单片机 RS485 通信实验.doc

单片机 RS485 通信实验/发送方的程序 #include c8051f020.h #include /*函数声明*/void SYSCLK_Init (void); /*单片机时钟初始化void PORT_Init (void); / 初始化IO口void Uart0_Init(void); /串口0 初始化/* 变量及I/O口定义 *unsigned char data aaa5_at_ 0x30; unsigned char data BBB5_at_ 0x40; unsigned char data EEE _at_ 0x50; int k; /*单片机时钟初始化*/void SYSCLK_Init (void) int i; / delay counter OSCXCN = 0x65; / start external oscillator with / 18.432MHz crystal for (i=0; i 256; i+) ; / Wait for osc. to start up while (!(OSCXCN & 0x80) ; / Wait for crystal osc. to settle OSCICN = 0x88; / select external oscillator as SYSCLK / source and enable missing clock / detector/*/初始化IO口*/void PORT_Init (void) XBR0 = 0x07; / Enable SMBus, SPI0, and UART0 XBR1= 0x02; /交叉开关允许XBR2 = 0x40; / Enable crossbar and weak P74OUT=0x04 ;/pull-ups /*串口0 初始化*/ void Uart0_Init(void) TMOD = 0x20; / TMOD: 定时器1, 模式2, 8位重载 SCON0 = 0x40; / SCON0: 模式1, 8位UART, PCON = 0x80; / SMOD00 = 1 TH1= 0x70; TL1= 0x70; CKCON=0x10; / T1时钟为系统时钟12分频 TR1=1; /计数器1开始计时, 打开串口Uart0 /*主程序*/void main (void) WDTCN = 0xde;WDTCN = 0xad; /关看门狗 SYSCLK_Init (); /初始化时钟 PORT_Init (); /初始化IO口 Uart0_Init(); /串口0 初始化 aaa0=0x01a; aaa1=0x02b; aaa2=0x03c; aaa3=0x04d; aaa4=0x05e; aaa5=0x06f; P5=0x40;/485发送 for(k=0;k=5;k+) SBUF0=aaak; while(TI0!=1); TI0=0; P5=0x0;/485接收 REN0=1; for(k=0;k=5;k+) while(RI0!=1); RI0=0; BBBk=SBUF0 ; while(1) ; /接收方的程序#include c8051f020.h #include /*函数声明*/void SYSCLK_Init (void); /*单片机时钟初始化void PORT_Init (void); / 初始化IO口void Uart0_Init(void); /串口0 初始化/* 变量及I/O口定义 *unsigned char data aaa5_at_ 0x30; unsigned char data BBB5_at_ 0x40; unsigned char data EEE _at_ 0x50; int k;int i,j; /*单片机时钟初始化*/void SYSCLK_Init (void) int i; / delay counter OSCXCN = 0x65; / start external oscillator with / 18.432MHz crystal for (i=0; i 256; i+) ; / Wait for osc. to start up while (!(OSCXCN & 0x80) ; / Wait for crystal osc. to settle OSCICN = 0x88; / select external oscillator as SYSCLK / source and enable missing clock / detector/*/初始化IO口*/void PORT_Init (void) XBR0 = 0x07; / Enable SMBus, SPI0, and UART0 XBR1= 0x02; /交叉开关允许XBR2 = 0x40; / Enable crossbar and weak P74OUT=0x04 ;/pull-ups; /*串口0 初始化*/ void Uart0_Init(void) TMOD = 0x20; / TMOD: 定时器1, 模式2, 8位重载 SCON0 = 0x40; / SCON0: 模式1, 8位UART, PCON = 0x80; / SMOD00 = 1 TH1= 0x70; TL1= 0x70; CKCON=0x10; / T1时钟为系统时钟12分频 TR1=1; /计数器1开始计时, 打开串口Uart0 /*主程序*/void main (void) WDTCN = 0xde;WDTCN = 0xad; /关看门狗 SYSCLK_Init (); /初始化时钟 PORT_Init (); /初始化IO口 Uart0_Init(); /串口0 初始化 aaa0=0x021; aaa1=0x022; aaa2=0x023; aaa3=0x024; aaa4=0x025; aaa5=0x026; P5=0x0;/485接收 REN0=1; for(k=0;k=5;k+) while(RI0!=1); RI0=0; BBBk=S