comm.c

Go to the documentation of this file.

/*
 * comm.c
 *
 *  Created on: Jan 2, 2014
 *      Author: woodz
 */
#include "comm.h"
#include "timer.h"
#include <util/crc16.h>

//UCHAR volatile g_comDataReady = FALSE;
UCHAR g_seq[SEQ_BUF_SIZE];
UCHAR volatile g_seqReady = FALSE;

void CommInit(void) {
  //disable USI module to avoid overriding of the PCINT8 functionality
  DisableUsi();
  //PCINT8 is used to receive serial bits, the DI line of the USI module
  //set PCINT8 the DI pin as input, the DO pin is not changed, since we just receive and on DO there is a button connected
  DDRB &= ~(1<<PCINT8);
  //enabling pullup on DO is omitted, since we do not transmit anything
  //enable pin change interrupts for group PCINT11..8
  GIMSK = (0<<INT1) | (0<<INT0) | (0<<PCIE1) | (1<<PCIE0);
  GIFR = (0<<INT1) | (0<<INTF0) | (1<<PCIF);
  //enable specific pin change PCINT8, disable all others
  PCMSK0 = (0<<PCINT7) | (0<<PCINT6) | (0<<PCINT5) | (0<<PCINT4) | (0<<PCINT3) | (0<<PCINT2) | (0<<PCINT1) | (0<<PCINT0);
  EnablePcint8();
}

ISR(PCINT_vect) {
  //start bit detection:
  //DATABIT = 0 -> start bit has begun
  //DATABIT = 1 -> start bit has finished
  //start bit is over?
  if(DATABIT == TRUE) {
    DisablePcint8();
    EnableUsi();
  }
}

void EnablePcint8(void) {
  //clear PCINT interrupt flag to avoid likely queued requests to execute immediately
  GIFR |= (1<<PCIF);
  PCMSK1 = (0<<PCINT15) | (0<<PCINT14) | (0<<PCINT13) | (0<<PCINT12) | (0<<PCINT11) | (0<<PCINT10) | (0<<PCINT9) | (1<<PCINT8);
}

void DisablePcint8(void) {
  PCMSK1 = (0<<PCINT15) | (0<<PCINT14) | (0<<PCINT13) | (0<<PCINT12) | (0<<PCINT11) | (0<<PCINT10) | (0<<PCINT9) | (0<<PCINT8);
}

void DisableUsi(void) {
  USISR = (0<<USISIF) | (0<<USIOIF) | (0<<USIPF) | (0<<USICNT3) | (0<<USICNT2) | (0<<USICNT1) | (0<<USICNT0);
  USICR = (0<<USISIE) | (0<<USIOIE) | (0<<USIWM1) | (0<<USIWM0) | (0<<USICS1) | (0<<USICS0) | (0<<USICLK) | (0<<USITC);
}

void EnableUsi(void) {
  //plant initial Timer0 seed (and compare match value)
  TCN_T0 = 0;
  OCR0A = T0_INC20 + (T0_INC20 / 2);
  //plant USI counter seed
  USISR &= (0xf0 + (USI_CNTRNG - NUM_DB));
  USISR |= USI_CNTRNG - NUM_DB;
//  USISR &= ~(USI_CNTRNG - NUM_DB);
  //set three-wire-mode, clock source to timer0 compare match and enable USI counter overflow interrupt
  USICR &= ~0x0A;
  USICR |= (1<<USIOIE) | (1<<USIWM0) | (0<<USICS1) | (1<<USICS0) | (0<<USICLK);
}

ISR(USI_OVF_vect) {
  static UCHAR sCnt=0;
  UCHAR curByte = 0;

  DisableUsi();
  EnablePcint8();

