FDCAN on STM32G491RE: Tx message truncated. 8 bytes sent instead of 12 bytes

[Qin1]

I am using STM32G491RE - NUCLEO. connected to the ADM3055e CAN Transceiver 

Currently I am trying to send 12 Bytes of Data from IXXAT Terminal over to FDCAN1 which receives the message fine and then Output the Message on FDCAN2 though a buffer. So My logic is when a message pass the filter it gets called by the Fifo0Callback and push it to a buffer below. This works fine the buffer also get the full 12Bytes of data same FD format and everything checked out.

But when I try to add the message to HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan2, &TxHeader2, TxData2). Where TxData is the dequeued message from the buffer and copys the 12Bytes. The message somehow gets truncated to 8Bytes on output. 

Heck, when I add "if (HAL_FDCAN_GetTxFifoFreeLevel(&hfdcan2) > 0)", It somehow says it is full even when starting the code.

I have been suspecting because I cant set the HAL_FDCAN_ConfigTxBufferElementSize and HAL_FDCAN_ConfigRxBufferElementSize or even the messageRam offset like i could in the STM32H7 series. which may be causing the issue. Any Ideas on what I should do? 

Let me know if you need more information.

@LCE @mƎALLEm 
Thanks in advance! 

void HAL_FDCAN_RxFifo0Callback(FDCAN_HandleTypeDef *hfdcan, uint32_t RxFifo0ITs)
{
	if((RxFifo0ITs & FDCAN_IT_RX_FIFO0_NEW_MESSAGE) != RESET)
	{
		if (hfdcan->Instance == FDCAN2)
		{
...
		}
		else if (hfdcan->Instance == FDCAN1)
		{
			if (HAL_FDCAN_GetRxMessage(hfdcan, FDCAN_RX_FIFO0, &RxHeader1, RxData1) == HAL_OK)
			{
				uint8_t len = Can_DlcToBytes(RxHeader1.DataLength);
				if (!CanRxBuffer_EnqueueFromISR1(RxHeader1.Identifier, RxData1, len)) {
					FDCAN1_LED_State = LED_FIFO0_ERROR;
				} else {
					FDCAN1_LED_State = LED_STORE_BUFFER;
				}
			}
			else {
				FDCAN1_LED_State = LED_FIFO0_ERROR;
			}
		}

[Qin1]

I did that and still the same result

[mƎALLEm]

I don't have the device to test and debug. I think at this stage better to create a simple project where you simply send 12 bytes to your analyzer and test. 

You can also try the Loopback mode.

[Qin1]

Alright I'll do that and let you know how it goes. Thank you for the help @mƎALLEm 

On a side note may I ask how the RAM allocation and Tx / Rx BufferElementSize can be configured on G4 Series. As in cubeMX it doesnt give me the option to like the H7 series. Or is that done automatically by the core? 

[mƎALLEm]

Better to separate questions here. Please create another thread for that question.

[Qin1 · Accepted solution]

Ok I found the issue....It's ridiculous simple mistake but it solved my issue.

I realised that when configuring TxHeader FDFormat my mistake was:
TxHeader1.FDFormat = FDCAN_FRAME_FD_BRS;

however it should be 
TxHeader2.FDFormat = FDCAN_FD_CAN;

But anyways that solved my issue.