CAN BUS and stuff bits
- June 28, 2019
- 5 replies
- 2311 views
Hello,
I'm using a ST32F466 trying to connect a personal board to a PEAK analizer.
The code is generated in part by MS32Cube, and in part by me on TrueStudio 9.2 using HAL libraries.
After setting the CAN1, (HAL_CAN_MspInit()), I have configured the CANHeader (configCANHeader()), the filter (configCANFilter())
I start the CAN (HAL_CAN_Start()), and activate IRQ on
-- Transmission complete,
-- SCE
-- Reception
Every second I try to send a frame using HAL_CAN_AddTxMessage().
Everithing seem correct if I send frames with NO SUFF BITS ( for example 8 times 0x55).
If I try to send frames with many STUFF BITS (for example 8 times 0x50) after first attempt (correct), an ERROR FRAME IS GENERATED and in the ESR register I find LEC=3
The tracks I have registered are on the micro, before the level transceiver.
Some idea?
The code in the main:
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_CAN1_Init();
configCANHeader(); /* CAN Header*/
configCANFilter(); /* CAN Filter*/
HAL_CAN_Start(&hcan1);
HAL_CAN_ActivateNotification(&hcan1,CAN_IT_TX_MAILBOX_EMPTY); /*IRQ transmission enabled*/
HAL_CAN_ActivateNotification(&hcan1,CAN_IT_LAST_ERROR_CODE); /*IRQ SCE enabled*/
HAL_CAN_ActivateNotification(&hcan1,CAN_IT_RX_FIFO0_MSG_PENDING);/*IRQ reception enabled*/
while (1)
{
HAL_Delay(1000);
for(uint8_t i=0;i<8;i++)
TxData[i]=0x55; //in this case transmission is correct
HAL_CAN_AddTxMessage(&hcan1, &TxHeader,TxData, &TxMailBox);
}
}
The code for initialization:
void MX_CAN1_Init(void)
{
hcan1.Instance = CAN1;
hcan1.Init.Prescaler = 12; //f BUS =45Mhz 250.000 BPS
hcan1.Init.Mode = CAN_MODE_NORMAL;
hcan1.Init.SyncJumpWidth = CAN_SJW_1TQ; //from 1 to 4
hcan1.Init.TimeSeg1 = CAN_BS1_12TQ; //from 1 to 16
hcan1.Init.TimeSeg2 = CAN_BS2_2TQ; //from 1 to 8
hcan1.Init.TimeTriggeredMode = DISABLE;
hcan1.Init.AutoBusOff = DISABLE;
hcan1.Init.AutoWakeUp = ENABLE;
hcan1.Init.AutoRetransmission = DISABLE;
hcan1.Init.ReceiveFifoLocked = DISABLE;
hcan1.Init.TransmitFifoPriority = DISABLE;
if (HAL_CAN_Init(&hcan1) != HAL_OK)
{
Error_Handler();
}
}
void HAL_CAN_MspInit(CAN_HandleTypeDef* canHandle)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(canHandle->Instance==CAN1)
{
HAL_RCC_CAN1_CLK_ENABLED++;
if(HAL_RCC_CAN1_CLK_ENABLED==1){
__HAL_RCC_CAN1_CLK_ENABLE();
}
__HAL_RCC_GPIOA_CLK_ENABLE();
GPIO_InitStruct.Pin = GPIO_PIN_11|GPIO_PIN_12;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF9_CAN1;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* CAN1 interrupt Init */
HAL_NVIC_SetPriority(CAN1_TX_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(CAN1_TX_IRQn);
HAL_NVIC_SetPriority(CAN1_SCE_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(CAN1_SCE_IRQn);
HAL_NVIC_SetPriority(CAN1_RX0_IRQn, 0, 2);
HAL_NVIC_EnableIRQ(CAN1_RX0_IRQn);
}
}
code for header:
void configCANHeader(void)
{
TxHeader.DLC=8; /* Specifies the length of the frame that will be transmitted.
This parameter must be a number between Min_Data = 0 and Max_Data = 8. */
TxHeader.IDE=CAN_ID_STD; /* Standard Id 11 bit*/
TxHeader.RTR=CAN_RTR_DATA; /* Specifies the type of frame for the message that will be transmitted.
CAN_RTR_DATA (0x00000000U=Data frame) or CAN_RTR_REMOTE (0x00000002U=Remote frame) */
TxHeader.StdId=0x5B9; /* Specifies the standard identifier. This parameter must be a number between Min_Data = 0 and Max_Data = 0x7FF. */
/*on 11 bit-->> 101 1011 1010 = 0x5B9*/
}
coide for the filter:
void configCANFilter(void)
{
sFilterConfig.FilterFIFOAssignment=CAN_FILTER_FIFO0;
sFilterConfig.FilterIdHigh=245<<5; //0001 1110 1010 0000
sFilterConfig.FilterIdLow=0; //quindi su 32 bit 0001 1110 1010 0000 0000 0000 0000 0000
sFilterConfig.FilterMaskIdHigh=0;
sFilterConfig.FilterMaskIdLow=0; //mask su 32 bit 0000 0000 0000 0000 0000 0000 0000 0000
sFilterConfig.FilterScale=CAN_FILTERSCALE_32BIT;
sFilterConfig.FilterActivation=ENABLE;
HAL_CAN_ConfigFilter(&hcan1, &sFilterConfig);
}