Hello @here, i am currently trying to set up my CAN protocol using stm32f103c8t6. I intend to use it in loop back mode just for test, I am having issues, the frequency is 72MHz and my bus(APB1ENR) is 36MHz, my baudrate is 250kb/s. After initialization, it gets stuck at
CAN1->MCR &= ~CAN_MCR_INRQ;
while (CAN1->MSR & CAN_MSR_INAK) ; // Wait for normal mode

void CAN1_Init()
{
RCC->APB2ENR |= 1 << 2; // enabling GPIOA clock RCC->APB1ENR &= ~(1 << 25); // enabling CAN1 clock RCC->APB1ENR |= 1 << 25; // enabling CAN1 clock delay_ms(1000); RCC->APB2ENR |= 1 << 0; // enabling AFIOEN clock GPIOA->CRH &= ~(0x0F << 12); // CAN_RX PA11 GPIOA->CRH |= (0x0B << 12); // GPIOA->CRH &= ~(0x0F << 16); // CAN_TX PA12 GPIOA->CRH |= (0x0B << 16); // // CAN1->MCR &= ~(1 << 0); // Enter initialization mode CAN1->MCR |= (1 << 0); while ((CAN1->MSR & 0x01) != 1)
;

CAN1->MCR &= ~(1 << 1); // EXIT FROM SLEEP MODE while ((CAN1->MSR & 0X02) != 0)
;

CAN1->BTR |= (1 << 30); // ENABLE LOOP BACK MODE CAN1->BTR &= ~(1 << 31); CAN1->MCR &= ~(1 << 6); // AUTO BUSS OFF DISABLE CAN1->MCR &= ~(1 << 4); // AUTO RETRANSMISSION ENABLED CAN1->MCR &= ~(1 << 5); // DISABLE AUTO WAKEUP CAN1->MCR &= ~(1 << 3); // RECEIVED FIFO DISABLED CAN1->MCR &= ~(1 << 7); // TIME TRIGERRED DISABLE CAN1->MCR &= ~(1 << 2); // PRIORITY DRIVEN BY IDENTIFIER // Next is the settigs for the CAn trigger CAN1->BTR &= ~(3 << 24); // SETTING SJW TO 1 CAN1->BTR |= (0 << 24); CAN1->BTR &= ~(0x3FF << 0); // PRESCALER IS 9, BUT 8 IS SENT for 250kbs CAN1->BTR |= (8 << 0); CAN1->BTR &= ~(0x0F << 16); CAN1->BTR |= (12 << 16); // TIMER SEGMENT 1 TO BE DECIMAL 13 CAN1->MCR &= ~(1 << 7); // Time Triggered Disable CAN1->BTR &= ~(0x07 << 20); CAN1->BTR |= (1 << 20); // TIMER SEGMENT 2 TO BE DECIMAL 2 CAN1->MCR &= ~CAN_MCR_INRQ;
while (CAN1->MSR & CAN_MSR_INAK)
; // Wait for normal mode
}
I will appreciate if someone can assist