Question
Unable to receive CAN messages between two STM32FI-Discovery Boards
I'm trying to communicate over CAN using the HAL_CAN library between two STM32F boards. Specifically the issue seems to be in receiving messages. Following the documentation:
==============================================================================
##### How to use this driver #####
[..]
(#) Initialize the CAN low level resources by implementing the HAL_CAN_MspInit():
(++) Enable the CAN interface clock using __HAL_RCC_CANx_CLK_ENABLE()
(++) Configure CAN pins
(+++) Enable the clock for the CAN GPIOs
(+++) Configure CAN pins as alternate function open-drain
(++) In case of using interrupts (e.g. HAL_CAN_ActivateNotification())
(+++) Configure the CAN interrupt priority using
HAL_NVIC_SetPriority()
(+++) Enable the CAN IRQ handler using HAL_NVIC_EnableIRQ()
(+++) In CAN IRQ handler, call HAL_CAN_IRQHandler()
(#) Initialize the CAN peripheral using HAL_CAN_Init() function. This
function resorts to HAL_CAN_MspInit() for low-level initialization.
(#) Configure the reception filters using the following configuration
functions:
(++) HAL_CAN_ConfigFilter()
(#) Start the CAN module using HAL_CAN_Start() function. At this level
the node is active on the bus: it receive messages, and can send
messages.
(#) To manage messages transmission, the following Tx control functions
can be used:
(++) HAL_CAN_AddTxMessage() to request transmission of a new
message.
(++) HAL_CAN_AbortTxRequest() to abort transmission of a pending
message.
(++) HAL_CAN_GetTxMailboxesFreeLevel() to get the number of free Tx
mailboxes.
(++) HAL_CAN_IsTxMessagePending() to check if a message is pending
in a Tx mailbox.
(++) HAL_CAN_GetTxTimestamp() to get the timestamp of Tx message
sent, if time triggered communication mode is enabled.
(#) When a message is received into the CAN Rx FIFOs, it can be retrieved
using the HAL_CAN_GetRxMessage() function. The function
HAL_CAN_GetRxFifoFillLevel() allows to know how many Rx message are
stored in the Rx Fifo.
(#) Calling the HAL_CAN_Stop() function stops the CAN module.
(#) The deinitialization is achieved with HAL_CAN_DeInit() function.
*** Polling mode operation ***
==============================
[..]
(#) Reception:
(++) Monitor reception of message using HAL_CAN_GetRxFifoFillLevel()
until at least one message is received.
(++) Then get the message using HAL_CAN_GetRxMessage().
(#) Transmission:
(++) Monitor the Tx mailboxes availability until at least one Tx
mailbox is free, using HAL_CAN_GetTxMailboxesFreeLevel().
(++) Then request transmission of a message using
HAL_CAN_AddTxMessage().
*** Interrupt mode operation ***
================================
[..]
(#) Notifications are activated using HAL_CAN_ActivateNotification()
function. Then, the process can be controlled through the
available user callbacks: HAL_CAN_xxxCallback(), using same APIs
HAL_CAN_GetRxMessage() and HAL_CAN_AddTxMessage().
(#) Notifications can be deactivated using
HAL_CAN_DeactivateNotification() function.
(#) Special care should be taken for CAN_IT_RX_FIFO0_MSG_PENDING and
CAN_IT_RX_FIFO1_MSG_PENDING notifications. These notifications trig
the callbacks HAL_CAN_RxFIFO0MsgPendingCallback() and
HAL_CAN_RxFIFO1MsgPendingCallback(). User has two possible options
here.
(++) Directly get the Rx message in the callback, using
HAL_CAN_GetRxMessage().
(++) Or deactivate the notification in the callback without
getting the Rx message. The Rx message can then be got later
using HAL_CAN_GetRxMessage(). Once the Rx message have been
read, the notification can be activated again.- I'm calling HAL_CAN_Init, which in turns calls HAL_CAN_MspInit setting the clock, enabling the gpios and configuring the can pins as alternate function open drain. As I'm using interrupts it also sets the receive interrupt as:
HAL_NVIC_SetPriority(CAN1_RX0_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(CAN1_RX0_IRQn);2. Reception filters are being set as follows using HAL_CAN_ConfigFilter(), and no error is returned:
sFilterConfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
sFilterConfig.FilterIdHigh = 0;
sFilterConfig.FilterIdLow = 0;
sFilterConfig.FilterMaskIdHigh = 0;
sFilterConfig.FilterMaskIdLow = 0;
sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
sFilterConfig.FilterActivation = ENABLE;
sFilterConfig.FilterBank = 0;
sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
sFilterConfig.SlaveStartFilterBank = 14;
HAL_CAN_ConfigFilter(&hcan1, &sFilterConfig)3. HAL_CAN_Start is called and no error is returned:
HAL_CAN_Start(&hcan1)4. Using an interrupt triggered by pressing the blue pushbutton a message is sent:
void EXTI0_IRQHandler(void)
{
/* USER CODE BEGIN EXTI0_IRQn 0 */
for(int n=0;n<1000000;n++);
if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0) == GPIO_PIN_SET) {
a++;
if(HAL_CAN_GetTxMailboxesFreeLevel(&hcan1)){
if(HAL_CAN_AddTxMessage(&hcan1, &pHeader, &a, &TxMailbox)==HAL_OK){
if(HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_6) == GPIO_PIN_SET){
HAL_GPIO_WritePin(GPIOG, GPIO_PIN_6, GPIO_PIN_RESET);
} else{
HAL_GPIO_WritePin(GPIOG, GPIO_PIN_6, GPIO_PIN_SET);
}
}
}
}5. I've verified the message is pending as the following returns a positive value:
HAL_CAN_IsTxMessagePending(&hcan1, TxMailbox)6. However the following interrupt that should be triggered when a messaged is available to be received is never triggered:
void CAN1_RX0_IRQHandler(void)
{
/* USER CODE BEGIN CAN1_RX0_IRQn 0 */
/* USER CODE END CAN1_RX0_IRQn 0 */
HAL_CAN_IRQHandler(&hcan1);
/* USER CODE BEGIN CAN1_RX0_IRQn 1 */
HAL_CAN_GetRxMessage(&hcan1, CAN_RX_FIFO0, &pRxHeader, &r);
HAL_GPIO_WritePin(GPIOK, GPIO_PIN_3, GPIO_PIN_RESET);
/* USER CODE END CAN1_RX0_IRQn 1 */
}Other notes:
- Have verified the transceivers being used are both receiving 3.3V
Any help would be greatly appreciated, Rus