许久没有学新东西，整一下Max6675吧

MCU用了STC15W408，串口输出

#include "stc15.h"
#include "intrins.h"

typedef unsigned char BYTE;
typedef unsigned int WORD;

#define FOSC 11059200L          //系统频率
#define BAUD 115200             //串口波特率

#define NONE_PARITY     0       //无校验
#define ODD_PARITY      1       //奇校验
#define EVEN_PARITY     2       //偶校验
#define MARK_PARITY     3       //标记校验
#define SPACE_PARITY    4       //空白校验

#define PARITYBIT NONE_PARITY   //定义校验位



#define S1_S0 0x40              //P_SW1.6
#define S1_S1 0x80              //P_SW1.7


bit busy;

unsigned int temp_k = 0;
sbit spi_cs_pin = P1^7;
sbit spi_dat_pin = P1^6;
sbit spi_sck_pin = P1^5;


void SendData(BYTE dat);
void SendString(char *s);

#define DLY_SET 100
void delay(unsigned long i)
{
    while(i--);
}

void delay_l(unsigned long i)
{
    while(i--);
}


void main()
{

    unsigned char spi_rcv_cnt = 0;

    P1M0 = 0xa0;
    P1M1 = 0x00;

    P3M0 = 0x00;
    P3M1 = 0x00;

    P5M0 = 0x00;
    P5M1 = 0x00;


    ACC = P_SW1;
    ACC &= ~(S1_S0 | S1_S1);    //S1_S0=0 S1_S1=0
    P_SW1 = ACC;                //(P3.0/RxD, P3.1/TxD)
    
//  ACC = P_SW1;
//  ACC &= ~(S1_S0 | S1_S1);    //S1_S0=1 S1_S1=0
//  ACC |= S1_S0;               //(P3.6/RxD_2, P3.7/TxD_2)
//  P_SW1 = ACC;  
//  
//  ACC = P_SW1;
//  ACC &= ~(S1_S0 | S1_S1);    //S1_S0=0 S1_S1=1
//  ACC |= S1_S1;               //(P1.6/RxD_3, P1.7/TxD_3)
//  P_SW1 = ACC;  

#if (PARITYBIT == NONE_PARITY)
    SCON = 0x50;                //8位可变波特率
#elif (PARITYBIT == ODD_PARITY) || (PARITYBIT == EVEN_PARITY) || (PARITYBIT == MARK_PARITY)
    SCON = 0xda;                //9位可变波特率,校验位初始为1
#elif (PARITYBIT == SPACE_PARITY)
    SCON = 0xd2;                //9位可变波特率,校验位初始为0
#endif

    T2L = (65536 - (FOSC/4/BAUD));   //设置波特率重装值
    T2H = (65536 - (FOSC/4/BAUD))>>8;
    AUXR = 0x14;                //T2为1T模式, 并启动定时器2
    AUXR |= 0x01;               //选择定时器2为串口1的波特率发生器
    ES = 1;                     //使能串口1中断
    EA = 1;

    SendString("Sys boot ... \r\n");
    while(1)
    {
        delay_l(100000);
        spi_sck_pin = 0;
        
        spi_cs_pin = 0;

        delay(DLY_SET);
        
        temp_k = 0;

        for(spi_rcv_cnt = 0;spi_rcv_cnt < 16;spi_rcv_cnt ++)
        {
            temp_k <<= 1;
            spi_sck_pin = 0;
            delay(DLY_SET);
            spi_sck_pin = 1;
            delay(DLY_SET);

            if(spi_dat_pin == 0)
            {
                // temp_k &= 0xfffe;
            }
			else
			{
				temp_k |= 0x00001;
			}

            // spi_sck_pin = 0;
        }
        spi_sck_pin = 0;
        spi_cs_pin = 1;

        if(temp_k & 0x04)
        {
            P10 = 1;   
            // SendString("Sensor disconncted ... \r\n");
        }
        else
        {
            P10 = 0;
            // SendString("Sensor connected ... \r\n");
        }

        temp_k >>= 5;

        temp_k -= 5;
        
        SendString("Temp: ");
        SendData(temp_k/100+0x30);
        SendData(temp_k%100/10+0x30);
        SendData(temp_k%100%10+0x30);
        SendString("\n\r");

    }
}

/*----------------------------
UART 中断服务程序
-----------------------------*/
void Uart() interrupt 4
{
    if (RI)
    {
        RI = 0;                 //清除RI位
        P0 = SBUF;              //P0显示串口数据
        P22 = RB8;              //P2.2显示校验位
    }
    if (TI)
    {
        TI = 0;                 //清除TI位
        busy = 0;               //清忙标志
    }
}

/*----------------------------
发送串口数据
----------------------------*/
void SendData(BYTE dat)
{
    while (busy);               //等待前面的数据发送完成
    ACC = dat;                  //获取校验位P (PSW.0)
    if (P)                      //根据P来设置校验位
    {
#if (PARITYBIT == ODD_PARITY)
        TB8 = 0;                //设置校验位为0
#elif (PARITYBIT == EVEN_PARITY)
        TB8 = 1;                //设置校验位为1
#endif
    }
    else
    {
#if (PARITYBIT == ODD_PARITY)
        TB8 = 1;                //设置校验位为1
#elif (PARITYBIT == EVEN_PARITY)
        TB8 = 0;                //设置校验位为0
#endif
    }
    busy = 1;
    SBUF = ACC;                 //写数据到UART数据寄存器
}

/*----------------------------
发送字符串
----------------------------*/
void SendString(char *s)
{
    while (*s)                  //检测字符串结束标志
    {
        SendData(*s++);         //发送当前字符
    }
}

偷懒，直接用了阻塞式延时delay。。。

去掉了小数部分

采样需要时间

CS置高后6675更新数据

断开热电偶时P10置高，LED熄灭

MAX6675小模块测量值比万用表测量值高6摄氏度左右，直接测量值减去6作为输出值

采用打火机加热铠装热电偶，才500度不到就发红了，测试完毕！

Over！