STM32F4 Discovery and CAN programming - c

Question

I am trying to start learning programming and I am trying to get this code to work: https://github.com/espruino/Espruino/blob/master/targetlibs/stm32f4/lib/stm32f4xx_can.c
I am using Atollic TruStudio Lite.
I did the basic LED blinking code with Discovery, but other than that. I have no clue how to do this.
I don't get how am i supposed to simulate CAN message (and other things) via STM32.
I am a total beginner, so please, don't rip my throat out.
Thanks

Answer 1

Here's an example of a CAN loopback you can try. It's a CAN loopback test. It's in the stm32f4 examples that you can download from the STM website. This is for an STM32439 eval board but it should work on a discovery. (Both are STM32F4 chips).
#define USE_CAN1
/* Uncomment the line below if you will use the CAN 2 peripheral */
/* #define USE_CAN2 */
#ifdef USE_CAN1
#define CANx CAN1
#define CAN_CLK RCC_APB1Periph_CAN1
#else /* USE_CAN2 */
#define CANx CAN2
#define CAN_CLK (RCC_APB1Periph_CAN1 | RCC_APB1Periph_CAN2)
#endif /* USE_CAN1 */
typedef enum {FAILED = 0, PASSED = !FAILED} TestStatus;
__IO uint32_t ret = 0; /* for return of the interrupt handling */
volatile TestStatus TestRx;
TestStatus CAN_Polling(void);
int main(void) {
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
files (startup_stm32f40_41xxx.s/startup_stm32f427_437xx.s/startup_stm32f429_439xx.s)
before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f4xx.c file
*/
/* CANx Periph clock enable */
RCC_APB1PeriphClockCmd(CAN_CLK, ENABLE);
/* Initialize LEDs mounted on EVAL board */
STM_EVAL_LEDInit(LED1);
STM_EVAL_LEDInit(LED2);
/* CAN transmit at 125Kb/s and receive by polling in loopback mode */
TestRx = CAN_Polling();
if (TestRx != FAILED) { /* OK */
/* Turn on LED1 */
STM_EVAL_LEDOn(LED1);
} else { /* KO */
/* Turn on LED2 */
STM_EVAL_LEDOn(LED2);
}
/* Infinite loop */
while (1) { }
}
/**
* #brief Configures the CAN, transmit and receive by polling
* #param None
* #retval PASSED if the reception is well done, FAILED in other case
*/
TestStatus CAN_Polling(void) {
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
CanTxMsg TxMessage;
CanRxMsg RxMessage;
uint32_t uwCounter = 0;
uint8_t TransmitMailbox = 0;
/* CAN register init */
CAN_DeInit(CANx);
/* CAN cell init */
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 Baudrate = 175kbps (CAN clocked at 42 MHz) */
CAN_InitStructure.CAN_BS1 = CAN_BS1_6tq;
CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
CAN_InitStructure.CAN_Prescaler = 16;
CAN_Init(CANx, &CAN_InitStructure);
/* CAN filter init */
#ifdef USE_CAN1
CAN_FilterInitStructure.CAN_FilterNumber = 0;
#else /* USE_CAN2 */
CAN_FilterInitStructure.CAN_FilterNumber = 14;
#endif /* USE_CAN1 */
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 */
TxMessage.StdId = 0x11;
TxMessage.RTR = CAN_RTR_DATA;
TxMessage.IDE = CAN_ID_STD;
TxMessage.DLC = 2;
TxMessage.Data[0] = 0xCA;
TxMessage.Data[1] = 0xFE;
TransmitMailbox = CAN_Transmit(CANx, &TxMessage);
uwCounter = 0;
while((CAN_TransmitStatus(CANx, TransmitMailbox) != CANTXOK) && (uwCounter != 0xFFFF)) {
uwCounter++;
}
uwCounter = 0;
while((CAN_MessagePending(CANx, CAN_FIFO0) < 1) && (uwCounter != 0xFFFF)) {
uwCounter++;
}
/* receive */
RxMessage.StdId = 0x00;
RxMessage.IDE = CAN_ID_STD;
RxMessage.DLC = 0;
RxMessage.Data[0] = 0x00;
RxMessage.Data[1] = 0x00;
CAN_Receive(CANx, CAN_FIFO0, &RxMessage);
if (RxMessage.StdId != 0x11) {
return FAILED;
}
if (RxMessage.IDE != CAN_ID_STD) {
return FAILED;
}
if (RxMessage.DLC != 2) {
return FAILED;
}
if ((RxMessage.Data[0]<<8|RxMessage.Data[1]) != 0xCAFE) {
return FAILED;
}
return PASSED; /* Test Passed */
}