RS-485单片机通讯模块原理图PCB工程及源码等全套资料下载 -

/********************************************************************
汇诚科技
实现功能:RS-485单片机通讯模块_测试程序自动返回
使用芯片：AT89S52
晶振：11.0592MHZ
波特率：9600
编译环境：Keil
作者：zhangxinchun
【声明】此程序仅用于学习与参考，引用请注明版权和作者信息！
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#include "reg51.h"
#include "intrins.h"
typedef unsigned char BYTE;
typedef unsigned int WORD;
#define FOSC 11059200L //System frequency
#define BAUD 9600 //UART baudrate
/*Define UART parity mode*/
#define NONE_PARITY 0 //None parity
#define ODD_PARITY 1 //Odd parity
#define EVEN_PARITY 2 //Even parity
#define MARK_PARITY 3 //Mark parity
#define SPACE_PARITY 4 //Space parity
#define PARITYBIT EVEN_PARITY //Testing even parity
sbit bit9 = P2^2; //P2.2 show UART data bit9
bit busy;
void SendData(BYTE dat);
void SendString(char *s);
void main()
{
#if (PARITYBIT == NONE_PARITY)
SCON = 0x50; //8-bit variable UART
#elif (PARITYBIT == ODD_PARITY) || (PARITYBIT == EVEN_PARITY) || (PARITYBIT == MARK_PARITY)
SCON = 0xda; //9-bit variable UART, parity bit initial to 1
#elif (PARITYBIT == SPACE_PARITY)
SCON = 0xd2; //9-bit variable UART, parity bit initial to 0
#endif
TMOD = 0x20; //Set Timer1 as 8-bit auto reload mode
TH1 = TL1 = -(FOSC/12/32/BAUD); //Set auto-reload vaule
TR1 = 1; //Timer1 start run
ES = 1; //Enable UART interrupt
EA = 1; //Open master interrupt switch
SendString("AT89S52 11.0592MHZ 9600 ");
while(1);
}
/*----------------------------
UART interrupt service routine
----------------------------*/
void Uart_Isr() interrupt 4 using 1
{
if (RI)
{
RI = 0; //Clear receive interrupt flag
P0 = SBUF; //P0 show UART data
bit9 = RB8; //P2.2 show parity bit
}
if (TI)
{
TI = 0; //Clear transmit interrupt flag
busy = 0; //Clear transmit busy flag
}
}
/*----------------------------
Send a byte data to UART
Input: dat (data to be sent)
Output:None
----------------------------*/
void SendData(BYTE dat)
{
while (busy); //Wait for the completion of the previous data is sent
ACC = dat; //Calculate the even parity bit P (PSW.0)
if (P) //Set the parity bit according to P
{
#if (PARITYBIT == ODD_PARITY)
TB8 = 0; //Set parity bit to 0
#elif (PARITYBIT == EVEN_PARITY)
TB8 = 1; //Set parity bit to 1
#endif
}
else
{
#if (PARITYBIT == ODD_PARITY)
TB8 = 1; //Set parity bit to 1
#elif (PARITYBIT == EVEN_PARITY)
TB8 = 0; //Set parity bit to 0
#endif
}
busy = 1;
SBUF = ACC; //Send data to UART buffer
}
/*----------------------------
Send a string to UART
Input: s (address of string)
Output:None
----------------------------*/
void SendString(char *s)
{
while (*s) //Check the end of the string
{
SendData(*s++); //Send current char and increment string ptr
}
}
/********************************************************************
结束
*********************************************************************/

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