init.NominalTimeSeg2 = 7;
hfdcan1.Init.DataPrescaler = 25;
hfdcan1.Init.DataSyncJumpWidth = 1;
hfdcan1.Init.DataTimeSeg1 = 5;
hfdcan1.Init.DataTimeSeg2 = 3;
hfdcan1.Init.MessageRAMOffset = 0;
hfdcan1.Init.StdFiltersNbr = 0;
hfdcan1.Init.ExtFiltersNbr = 0;
hfdcan1.Init.RxFifo0ElmtsNbr = 1;
hfdcan1.Init.RxFifo0ElmtSize = FDCAN_DATA_BYTES_8;
hfdcan1.Init.RxFifo1ElmtsNbr = 0;
hfdcan1.Init.RxFifo1ElmtSize = FDCAN_DATA_BYTES_8;
hfdcan1.Init.RxBuffersNbr = 0;
hfdcan1.Init.RxBufferSize = FDCAN_DATA_BYTES_8;
hfdcan1.Init.TxEventsNbr = 0;
hfdcan1.Init.TxBuffersNbr = 0;
hfdcan1.Init.TxFifoQueueElmtsNbr = 1;
hfdcan1.Init.TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;
hfdcan1.Init.TxElmtSize = FDCAN_DATA_BYTES_8;
if (HAL_FDCAN_Init(&hfdcan1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN FDCAN1_Init 2 */
/* USER CODE END FDCAN1_Init 2 */
}
and HAL_FDCAN_Init itself calls, which configures the TX and RX pins, PD1 and PD0 respectively.
void HAL_FDCAN_MspInit(FDCAN_HandleTypeDef* hfdcan)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
if(hfdcan->Instance==FDCAN1)
{
/* USER CODE BEGIN FDCAN1_MspInit 0 */
/* USER CODE END FDCAN1_MspInit 0 */
/** Initializes the peripherals clock
*/
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_FDCAN;
PeriphClkInitStruct.FdcanClockSelection = RCC_FDCANCLKSOURCE_PLL;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
Error_Handler();
}
/* Peripheral clock enable */
__HAL_RCC_FDCAN_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
/**FDCAN1 GPIO Configuration
PD0 ------> FDCAN1_RX
PD1 ------> FDCAN1_TX
*/
GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF9_FDCAN1;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/* USER CODE BEGIN FDCAN1_MspInit 1 */
/* USER CODE END FDCAN1_MspInit 1 */
}
}
Note the use of 85 to see it clearly on the oscillsocope, but I am not getting anything on the TX line.
How is the message sent after it is written to RAM?
Thanks.
