/* dro_simple 1 channel quadrature für avr-gcc auf 90s8515   */
/* Copyright (C) 2007 by Simon Schrödle       */
/* max 7219 led driver    */
/* 16 MHz */

#include <io.h>
#include <math.h>
#include <stdlib.h>
#include <interrupt.h>
#include <sig-avr.h>


typedef unsigned char  u08;
typedef unsigned short u16;

#define F_CPU   16000000      /* 16.00 MHz */

#define maxclk 0x01
#define maxdat 0x00
#define maxcs  0x02

#define debounce 5



#define brightx 0x0a
#define brighty 0x0a


signed long int acntx, acnty,acntz;
u08 merrorx,merrory,qinpx,qinpy,qinpz,test;

u08 cosy=0;

signed long int zerox[]={0,0,0,0,0,0,0,0,0,0};
signed long int zeroy[]={0,0,0,0,0,0,0,0,0,0};
signed long int zeroz[]={0,0,0,0,0,0,0,0,0,0};

signed char graytab[]={0,5,-5,0x10,
                          -5,0,0x10,5,
                          5,0x10,0,-5,
                          0x10,-5,5,0};
/*0x10: error, more than one bit changed */

SIGNAL (SIG_OVERFLOW0) /* sample with approx 62.5 khz */
{
   signed char delta;
   u08 ind;

   ind=inp(PINB);

     qinpx|=(ind&0x03)<<4; /* old state is still in bit 3,2 */
     qinpx>>=2; /* new state in bit 3,2; old state in bit 1,0 */
     delta=graytab[qinpx];
     if (delta==0x10)
     { delta=0;
       merrorx=0x80;  }
     acntx+=delta;

     qinpy|=(ind&0x0c)<<2; /* old state is still in bit 3,2 */
     qinpy>>=2; /* new state in bit 3,2; old state in bit 1,0 */
     delta=graytab[qinpy];
     if (delta==0x10)
     { delta=0;
       merrory=0x80;  }
     acnty+=delta;

   /*  qinpz|=(ind&0x30);
     qinpz>>=2;
     delta=graytab[qinpz];
     if (delta==0x10)
     { delta=0;
       merror|=merrorz;  }
     acntz+=delta;
*/
   /* outp(128,TCNT0); check duration of signal call! max 0xff clocks! */
}

u08 upc=0,downc=0;

void check_keyb(void)
{
  u08 ind;


  ind=inp(PINA);

/*reset to zero buttons*/
  if ((ind&1)==0) {zerox[cosy]=acntx; merrorx=0;merrory=0;}
  if ((ind&2)==0) {zeroy[cosy]=acnty; merrorx=0;merrory=0;}

/*  if (ind&4) {zeroz[cosy]=acntz;}
*/
/* cosy counter */
/*
  if (ind&8) {if (upc<=debounce) {upc++;}} else {upc=0;}
  if (ind&0x10) {if (downc<=debounce) {downc++;}} else {downc=0;}

  if ((upc==debounce)&&(cosy<9)) {cosy++;}
  if ((downc==debounce)&&(cosy>0)) {cosy--;}
*/
}

void dwrite(u16 dcx,u16 dcy) /* write single command to max */
{
  u08 i=16; /* clock 16 bits to 3x max7219 */

  sbi(PORTD,maxcs);
  cbi(PORTD,maxclk);
  cbi(PORTD,maxcs); /* CS LOW: start transmit */

  do {
/*    outp(merror,PORTD);*/

    if (dcy&0x8000) {sbi(PORTD,maxdat);} else {cbi(PORTD,maxdat);}
    dcy<<=1;
    sbi(PORTD,maxclk); /*CLOCK*/
    cbi(PORTD,maxclk); /*CLOCK LOW*/
  } while (--i);

  i=16;
  do {
/*    outp(merror,PORTD);*/

    if (dcx&0x8000) {sbi(PORTD,maxdat);} else {cbi(PORTD,maxdat);}
    dcx<<=1;
    sbi(PORTD,maxclk); /*CLOCK*/
    cbi(PORTD,maxclk); /*CLOCK LOW*/
  } while (--i);

  sbi(PORTD,maxcs); /*CS HI: load into latch*/
}

void init_leds(void)
{
  dwrite(0xf00,0xf00); /*test off*/
  dwrite(0x9ff,0x9ff); /*decode on*/
  dwrite(0xb06,0xb06); /*7 digits (incl sign) -999.999 to +999.999*/
  dwrite(0xc01,0xc01); /*display on*/
  dwrite(0xa00|brightx,0xa00|brighty); /*brightness*/
}

void write_leds(void)
{
  u08 i,x,y,z,mx,my,mz,sumx,sumy;
  unsigned long int signx,signy;
  unsigned long int digi,d;
  signed long int xd,yd,zd;

  xd=acntx-zerox[cosy];
  yd=acnty-zeroy[cosy];

/*  xd=3;
  yd=54;
*/
  signx=0x0700; /*blank sign */
  signy=0x0700;
  if (xd<0) {xd=-xd;signx=0x0702;} /* signs in mx,my,mz */
  if (yd<0) {yd=-yd;signy=0x0702;}
  dwrite(signx|merrorx,signy|merrory);

  d=100000;
  sumx=0;
  sumy=0;

  for (i=1;i<7;i++)
   { digi=i<<8;
     x=xd/d; xd=xd%d;
     y=yd/d; yd=yd%d;
     d=d/10;
     sumx+=x; /*leading zero supression */
     sumy+=y;

    if (i<3) {
     if (sumx==0) {x=0x0f;}
     if (sumy==0) {y=0x0f;}
    }
    if (i==3) {x|=0x80;y|=0x80;} /* decimal point */

     dwrite(digi|x,digi|y);
   }  /*write data */
   

  /*dwrite(0x0101,0x0106);
  dwrite(0x0202,0x0205);
  dwrite(0x0303,0x0304);
  dwrite(0x0404,0x0403);
  dwrite(0x0505,0x0502);
  dwrite(0x0606,0x0601);*/

}


int main(void)
{
   u08 ind;

   cli();
   outp(0x00,DDRB);
                       /* B:
                       bit 0..1,2..3,4..5 phase a/b input
                       bit 6..7 NC */
   outp(0xff,PORTB);

   outp(0x00,DDRA);
   outp(0xff,PORTA); /* A: inputs 0..2 reset x,y,z (or keypad 0..5 3x3 matrix)*/
                     /* bit 3,4 cosys up-down */

   outp(0xff,DDRD);  /* bit 0 DATA, 1 CLK, 2 CS  MAX7219  567 error xyz*/
   outp(0x00,PORTD);

   sbi(TIMSK,TOIE0); /* Enable TCNT0 overflow */
   outp(128,TCNT0); /* Reset Counter */

   outp(0x01,TCCR0); /* Divisor: 1/1 clock */

   ind=inp(PINB);  /*initialize quad inputs to avoid error signal on startup*/

   qinpx=(ind&0x03)<<2;
   ind>>=2;

   qinpy=(ind&0x03)<<2;
   ind>>=2;

   qinpz=(ind&0x03)<<2;


   acntx=0; acnty=0; acntz=0;
   zerox[0]=0;
   zeroy[0]=0;

   merrorx=0;
   merrory=0;

   sei(); /* enable interrupt */

   init_leds();

   while (1) {
   check_keyb();
   write_leds(); }
}