Posted on October 10, 2014 at 19:25Hi ST forums,
I wrote a piece of code to try out CAN_TX and CAN_RX to loopback the data into from PD1 (CAN1_TX) into PD0 (CAN1_RX). It seems to be working (I get back what I sent). Then I realized even if I unplug the jumper from PD0 to PD1 it is still receiving CAN data, (Receive LED on, data streaming in).
Is TxMessage.Data connected to RxMessage.Data? Please take a look:
&sharpinclude ''stm32f4xx_gpio.h''
&sharpinclude ''stm32f4xx_rcc.h''
&sharpinclude ''stm32f4xx_can.h''
&sharpinclude ''misc.h''
&sharpinclude ''semihosting.h''
GPIO_InitTypeDef GPIO_InitStructure;
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
CanTxMsg TxMessage;
CanRxMsg RxMessage;
void CAN_Config(void);
void NVIC_Config(void);
void CAN_Config(void)
{
/* Enable GPIO clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
/* Connect CAN pins to AF9 */
GPIO_PinAFConfig(GPIOD, GPIO_PinSource0, GPIO_AF_CAN1);
GPIO_PinAFConfig(GPIOD, GPIO_PinSource1, GPIO_AF_CAN1);
/* Configure CAN RX and TX pins */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_Init(GPIOD, &GPIO_InitStructure);
//CAN1
/* CAN register init */
CAN_DeInit(CAN1);
/* CAN cell init */
CAN_DBGFreeze(CAN1, DISABLE);
CAN_InitStructure.CAN_TTCM = DISABLE;
CAN_InitStructure.CAN_ABOM = DISABLE;
CAN_InitStructure.CAN_AWUM = DISABLE;
CAN_InitStructure.CAN_NART = DISABLE;
CAN_InitStructure.CAN_RFLM = DISABLE;
CAN_InitStructure.CAN_TXFP = DISABLE;
CAN_InitStructure.CAN_Mode = CAN_Mode_LoopBack;
CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1 = CAN_BS1_14tq;
CAN_InitStructure.CAN_BS2 = CAN_BS2_6tq;
CAN_InitStructure.CAN_Prescaler = 200; //CAN baud rate 10kbits
CAN_Init(CAN1, &CAN_InitStructure);
/* CAN filter init */
CAN_FilterInitStructure.CAN_FilterNumber = 0;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;
CAN_FilterInitStructure.CAN_FilterIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit(&CAN_FilterInitStructure);
/* Transmit Structure preparation */
TxMessage.StdId = 0x321;
TxMessage.ExtId = 0x00;
TxMessage.RTR = CAN_RTR_DATA;
TxMessage.IDE = CAN_ID_STD;
TxMessage.DLC = 1;
TxMessage.Data[0] = 0x55;
/* Enable FIFO 0 message pending Interrupt */
CAN_ITConfig(CAN1, CAN_IT_FMP0, ENABLE);
}
void NVIC_Config(void)
{
NVIC_InitStructure.NVIC_IRQChannel = CAN1_RX0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
void Init_RxMes(CanRxMsg *RxMessage)
{
uint8_t i = 0;
RxMessage->StdId = 0x00;
RxMessage->ExtId = 0x00;
RxMessage->IDE = CAN_ID_STD;
RxMessage->DLC = 8;
RxMessage->FMI = 0;
for (i = 0;i<8;i++)
{
RxMessage->Data[i] = 0x00;
}
}
int main(void)
{
CAN_Config();
NVIC_Config();
Init_RxMes(&RxMessage);
/* Infinite loop */
while (1)
{
CAN_Transmit(CAN1, &TxMessage);
printf(''\nData Received (0): %X'',RxMessage.Data[0]);
// printf(''\nData Received (1): %d'',RxMessage.Data[1]);
// printf(''\nData Received (2): %d'',RxMessage.Data[2]);
// printf(''\nData Received (3): %d'',RxMessage.Data[3]);
// printf(''\nData Received (4): %d'',RxMessage.Data[4]);
// printf(''\nData Received (5): %d'',RxMessage.Data[5]);
// printf(''\nData Received (6): %d'',RxMessage.Data[6]);
// printf(''\nData Received (7): %d'',RxMessage.Data[7]);
}
}
void CAN1_RX0_IRQHandler(void)
{
CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);
GPIOD->BSRRL = GPIO_Pin_12;
}
#!weird
