STM32F446RE CAN in LOOPBACK MODE

RN · ‎2018-05-09

Posted on May 10, 2018 at 04:45

Hello Everyone,

I want to test the CAN1 peripheral in loop back mode. please suggest me the required steps .

I am using STM32F446RE nucleo board and currently i want to test without transceivers

So far i have done this .

/* CAN1 init function */

static void MX_CAN1_Init(void)

{

hcan1.Instance = CAN1;

hcan1.Init.Prescaler = 16;

hcan1.Init.Mode = CAN_MODE_LOOPBACK;

hcan1.Init.SyncJumpWidth = CAN_SJW_1TQ;

hcan1.Init.TimeSeg1 = CAN_BS1_1TQ;

hcan1.Init.TimeSeg2 = CAN_BS2_1TQ;

hcan1.Init.TimeTriggeredMode = DISABLE;

hcan1.Init.AutoBusOff = ENABLE;

hcan1.Init.AutoWakeUp = DISABLE;

hcan1.Init.AutoRetransmission = DISABLE;

hcan1.Init.ReceiveFifoLocked = DISABLE;

hcan1.Init.TransmitFifoPriority = DISABLE;

if (HAL_CAN_Init(&hcan1) != HAL_OK)

{

_Error_Handler(__FILE__, __LINE__);

}

/*♯♯-2- Configure the CAN Filter ♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯*/

sFilterConfig.FilterBank = 0;

sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;

sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;

sFilterConfig.FilterIdHigh = 0x0000;

sFilterConfig.FilterIdLow = 0x0000;

sFilterConfig.FilterMaskIdHigh = 0x0000;

sFilterConfig.FilterMaskIdLow = 0x0000;

sFilterConfig.FilterFIFOAssignment = CAN_RX_FIFO0;

sFilterConfig.FilterActivation = ENABLE;

sFilterConfig.SlaveStartFilterBank = 14;

if(HAL_CAN_ConfigFilter(&hcan1, &sFilterConfig) != HAL_OK)

{

/* Filter configuration Error */

Error_Handler();

}

uint8_t aData[]= {0xA5,0X55};

uint8_t RxData[8];

CAN_TxHeaderTypeDef tXheader;

CAN_RxHeaderTypeDef RxHeader;

tXheader.StdId = 0x11;

tXheader.ExtId = 0;

tXheader.IDE = CAN_ID_STD;

tXheader.RTR = CAN_RTR_DATA;

tXheader.TransmitGlobalTime = DISABLE;

tXheader.DLC = 2;

HAL_StatusTypeDef Status;

/*♯♯-3- Start the CAN peripheral ♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯*/

if (HAL_CAN_Start(&hcan1) != HAL_OK)

{

/* Start Error */

Error_Handler();

}

Status = HAL_CAN_AddTxMessage(&hcan1,&tXheader,aData,&TxMailbox);

if(Status != HAL_OK)

{

Error_Handler();

}

/* Wait transmission complete */

while(HAL_CAN_GetTxMailboxesFreeLevel(&hcan1) != 3) {}

/*♯♯-5- Start the Reception process ♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯*/

if(HAL_CAN_GetRxFifoFillLevel(&hcan1, CAN_RX_FIFO0) != 1)

{

/* Reception Missing */

Error_Handler();

}

Start the Reception process : This function is entering in to error_handler .

Could you please help to solve this issue ?

Thank you !

#can-interface #stm32f4xx-can-bus-error #stm32

Amel NASRI · ‎2018-05-16

Posted on May 16, 2018 at 16:35

Hi

balckiran

‌,

In the package STM32CubeF4 package, you find a ready to use example for CAN in loopback mode with STM32F446 device.

It is underSTM32Cube_FW_F4_V1.0\Projects\STM32446E_EVAL\Examples\CAN\CAN_Loopback.

You find there a readme.txt file that describes how to run the example.

Compare the one I provided with your generated project and add same APIs calls to check again.

-Amel

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

RN · ‎2018-05-18

Posted on May 18, 2018 at 09:07

Amel,

Thanks for the help, yes i indeed referred to the code you mentioned but the problem is the transmission is not successful , i debugged the IRQ and the control is going to TERR ( Transmission error). Actually i am using silent loop back without any transceiver.

T J · ‎2018-05-18

Posted on May 18, 2018 at 09:45

If you don't have a transceiver, then you need a pull-up on Can-Rx.processor pin

T J · ‎2018-05-18

Posted on May 18, 2018 at 12:17

ok,

then you need to purchase a Commercial CanBus testing unit, like CanDo from the UK.

I set the CanDo unit to transmit packets every second.

I worked on the receiver first.

This requires a transceiver chip and a 120ohm terminator if your wires are over 10Meters.

it is impossible to debug your code from here.

but this looks odd. if(HAL_CAN_GetRxFifoFillLevel(&hcan1, CAN_RX_FIFO0) != 1)

 char canFifo1FullFlag = CAN1->RF1R & CAN_RF1R_FMP1;
 if (canFifo1FullFlag) {
 {
 readCanBytecount = (CAN1->sFIFOMailBox[1].RDTR & 0x0f); 
 canRxMsgBottomWord[canRxMsgIN] = CAN1->sFIFOMailBox[1].RDLR; // load all eight bytes in 2 cycles
 canRxMsgTopWord [canRxMsgIN] = CAN1->sFIFOMailBox[1].RDHR;
 canRxMsgID[canRxMsgIN] = CAN1->sFIFOMailBox[1].RIR >> 21;
 CAN1->RF1R |= CAN_RF1R_RFOM1; // release FIFO
 canRxMsgLength[canRxMsgIN] = readCanBytecount; // was 0x10+ to signify FIFO1
 ++canRxMsgIN &= 0x3F; // 64 entries only
 canRxMsgTableEMPTY = false;
 if (canRxMsgIN == canRxMsgOUT) canRxMsgTableFULL = true;
 }
 CAN1->IER |= CAN_IER_FMPIE1; // (11) Set FIFO1 message pending IT enable
 }�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

RN · ‎2018-05-18

Posted on May 18, 2018 at 10:58

yes . i do have pull up on RX. i connected to +vcc via 3.3K resistor