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本篇讲的单片机是第十一届蓝桥杯单片机实训的硬件设备。
<>蓝桥杯单片机硬件基础
<>PCF8591电路图：
PCF8591是具有IIC总线接口的8位A/D及D/A转换器，有4路A/D转换输入，1路D/A模拟输出，信息传输仅靠时钟线SCL和数据线SDA就可以实现。
<>模拟电压输入电路图：
硬件上旋动Rb2旋钮，即可改变模拟电压的输入值。
<>光强电阻电压输入电路图：
光敏电阻值的改变，影响该模拟电压通道的输入值。
<>ADC/DAC模块驱动配置
* PCF8591采用IIC总线接口器件寻址方法，器件地址和引脚地址如下：
可知写入的第一个字节为0x90；
* 控制字节格式配置如下：
因此，模拟电压控制字为0x43；光敏电阻电压输入控制字为0x41；
<>ADC/DAC模块函数代码：
由于均采用IIC总线接口，因此ADC/DAC转换函数与先前介绍的AT24C02存储器一致，只需要修改相应的器件地址和控制字即可，这里就不多介绍了。
<>相关代码编写：
* ADC读取函数 u8 ADC(u8 channal) { u8 dat; IIC_Start(); IIC_SendByte(0x90);
IIC_WaitAck(); IIC_SendByte(0x40+ch); IIC_WaitAck(); IIC_Start(); IIC_SendByte(
0x91); IIC_WaitAck(); dat = IIC_RecByte(); IIC_SendAck(1); //不应答 IIC_Stop();
return dat; }
* DAC输出函数(电压输出) void DAC(u8 dat) { IIC_Start(); IIC_SendByte(0x90);
IIC_WaitAck(); IIC_SendByte(0x43); IIC_WaitAck(); IIC_SendByte(dat); IIC_WaitAck
(); IIC_Stop(); Delay5ms(); }
函数的使用方法，这里就不展示了，欢迎提问和咨询 ~
