C51: Transmitting data via serial port interruption-EEWORLD

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1. Serial port mode, baud rate setting:

1.1 T1 working mode 2, automatic reload 8-bit counting mode, as baud rate generator, baud rate calculation:

1.1 Baud rate calculation:

Baud rate = 2^SMOD * T1 overflow rate / 32

T1 overflow rate = f/(12*(256-TH1))

Result: Baud rate = 2^SMOD * f/32 * 1/[12*(256-TH1)]

For example: f=11.0592, SMOD=0, baud rate=9600, then: TH1=0xfd.

1.2 T1 working mode 2 (timer T1 interrupt disabled) setting:

TMOD=0x20;

TR1=1;

1.3 Serial port mode 1, allow receiving settings

SCON = 0x50;

If you use printf() to send data from the serial port, you must set TI=1.

2. Serial port interrupt setting

2.1 Open the general interrupt, EA=1;

2.2 Enable serial port interrupt, ES=1;

Programming features:

1. The serial port uses interrupt mode: after receiving a character, it sends the character immediately.

#include "reg52.h"

#define uchar unsigned char

uchar mybuf;

//Declare the serial port initialization function

void init();

void main()

{

init();

//Open interrupt

EA=1;

ES=1;

while(1);

}

//Serial port interrupt response function

void serial() interrupt 4

{

//Disable interrupt

ES=0;

//Serial port receives characters

if(RI==1)

{

RI=0;

mybuf=SBUF;

SBUF=mybuf;

while(TI==0);

TI=0;

}

//Open interrupt

ES=1;

}

//Serial port initialization

void init()

{

//T1 mode 2 as baud rate,

TMOD=0x20;

//Serial port mode 1, allow receiving settings

SCON=0x50;

//f=11.0592,baud=9600,calculate constant

TH1=0xfd;

TL1=0xfd;

//start up

TR1=1;

}

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