Electronic – CAN communication not working

I made the following circuit. STM32's are STM32F103C8T6 (Blue Pills).
I left out the obvious wires:

• All four components grounded together
• Supplied 5V to RX TJA 1050 from RX STM32
• Supplied 5V to TX TJA 1050 from TX STM32

^{simulate this circuit – Schematic created using CircuitLab}

The TJA's are these ones:

Most important software running on TX STM32:

/* CAN init function */
static void MX_CAN_Init(void)
{

  static CanRxMsgTypeDef CanRX;
  static CanTxMsgTypeDef CanTX;
  CAN_FilterConfTypeDef sFilterConfig;

  hcan.Instance = CAN1;

  hcan.pRxMsg = &CanRX;
  hcan.pTxMsg = &CanTX;

  hcan.Init.Prescaler = 8;
  hcan.Init.Mode = CAN_MODE_NORMAL;
  hcan.Init.SJW = CAN_SJW_1TQ;
  hcan.Init.BS1 = CAN_BS1_12TQ;
  hcan.Init.BS2 = CAN_BS2_5TQ;
  hcan.Init.TTCM = DISABLE;
  hcan.Init.ABOM = DISABLE;
  hcan.Init.AWUM = DISABLE;
  hcan.Init.NART = DISABLE;
  hcan.Init.RFLM = DISABLE;
  hcan.Init.TXFP = DISABLE;
  if (HAL_CAN_Init(&hcan) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }


  sFilterConfig.FilterNumber = 0;
  sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
  sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
  sFilterConfig.FilterIdHigh = 0x07ff;
  sFilterConfig.FilterIdLow = 0x0000;
  sFilterConfig.FilterMaskIdHigh = 0x07ff;
  sFilterConfig.FilterMaskIdLow = 0x0000;
  sFilterConfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
  sFilterConfig.FilterActivation = ENABLE;
  sFilterConfig.BankNumber = 14;

  if (HAL_CAN_ConfigFilter(&hcan, &sFilterConfig) != HAL_OK)
  {
      Error_Handler();
  }
}

In main:

..
hcan.pTxMsg->StdId = 0x100;
hcan.pTxMsg->ExtId = 0x01;
hcan.pTxMsg->IDE = CAN_RTR_DATA;
hcan.pTxMsg->IDE = CAN_ID_STD;
hcan.pTxMsg->DLC = 2;

while (1)
{
  hcan.pTxMsg->Data[0] = 0x10;
  hcan.pTxMsg->Data[1] = 0x1;

      HAL_CAN_Transmit(&hcan, 10)
  HAL_Delay(1000);
 }

And on TX STM32 the same code for initializing the CAN, and following code in main:

if (HAL_CAN_Receive_IT(&hcan, CAN_FIFO0) != HAL_OK)
{
  Error_Handler();
}


void HAL_CAN_RxCpltCallback(CAN_HandleTypeDef* CanHandle)
{
if ((CanHandle->pRxMsg->StdId == 0x100) &&
    (CanHandle->pRxMsg->IDE   == CAN_ID_STD) &&
    (CanHandle->pRxMsg->DLC   == 2))
{
    printf("1");
}

However, the callback is never called.

What I see with a logic analyzer:

• CANH (Channel 2) and CANL (Channel 0) receive info
• Channel 4 is connected to RX STM32, CAN RX and does not receive anything

I see X's in the screenshot below, not sure if this is a problem.

What I did

• Replaced TJA's, no difference
• Put breakpoints on various places, everything seems ok, except the callback

Question:

• What should I change to be able to receive info at RX STM32, CAN RX?

Update

I found out there is some transmission problem:

within

HAL_StatusTypeDef HAL_CAN_Transmit(CAN_HandleTypeDef* hcan, uint32_t Timeout)

there occurs a timeout (last line):

while(!(__HAL_CAN_TRANSMIT_STATUS(hcan, transmitmailbox)))
{
  /* Check for the Timeout */
  if(Timeout != HAL_MAX_DELAY)
  {
    if((Timeout == 0U) || ((HAL_GetTick()-tickstart) > Timeout))
    {
      hcan->State = HAL_CAN_STATE_TIMEOUT;

      /* Cancel transmission */
      __HAL_CAN_CANCEL_TRANSMIT(hcan, transmitmailbox);

      /* Process unlocked */
      __HAL_UNLOCK(hcan);
      return HAL_TIMEOUT;
    }
  }
}

I have not found out where this error comes from.

Also because of the error, nothing is send afterwards.

No more time now, I will check more tomorrow or Tuesday evening.

Other checks:

• Oscilloscope: not checked yet
• Resistance between CANL and CANH: 61.4 ohm (while not transmitting), when transmitting slightly less.
• Voltage while not sending between CANL and CANH is 0 V
• Adding a 120 R resistor between CANL and CANH does not make any difference (still a HAL_TIMEOUT).

Update

Still limited time, but I did a test without using transceivers, but directly with a simple circuit as described in this document (thanks to Maple).
Relevant part:

However the result is still not working. The receiver sides are ALMOST equal, but the transmitter transmits barely nothing

• Channel 1: Transmitter TX
• Channel 2: Transmitter RX
• Channel 3: Receiver TX
• Channel 4: Receiver RX

On the detail (below), in the selected ramp there can be seen a slight difference (there are more of those). Since they are connected together, I would not expect these though, but maybe my cheap logic analyzer (5$) might cause these.