CommandStation-EX/DCCTimerAVR.cpp

/*
 *  © 2021 Mike S
 *  © 2021 Harald Barth
 *  © 2021 Fred Decker
 *  © 2021 Chris Harlow
 *  © 2021 David Cutting
 *  All rights reserved.
 *  
 *  This file is part of Asbelos DCC API
 *
 *  This 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  It 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 CommandStation.  If not, see <https://www.gnu.org/licenses/>.
 */

// ATTENTION: this file only compiles on a UNO or MEGA
// Please refer to DCCTimer.h for general comments about how this class works
// This is to avoid repetition and duplication.
#ifdef ARDUINO_ARCH_AVR

#include <avr/boot.h> 
#include "DCCTimer.h"
INTERRUPT_CALLBACK interruptHandler=0;

  // Arduino nano, uno, mega etc
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
    #define TIMER1_A_PIN   11
    #define TIMER1_B_PIN   12
    #define TIMER1_C_PIN   13
#else
   #define TIMER1_A_PIN   9
   #define TIMER1_B_PIN   10
#endif

void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
    interruptHandler=callback;
    noInterrupts();          
    ADCSRA = (ADCSRA & 0b11111000) | 0b00000100;   // speed up analogRead sample time 
    TCCR1A = 0;
    ICR1 = CLOCK_CYCLES;
    TCNT1 = 0;   
    TCCR1B = _BV(WGM13) | _BV(CS10);     // Mode 8, clock select 1
    TIMSK1 = _BV(TOIE1); // Enable Software interrupt
    interrupts();
  }

// ISR called by timer interrupt every 58uS
  ISR(TIMER1_OVF_vect){ interruptHandler(); }

// Alternative pin manipulation via PWM control.
  bool DCCTimer::isPWMPin(byte pin) {
       return pin==TIMER1_A_PIN 
           || pin==TIMER1_B_PIN
       #ifdef TIMER1_C_PIN 
           || pin==TIMER1_C_PIN
       #endif       
       ;
  }

 void DCCTimer::setPWM(byte pin, bool high) {
    if (pin==TIMER1_A_PIN) {
      TCCR1A |= _BV(COM1A1);
      OCR1A= high?1024:0;
    }
    else if (pin==TIMER1_B_PIN) { 
      TCCR1A |= _BV(COM1B1);
      OCR1B= high?1024:0;
    }
 #ifdef TIMER1_C_PIN 
    else if (pin==TIMER1_C_PIN) { 
      TCCR1A |= _BV(COM1C1);
      OCR1C= high?1024:0;
    }
 #endif       
 }

  void DCCTimer::getSimulatedMacAddress(byte mac[6]) {
    for (byte i=0; i<6; i++) {
      mac[i]=boot_signature_byte_get(0x0E + i);
    }
    mac[0] &= 0xFE;
    mac[0] |= 0x02;
  }


volatile int DCCTimer::minimum_free_memory=__INT_MAX__;

// Return low memory value... 
int DCCTimer::getMinimumFreeMemory() {
  noInterrupts(); // Disable interrupts to get volatile value 
  int retval = minimum_free_memory;
  interrupts();
  return retval;
}

extern char *__brkval;
extern char *__malloc_heap_start;

int DCCTimer::freeMemory() {
  char top;
  return __brkval ? &top - __brkval : &top - __malloc_heap_start;
}

#endif