既然定時要求高當然要用定時器，在中斷代碼中發串口數據
#include "reg51.h"
#include "intrins.h"
sfr T2CON = 0xC8; //timer2 control register
sfr RCAP2L = 0xCA;
sfr RCAP2H = 0xCB;
sfr TL2 = 0xCC;
sfr TH2 = 0xCD;
typedef unsigned char BYTE;
typedef unsigned int WORD;
#define FOSC 18432000L //System frequency
#define BAUD 115200 //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
TL2 = RCAP2L = (65536-(FOSC/32/BAUD)); //Set auto-reload vaule
TH2 = RCAP2H = (65536-(FOSC/32/BAUD)) >> 8;
T2CON = 0x34; //Timer2 start run
ES = 1; //Enable UART interrupt
EA = 1; //Open master interrupt switch
SendString("STC89-90xx\r\nUart Test !\r\n");
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
}
}
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