git.zerfleddert.de Git - rsbs2/blob - bmc/usart.c

   1 #include <avr/io.h>
   2 #include <stdio.h>
   3
   4 #include "config.h"
   5 #include "usart.h"
   6
   7 #ifdef DEBUG
   8
   9 #define UBRR_VAL ((F_CPU+BAUD*8)/(BAUD*16)-1)
  10 #define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1)))
  11 #define BAUD_ERROR ((BAUD_REAL*1000)/BAUD)
  12
  13 #if ((BAUD_ERROR<990) || (BAUD_ERROR>1010))
  14 #error Systematischer Fehler der Baudrate grösser 1% und damit zu hoch!
  15 #endif
  16
  17 int usart_put(char c, FILE *stream)
  18 {
  19         if (c == '\n')
  20                 usart_put('\r', stream);
  21
  22         while(!(UCSRA & (1<<UDRE))) {}
  23         UDR = c;
  24         return 0;
  25 }
  26
  27 static FILE usart_stdout = FDEV_SETUP_STREAM(usart_put, NULL, _FDEV_SETUP_WRITE);
  28 #endif
  29
  30 void usart_init()
  31 {
  32 #ifdef DEBUG
  33         UCSRB |= (1<<TXEN);
  34         UCSRC |= (1<<URSEL)|(1 << UCSZ1)|(1 << UCSZ0);
  35
  36         UBRRH = UBRR_VAL >> 8;
  37         UBRRL = UBRR_VAL & 0xFF;
  38
  39         stdout = &usart_stdout;
  40 #endif
  41 }