l_9_3_autobaud.c

来自「* Use 10 MHz crystal frequency. * Use 」· C语言 代码 · 共 60 行

#include "config.h"

#include "serial.c"
#include "serio.c"

// do autobaud detection
// prototypes
void autobuad(void);

// HSPLL mode, crystal = 7.3728 MHz 
// so Fosc = 29,491,200
char baud_rate[] = {191,95,47,31,15,7};

// enter carriage return repeatedly
// to set baud rate
void autobaud(void){
  char i,c,exit;

  i=0;
  serial_init(baud_rate[i],1);
  exit = 0;
  while(!exit) {
    // wait for character
    while (!RCIF);  // check RCIF bit 
    c = RCREG;
    if (FERR || OERR) {
      // baud rate too fast, reset
      i = 0;
      CREN = 0; // clear error
      CREN = 1;
    }
    if (c == 0x0D) { // found baud rate
      printf("Found baud rate."); pcrlf();
      exit = 1;
    } else {
      i++;
      if (i > 5) i = 0;  // try again
      serial_init(baud_rate[i],1);
    }
  }
}
  

// Try to automatically determine baud rate,
// then echo
void main(void)
{
  char c;
  autobaud();
  while(1){
    // do character echo
    c = getch();
    c++;
    putch(c);
  }
}