TID.c

/*

 *  TID.c

 *  fuelmeter

 *

 *  Created by Alexander Peters on 25.12.07.

 *  Copyright 2007 __MyCompanyName__. All rights reserved.

 *

 */

#include <TID.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include <util/delay.h>

#include <string.h>

#define _PORT    PORTD

#define _DDR    DDRD

#define _PIN    PIND

#define _SCL_out  0

#define _SCL_in    1

#define _MRQ_out  2

#define _MRQ_in    3

#define  _SDA_out  4

#define _SDA_in    5

#define _AA      6

#define _address  0x4A

#define _step 128

char string[9] = "TEST    ";

volatile char symbol[2], buffer[10];

volatile uint8_t state, mark, bitToSend, ByteToSend, cyclesRem;

void MRQ_high(void){

  _PORT &= ~(1<<_MRQ_out);

}

void MRQ_low(void){

  _PORT |= (1<<_MRQ_out);

}

void SCL_high(void){

  _PORT &= ~(1<<_SCL_out);

}

void SCL_low(void){

  _PORT |= (1<<_SCL_out);

}

void SDA_high(void){

  _PORT &= ~(1<<_SDA_out);

}

void SDA_low(void){

  _PORT |= (1<<_SDA_out);

}

uint8_t get_MRQ(void){

  return (_PIN & (1<< _MRQ_in));

}

uint8_t get_SCL(void){

  return (_PIN & (1<< _SCL_in));

}

uint8_t get_SDA(void){

  return (_PIN & (1<< _SDA_in));

}

void init_DDR(void){

  _DDR = (0<< _MRQ_in | 1<< _MRQ_out | 0<< _SCL_in | 1<< _SCL_out | 0<< _SDA_in |1<< _SDA_out | 1<<_AA);

}

void init_timer(void){

  TCCR2 = (0<<FOC2 | 0<<WGM20 | 0<<COM21 | 0<<COM20 | 0<<WGM21 | 1<<CS22 | 1<<CS21 | 1<<CS20);    //normal operation, prescaler 1024

  TIMSK &= ~(1<<TOIE2 | 1<<OCIE2);      //timer2 overflow/output compare interrupt disabled

}

void enable_timer_int(void){

  TIMSK |= (1<<TOIE2);            //timer2 overflow interrupt enabled

}

void disable_timer_int(void){

  TIMSK &= ~(1<<TOIE2);            //timer2 overflow interrupt disabled

}

void start_timer_ns(uint16_t ns){

  uint16_t steps = (ns/_step);

  cyclesRem=steps/256;

  TCNT2=(steps-(cyclesRem*256));

  enable_timer_int();

}

void start_timer_us(uint16_t us){

  uint16_t steps = (1000*(us/_step));

  cyclesRem=steps/256;

  TCNT2=(steps-(cyclesRem*256));

  enable_timer_int();

}

void delay_50us(uint8_t i){

  for(;i>0;i--){

    _delay_us(50);

  }

}

void TID_on(void){  

  _PORT  |=  (1 << _AA);            //set bit

  for(uint8_t i=0; i<100;i++){        //warte 1sec

    _delay_ms(10);

  }

  state=1;

}

void TID_off(void){

  _PORT  &=  ~(1<< _AA);            //clear bit

  state=0;

}

void TID_init(void){

  init_DDR();

  init_timer();

  SDA_high();

  SCL_high();

  MRQ_high();

  sei();

}

void send_start(void){

  PORTC=1;

  MRQ_low();

  while(get_SDA());        //warte bis SDA low

  delay_50us(2);

  MRQ_high();

  PORTC=2;

  while(!get_SDA());        //warte bis SDA high

  delay_50us(2);

  SDA_low();

  delay_50us(3);

  SCL_low();

  delay_50us(3);

  PORTC=3;

}

void send_stop(void){

  SDA_low();

  delay_50us(2);

  MRQ_high();

  delay_50us(2);

  SCL_high();

  delay_50us(2);

  SDA_high();

  delay_50us(2);

}

void send_bit(uint8_t bit){

  if(bit){            //put bit on bus

    SDA_high();

  }else{

    SDA_low();

  }

  _delay_us(5);

  SCL_high();            //set bit valid

  while(!get_SCL());        //wait for slave    

  delay_50us(1);          //wait

  SCL_low();

  _delay_us(50);

}

uint8_t end_Byte(void){

  uint8_t ack;

  SDA_high();

  delay_50us(1);

  SCL_high();

  while(!get_SCL());

  ack=get_SDA();

  delay_50us(1);

  SDA_low();

  while(!get_SDA());

  delay_50us(2);

  return ack;

}

void send_Byte(char Byte){

  uint8_t parity=1;

  for(uint8_t i=6; i>0; i--){

    if((Byte & ~(1<<i))){

      parity = !parity;

    }

    send_bit((Byte & ~(1<<i)));

  }

  send_bit(parity);

  PORTC=end_Byte();  

}

void TID_update(void){

  TID_init();

  TID_on();

  symbol[0]=0x10;

  symbol[1]=0x01;

  send_start();

  send_Byte(_address);

  delay_50us(2);

  MRQ_low();

  delay_50us(2);

  for(uint8_t i=0; i<2;i++){

    send_Byte(symbol[i]);

  }

  for(uint8_t i=0; i<8;i++){

    send_Byte(string[i]);

  }

  send_stop();

}