HAL_FDCAN_GetTxFifoFreeLevel always returns 0

[killa-pixel]

On the M4 core of a stm32mp157 I am using FIFO based FDCan communication.

Messages are sent and received just fine but I think when I send too many messages in a short time some messages are getting lost.

So I added a call to HAL_FDCAN_GetTxFifoFreeLevel before calling HAL_FDCAN_AddMessageToTxFifoQ to make sure there is space in the FIFO, but HAL_FDCAN_GetTxFifoFreeLevel always returns 0.

Here some parts of my fdcan configuration:

RxFifo0ElmtsNbr = 8;

RxFifo0ElmtSize = FDCAN_DATA_BYTES_8;

RxFifo1ElmtsNbr = 0;

RxFifo1ElmtSize = FDCAN_DATA_BYTES_8;

RxBuffersNbr = 0;

RxBufferSize = FDCAN_DATA_BYTES_8;

TxEventsNbr = 0;

TxBuffersNbr = 0;

TxFifoQueueElmtsNbr = 35;

TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;

TxElmtSize = FDCAN_DATA_BYTES_8;

What am I missing?

[Karl Yamashita]

Create a queue to hold your Tx messages. When you successfully send a message then you can increment your pointer to the next queue to be transmitted.