STM32 CAN bus usage

This debugging uses the STM32 core board of Zhuhai D-Chip Technology. This core board contains a CAN bus driver. It can easily connect and communicate with multiple industrial devices at the same time.

The CAN bus of the STM32 processor has multiple working modes. This test is in normal mode. To use it in normal mode, you first need to initialize the registers and enable related functional components.

The first step is to initialize the GPIO and clock. The CAN bus GPIO of STM32F103C is GPIOA_PIN_11 and GPIOA_PIN_12.

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //Enable PORTA clock                    

RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE); //Enable CAN1 clock

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;

GPIO_InitStructure.GPIO_Speed ​​= GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//Multiplex push-pull

GPIO_Init(GPIOA, &GPIO_InitStructure);// Initialize IO

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//Pull up input

GPIO_Init(GPIOA, &GPIO_InitStructure);// Initialize IO

After configuring GPIO, you need to configure the CAN bus

//CAN unit settings

CAN_InitStructure.CAN_TTCM=DISABLE;//Non-time triggered communication mode  

CAN_InitStructure.CAN_ABOM=ENABLE;//Automatic offline management of software 

CAN_InitStructure.CAN_AWUM=DISABLE;//Sleep mode wakeup by software (clear the SLEEP bit of CAN->MCR)

CAN_InitStructure.CAN_NART=ENABLE;// Disable automatic message transmission 

CAN_InitStructure.CAN_RFLM=DISABLE; //The message is not locked, the new one overwrites the old one  

CAN_InitStructure.CAN_TXFP=DISABLE;//The priority is determined by the message identifier 

CAN_InitStructure.CAN_Mode= mode;        //Mode setting: mode:0, normal mode; 1, loopback mode; 

//Set the baud rate

CAN_InitStructure.CAN_SJW=tsjw;//Resynchronization jump width (Tsjw) is tsjw+1 time unit  

CAN_InitStructure.CAN_BS1=tbs1;//Tbs1=tbs1+1 time unit

CAN_InitStructure.CAN_BS2=tbs2;//Tbs2=tbs2+1 time unit

CAN_InitStructure.CAN_Prescaler=brp; //Frequency division factor (Fdiv) is brp+1

CAN_Init(CAN1, &CAN_InitStructure);        //Initialize CAN1 

The CAN bus also needs to configure the receiving ID and filter

CAN_FilterInitStructure.CAN_FilterNumber=0;//Filter 0

CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask;// Mask bit pattern

CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit;//32 bits wide 

CAN_FilterInitStructure.CAN_FilterIdHigh=0x0000;//32-bit ID

CAN_FilterInitStructure.CAN_FilterIdLow=0x0000;

CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0x0000;//32-bit MASK

CAN_FilterInitStructure.CAN_FilterMaskIdLow=0x0000;

CAN_FilterInitStructure.CAN_FilterFIFOAssignment=CAN_Filter_FIFO0; //Filter 0 is associated with FIFO0

CAN_FilterInitStructure.CAN_FilterActivation=ENABLE; //Activate filter 0

CAN_FilterInit(&CAN_FilterInitStructure);// Initialize the filter

Finally, set up the CAN interrupt service

CAN_ITConfig(CAN1,CAN_IT_FMP0,ENABLE);//FIFO0 message registration interrupt is enabled.    

NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; // The main priority is 1

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; // The sub-priority is 0

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

I tested that the 1Mhz speed communication is fine. And the CAN bus will not get stuck even if the automatic offline management is turned on and the two pins are short-circuited.