  //do no sequencing as long as the previous seq has not been processed
  if(g_seqReady) { return; }
  curByte = ~FlipByte(USIBR);
  if((curByte == SEQ_STA) && (sCnt == 0)) {
    ++sCnt;
    return;
  }
  //store received byte in sequence buffer
  if(sCnt >= 1) {
    g_seq[sCnt] = curByte;
    if(++sCnt >= SEQ_BUF_SIZE) {
      sCnt = 0;
      if(curByte == SEQ_END) {
        g_seqReady = TRUE;
      }
    }
  }
}

UCHAR GetSenderValues(UINT* innerTemp, UINT* outerTemp/*, UINT* supVolt*/) {
  UCHAR ret = FALSE;

  if(g_seqReady && (CalcCrc() == 0)) {
    *innerTemp = g_seq[TEMP_CH1_VAL_H_ID] << 8;
    *innerTemp |= g_seq[TEMP_CH1_VAL_L_ID];
    *outerTemp = g_seq[TEMP_CH2_VAL_H_ID] << 8;
    *outerTemp |= g_seq[TEMP_CH2_VAL_L_ID];
//    *supVolt = g_seq[SUP_VOLT_VAL_H_ID] << 8;
//    *supVolt |= g_seq[SUP_VOLT_VAL_L_ID];
//    if(PlausibilityCheck(*innerTemp, *outerTemp))
    ret = TRUE;
  }
  else {
    *innerTemp = INVALID_VAL_U16;
    *outerTemp = INVALID_VAL_U16;
//  *supVolt   = INVALID_VAL_U16;
    ret =  FALSE;
  }
  g_seqReady = FALSE;
  return ret;
}

UCHAR PlausibilityCheck(UINT innerTemp, UINT outerTemp) {
  static UINT oldInnerTemp = INVALID_VAL_U16;
  static UINT oldOuterTemp = INVALID_VAL_U16;
  UCHAR ret=FALSE;
  UINT dIn = innerTemp - oldInnerTemp, dOut = outerTemp - oldOuterTemp;

  if(innerTemp != INVALID_VAL_U16 && outerTemp != INVALID_VAL_U16) {
    if(innerTemp <= MAX_ABS_INNER_TEMP && innerTemp >= MIN_ABS_INNER_TEMP
    && outerTemp <= MAX_ABS_OUTER_TEMP && outerTemp >= MIN_ABS_OUTER_TEMP
    && (dIn <= MAX_DEL_INNER_TEMP || (INVALID_VAL_U16 - dIn) <= MAX_DEL_INNER_TEMP)
    && (dOut <= MAX_DEL_OUTER_TEMP || (INVALID_VAL_U16 - dOut) <= MAX_DEL_OUTER_TEMP))
      ret=TRUE;
  }
  oldInnerTemp = innerTemp;
  oldOuterTemp = outerTemp;
  return ret;
}

UCHAR CalcCrc(void) {
  UCHAR crc = 0;

  crc = _crc_ibutton_update(crc, g_seq[TEMP_CH1_VAL_H_ID]);
  crc = _crc_ibutton_update(crc, g_seq[TEMP_CH1_VAL_L_ID]);
  crc = _crc_ibutton_update(crc, g_seq[TEMP_CH2_VAL_H_ID]);
  crc = _crc_ibutton_update(crc, g_seq[TEMP_CH2_VAL_L_ID]);
  crc = _crc_ibutton_update(crc, g_seq[SUP_VOLT_VAL_H_ID]);
  crc = _crc_ibutton_update(crc, g_seq[SUP_VOLT_VAL_L_ID]);
  crc = _crc_ibutton_update(crc, g_seq[CRC_OVER_ALL]);
  return crc;
}

//UCHAR StartBitElapsed(UCHAR started) {
//  static UCHAR nextCnt = 0xFF;
//
//  if(started) {
//    if(TCN_T0 > MAX_STB_CNT)
//      nextCnt = TCN_T0 - (MAX_STB_CNT + 1);
//    else
//      nextCnt = TCN_T0 + OAHBT;
//  }
//  else if(TCN_T0 == nextCnt)
//    return TRUE;
//  return FALSE;
//}