基于mikroC和microchip的TC74的温度测量方案

三、电路图

我在这里用的是芯片PIC18F2550，它可以与任何其他规模较小的PIC微控制器实现I2C通信。温度由TC74传感器读取并显示在LCD字符。别忘 了把两个上拉电阻（1K）连接在SDA和SCL线I2C总线上。在本实验中采用PIC18F2550单片机PIC板来自于StartUSB for PIC board.。

图4 电路图

图5 实物图

图6 TC74温度传感器

四、软件

PIC18F2550固件是在C使用MikroC Pro for PIC编译开发的。MikroC Pro for PIC编译器提供的内置支持I2C库。单片机读取TC74内部温度寄存器温度字并显示在LCD。下面的程序显示，TC74的整个工作范围内在40 至125°C。

程序：

/* Project: Using TC74 with PIC microcontroller

for temperature measurement

MCU: PIC18F2550 on-board StartUSB for PIC

Clock 48.0 MHz using HS + PLL

MCLR Enabled

*/

// Define LCD module connections.

sbit LCD_RS at RC6_bit;

sbit LCD_EN at RC7_bit;

sbit LCD_D4 at RB4_bit;

sbit LCD_D5 at RB5_bit;

sbit LCD_D6 at RB6_bit;

sbit LCD_D7 at RB7_bit;

sbit LCD_RS_Direction at TRISC6_bit;

sbit LCD_EN_Direction at TRISC7_bit;

sbit LCD_D4_Direction at TRISB4_bit;

sbit LCD_D5_Direction at TRISB5_bit;

sbit LCD_D6_Direction at TRISB6_bit;

sbit LCD_D7_Direction at TRISB7_bit;

// End LCD module connection definition

unsigned char Temp;

unsigned short num;

const int TC74A0 = 0x90;

void check_device(unsigned short dev_address){ I2C1_Start();

if (I2C1_Wr(dev_address)){ Lcd_Out(1,1,"Device not found");

}

else Lcd_Out(1,1,"TC74 device");

I2C1_Stop();

}

unsigned short Read_Temp(){

unsigned short result; I2C1_Start(); // Issue start signal

I2C1_Wr(TC74A0); // Address + Write bit

I2C1_Wr(0x00); // Read Temp

I2C1_Repeated_Start(); // Issue start signal

I2C1_Wr(TC74A0+1); // Address + Read bit

result = I2C1_Rd(0u); return result;

}