/* 877_15seg_2disp.c.c
 *
 * Copyright (c) 2002, 2003 Bruce Kroeze
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * ---------------------------------
 *
 * Displays characters on a pair of 15 seg led module
 *
 * Revisions:
 * 22 Dec 2002 - Initial Version
 * 25 Dec 2002 - Added ring buffer
 *
 * Hardware:
 * 16F877 at 20Mhz
 * PCF8574P I2C IO Expander (IO1)
 * PCF8574P I2C IO Expander (IO2)
 * 2 LTP588G displays connected on a bus with:
 * IO1 P0-P8: ABCDEFGH
 * IO2 P0-P7: IJKLMNO
 *
 * V+ for the displays wired through a 2907A transistor:
 * LED0: RB7
 * LED1: RB6
 */

#include "defs_877.h"
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(CLOCK=20000000)
#use fast_io(b)
#include "15seg.h"
#use rs232(baud=9600, PARITY=N, BITS=8, xmit=PIN_C7, rcv=PIN_C6)
#use i2c(master, sda=PIN_C4, scl=PIN_C3, FORCE_HW)

int8 displayIx = 1;
char display_chars[] = {'\0', '\0'};

#define MAX_RING_SIZE 2
#include "ring_buffer.c"
#define clear15 ring_clear

#DEFINE IO1 0b01000000
#DEFINE IO2 0b01000010

int8 clock=100;

void write_i2c_byte(int8 addr, int8 data)
{
  i2c_start();
  i2c_write(addr);
  i2c_write(data);
  i2c_stop();
}

void display_segs(int16 ch)
{
  write_i2c_byte(IO1, ch ^ 0xFF);
  write_i2c_byte(IO2, (ch >> 8) ^ 0xFF);
}

inline void print_ch(char ch)
{
  display_segs(get_15seg(ch));
}

void display_current()
{
  if (displayIx == 0) {
    print_ch(display_chars[0]);
    PORTB = 0b01111111;
    displayIx = 1;
  } else {
    print_ch(display_chars[1]);
    PORTB = 0b10111111;
    displayIx = 0;
  }
}

void print15(char ch)
{
  ring_append(ch);

  display_chars[0] = ring_peek(0);
  display_chars[1] = ring_peek(1);

  if (display_chars[1] != 0)
    inc_ring_read_ix();

  printf("%c%c\n\r", display_chars[0],display_chars[1]);
}

#int_rtcc
void rtc_handler()
{
  // hits at 5Khz == 200 uSec
  // dividing by 50 gives us 100hz
  --clock;
  if (clock == 0) {
    display_current();
    clock = 50;
  }

  enable_interrupts(INT_RTCC);
}

void main()
{
  char curr;
  setup_psp(PSP_DISABLED);
  setup_timer_0(RTCC_INTERNAL | RTCC_DIV_4);
  TRISB = 0; // all output
  PORTB = 0xFF;
  clear15();
  
  printf("Ready to display 2.\n\r");
  getch();
  enable_interrupts(INT_RTCC);
  enable_interrupts(GLOBAL);

  while (1) {
    curr = getch();  
    printf("%c = %X\n\r", curr, curr);
    print15(curr);
  }
}