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[/] [cpu_lecture/] [trunk/] [app/] [hello.c] - Blame information for rev 2

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1 2 jsauermann 
#include "stdint.h"
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#include "avr/io.h"
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#include "avr/pgmspace.h"
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#undef F_CPU
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#define F_CPU 25000000UL
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#include "util/delay.h"
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     //----------------------------------------------------------------------//
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    //                                                                      //
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   //   print char cc on UART.                                             //
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  //    return number of chars printed (i.e. 1).                          //
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 //                                                                      //
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//----------------------------------------------------------------------//
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uint8_t
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uart_putc(uint8_t cc)
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{
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    while ((UCSRA & (1 << UDRE)) == 0)      ;
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    UDR = cc;
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    return 1;
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}
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     //----------------------------------------------------------------------//
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    //                                                                      //
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   //   print char cc on 7 segment display.                                //
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  //    return number of chars printed (i.e. 1).                          //
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 //                                                                      //
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//----------------------------------------------------------------------//
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// The segments of the display are encoded like this:
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//
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//
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//      segment     PORT B
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//      name        Bit number
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//      ----A----   ----0----
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//      |       |   |       |
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//      F       B   5       1
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//      |       |   |       |
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//      ----G----   ----6----
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//      |       |   |       |
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//      E       C   4       2
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//      |       |   |       |
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//      ----D----   ----3----
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//
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//-----------------------------------------------------------------------------
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#define SEG7(G, F, E, D, C, B, A)   (~(G<<6|F<<5|E<<4|D<<3|C<<2|B<<1|A))
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uint8_t
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seg7_putc(uint8_t cc)
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{
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uint16_t t;
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    switch(cc)
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    {                   //   G F E D C B A
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    case ' ':   PORTB = SEG7(0,0,0,0,0,0,0);        break;
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    case 'E':   PORTB = SEG7(1,1,1,1,0,0,1);        break;
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    case 'H':   PORTB = SEG7(1,1,1,0,1,1,0);        break;
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    case 'L':   PORTB = SEG7(0,1,1,1,0,0,0);        break;
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    case 'O':   PORTB = SEG7(0,1,1,1,1,1,1);        break;
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    default:    PORTB = SEG7(1,0,0,1,0,0,1);        break;
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    }
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    // wait 800 + 200 ms. This can be quite boring in simulations,
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    // so we wait only if DIP switch 6 is closed.
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    //
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    if (!(PINB & 0x20))     for (t = 0; t < 800; ++t)   _delay_ms(1);
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    PORTB = SEG7(0,0,0,0,0,0,0);
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    if (!(PINB & 0x20))     for (t = 0; t < 200; ++t)   _delay_ms(1);
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    return 1;
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}
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     //----------------------------------------------------------------------//
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    //                                                                      //
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   //   print string s on UART.                                            //
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  //    return number of chars printed.                                   //
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 //                                                                      //
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//----------------------------------------------------------------------//
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uint16_t
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uart_puts(const char * s)
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{
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const char * from = s;
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uint8_t cc;
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    while ((cc = pgm_read_byte(s++)))   uart_putc(cc);
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    return s - from - 1;
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}
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     //----------------------------------------------------------------------//
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    //                                                                      //
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   //   print string s on 7 segment display.                               //
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  //    return number of chars printed.                                   //
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 //                                                                      //
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//----------------------------------------------------------------------//
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uint16_t
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seg7_puts(const char * s)
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{
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const char * from = s;
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uint8_t cc;
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    while ((cc = pgm_read_byte(s++)))   seg7_putc(cc);
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    return s - from - 1;
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}
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//-----------------------------------------------------------------------------
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int
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main(int argc, char * argv[])
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{
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    for (;;)
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    {
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        if (PINB & 0x40)    // DIP switch 7 open.
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            {
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                // print 'Hello world' on UART.
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                uart_puts(PSTR("Hello, World!\r\n"));
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            }
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        else                // DIP switch 7 closed.
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            {
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                // print 'HELLO' on 7-segment display
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                seg7_puts(PSTR("HELLO "));
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            }
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    }
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}
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//-----------------------------------------------------------------------------

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