查看“使用PCF8574扩展C8051F的I/O端口”的源代码


<table border="0" cellpadding="0" cellspacing="0" style="color: rgb(72, 61, 139); font-family: Arial, 新宋体, 微软雅黑; font-size: 12px;" width="780"><tbody><tr><th class="type_483D8B" scope="col" style="line-height: 20px; font-weight: normal; border-top-style: none;" valign="top">
<table border="0" cellpadding="0" cellspacing="0" width="120"><tbody><tr><th bgcolor="#698192" class="white_12px_b" height="20" scope="col" style="font-size: 12px; color: rgb(255, 255, 255); line-height: 20px; font-family: Arial, Helvetica, sans-serif;">系统功能</th></tr></tbody></table>
　　 使用PCF8574扩展C8051F的I/O端口。


</th></tr><tr><th class="type_483D8B" scope="col" style="line-height: 20px; font-weight: normal; border-top-style: none;" valign="top">
<table border="0" cellpadding="0" cellspacing="0" width="120"><tbody><tr><th bgcolor="#698192" class="white_12px_b" height="20" scope="col" style="font-size: 12px; color: rgb(255, 255, 255); line-height: 20px; font-family: Arial, Helvetica, sans-serif;">硬件设计</th></tr></tbody></table>

[[File:C8051F_3_4.jpg]]
使用PCF8574扩展C8051F的I/O端口电路原理图


</th></tr><tr><th class="type_483D8B" scope="col" style="line-height: 20px; font-weight: normal; border-top-style: none;" valign="top">
<table border="0" cellpadding="0" cellspacing="0" width="120"><tbody><tr><th bgcolor="#698192" class="white_12px_b" height="20" scope="col" style="font-size: 12px; color: rgb(255, 255, 255); line-height: 20px; font-family: Arial, Helvetica, sans-serif;">软件设计</th></tr></tbody></table>
下面部分从TXT拷出，拷到网页，代码部分缺省了很多空格，比较凌乱，请谅解！
I2C(SMBus)详细程序请查看<a class="Blue_2_12px_" href="https://{{SERVERNAME}}/article/C8051F-4-3-4.htm" style="color: rgb(7, 66, 184);" target="_blank">C8051F I2C(SMBus)程序
。 

//目标系统: 基于C8051F单片机
//应用软件: Silicon IDE / Keil

/*01010101010101010101010101010101010101010101010101010101010101010101
----------------------------------------------------------------------
实验内容：
使用PCF8574的输出端口接上8位LED指示灯查看CPU输出到PCF8574的数据是否正常
----------------------------------------------------------------------
硬件连接：
将PCF8574的P0~P7口和8位LED指示灯相连。
DVK501(PCF8574PrlPort)    F320 EX
                           VCC    ---------   VCC
                           GND   ---------   GND
                           SDA    ---------   P1.0  
                           SCL    ---------   P1.1
----------------------------------------------------------------------
注意事项：
（1）若有加载库程序，请将光盘根目录下的“library”下的“C8051F”文件夹拷到D盘
（2）请详细阅读：光盘根目录下的“说明书首页.htm”里的相应产品说明
----------------------------------------------------------------------
10101010101010101010101010101010101010101010101010101010101010101010*/
#define _DVK501_F320_EX_
#include <c8051f320.h>
#include <../../../../library/C8051F/ws_clock.h>
#include <../../../../library/C8051F/ws_delay.h>
#include <../../../../library/C8051F/ws_iic_port.h>
#include <../../../../library/C8051F/ws_pcf8574.h>
void main(void)
{
uchar wRdat; // Test counter
//uchar *rDdat;
PCA0MD &amp;= ~0x40; // Clear watchdog timer enable
clock_external();	// Set oscillator in external,the clock is 12M
delay_ms(100);
Check_SDA(); 
XBR1 = 0x40; // Enable crossbar and weak pull-ups
SMBus_Init();
Enb_Interrupt(); 
wRdat = 0; // Output data counter
while (1)
{
/*Read_PCF8574(rDdat); // Read data
P2 = rDdat;*/
Write_PCF8574(wRdat);	// Write data
wRdat++;
delay_ms (500);
}
}
void Write_PCF8574(uchar Data)
{
SMBus_Write(0x40,Data,0,1);
}
void Read_PCF8574(uchar *Data)
{
SMBus_Read(0x41,Data,1);
}</th></tr><tr><th class="type_483D8B" scope="col" style="line-height: 20px; font-weight: normal; border-top-style: none;" valign="top">

<table border="0" cellpadding="0" cellspacing="0" width="120"><tbody><tr><th bgcolor="#698192" class="white_12px_b" height="20" scope="col" style="font-size: 12px; color: rgb(255, 255, 255); line-height: 20px; font-family: Arial, Helvetica, sans-serif;">系统调试</th></tr></tbody></table>
把PCF8574的输出端口的前4个端口接到VCC，后4个端口接到GND，连接P2与8位LED指示灯查看现象。</th></tr></tbody></table>