stm32与三个stc89c52进行CAN通信程序

要实现STM32与三个STC89C52之间的CAN通信，需要先了解CAN总线的基本概念和协议，然后编写相应的程序来实现通信。

以下是一个简单的CAN通信程序，其中STM32作为CAN总线的主控，负责发送数据，STC89C52作为从设备，负责接收数据。

STM32代码：

#include "stm32f10x.h"
#include "stm32f10x_can.h"

int main(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    CAN_InitTypeDef CAN_InitStructure;
    CAN_FilterInitTypeDef CAN_FilterInitStructure;
    uint8_t data[8] = {0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF};

    // 初始化GPIO
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // 初始化CAN
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
    CAN_StructInit(&CAN_InitStructure);
    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_Normal;
    CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
    CAN_InitStructure.CAN_BS1 = CAN_BS1_6tq;
    CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
    CAN_InitStructure.CAN_Prescaler = 4;
    CAN_Init(CAN1, &CAN_InitStructure);

    // 初始化CAN过滤器
    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);

    // 发送数据
    CAN_Transmit(CAN1, &data, 0x123, CAN_RTR_Data);

    while(1);
}

STC89C52代码：

#include <reg52.h>
#include <intrins.h>

#define uchar unsigned char
#define uint unsigned int

sbit P3_5 = P3^5; // CAN发送引脚
sbit P3_6 = P3^6; // CAN接收引脚

void CAN_Init()
{
    P3_5 = 0;
    P3_6 = 1;
}

void CAN_SendData(uchar *data)
{
    int i;
    CAN_Init();
    for(i=0; i<8; i++)
    {
        P3_5 = 0;
        _nop_();
        _nop_();
        if(data[i])
            P3_6 = 1;
        else
            P3_6 = 0;
        _nop_();
        _nop_();
        P3_5 = 1;
        _nop_();
        _nop_();
        P3_5 = 0;
        _nop_();
        _nop_();
        P3_6 = 0;
    }
}

void main()
{
    uchar data[8];
    while(1)
    {
        if(P3_7 == 0)
        {
            // 接收到CAN数据
            int i;
            for(i=0; i<8; i++)
            {
                _nop_();
                _nop_();
                data[i] = P3_6;
                _nop_();
                _nop_();
                P3_5 = 1;
                _nop_();
                _nop_();
                P3_5 = 0;
            }
            // 处理接收到的数据
        }
    }
}

在以上程序中，STM32通过CAN总线发送数据，STC89C52通过CAN总线接收数据，并处理接收到的数据。要实现三个STC89C52之间的通信，则需要在每个STC89C52上都运行类似的接收程序。