serial.c

一种标准的PC AT键盘来提供大多数微控制器所需的某些人机接口方法

#include <stdio.h>
#include <pgmspace.h>
#include <io8515.h>             /* SFR declarations */

#include "serial.h"

#define ESC 0x1b
#define BUFF_SIZE 64

flash char CLR[] = {ESC, '[','H', ESC, '[', '2', 'J',0};

unsigned char UART_buffer[BUFF_SIZE];
unsigned char *inptr, *outptr;
unsigned char buff_cnt;


void init_uart(void)
{
    inptr =  UART_buffer;
    outptr = UART_buffer;
    buff_cnt = 0;
}

void clr(void)
{
    puts_P(CLR);                                // Send a 'clear screen' to a VT100 terminal
}

int putchar(int c)
{
    if (buff_cnt<BUFF_SIZE)
    {
        *inptr = c;                             // Put character into buffer
        inptr++;                                // Increment pointer
        
        buff_cnt++;
        
        if (inptr >= UART_buffer + BUFF_SIZE)   // Pointer wrapping
            inptr = UART_buffer;
 
        UCR = 0x28;                             // Enable UART Data register
                                                // empty interrupt
        
        return 1;
    } else {
        return 0;                               // Buffer is full
    }
        
}

// Interrupt driven transmitter

interrupt [UART_UDRE_vect] void UART_UDRE_interrupt(void)
{
    UDR = *outptr;                              // Send next byte
    outptr++;                                   // Increment pointer
    
    if (outptr >= UART_buffer + BUFF_SIZE)      // Pointer wrapping
        outptr = UART_buffer;

    if(--buff_cnt == 0)                         // If buffer is empty:
        UCR = UCR && (1<<UDRIE);                //    disabled interrupt
}