/* * © 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 . */ /* This timer class is used to manage the single timer required to handle the DCC waveform. * All timer access comes through this class so that it can be compiled for * various hardware CPU types. * * DCCEX works on a single timer interrupt at a regular 58uS interval. * The DCCWaveform class generates the signals to the motor shield * based on this timer. * * If the motor drivers are BOTH configured to use the correct 2 pins for the architecture, * (see isPWMPin() function. ) * then this allows us to use a hardware driven pin switching arrangement which is * achieved by setting the duty cycle of the NEXT clock interrupt to 0% or 100% depending on * the required pin state. (see setPWM()) * This is more accurate than the software interrupt but at the expense of * limiting the choice of available pins. * Fortunately, a standard motor shield on a Mega uses pins that qualify for PWM... * Other shields may be jumpered to PWM pins or run directly using the software interrupt. * * Because the PWM-based waveform is effectively set half a cycle after the software version, * it is not acceptable to drive the two tracks on different methiods or it would cause * problems for <1 JOIN> etc. * */ // ATTENTION: this file only compiles on a UnoWifiRev3 or NanoEvery // Please refer to DCCTimer.h for general comments about how this class works // This is to avoid repetition and duplication. #ifdef ARDUINO_ARCH_MEGAAVR #include "DCCTimer.h" INTERRUPT_CALLBACK interruptHandler=0; extern char *__brkval; extern char *__malloc_heap_start; void DCCTimer::begin(INTERRUPT_CALLBACK callback) { interruptHandler=callback; noInterrupts(); ADC0.CTRLC = (ADC0.CTRLC & 0b00110000) | 0b01000011; // speed up analogRead sample time TCB0.CTRLB = TCB_CNTMODE_INT_gc & ~TCB_CCMPEN_bm; // timer compare mode with output disabled TCB0.CTRLA = TCB_CLKSEL_CLKDIV2_gc; // 8 MHz ~ 0.125 us TCB0.CCMP = CLOCK_CYCLES -1; // 1 tick less for timer reset TCB0.INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag TCB0.INTCTRL = TCB_CAPT_bm; // Enable the interrupt TCB0.CNT = 0; TCB0.CTRLA |= TCB_ENABLE_bm; // start interrupts(); } // ISR called by timer interrupt every 58uS ISR(TCB0_INT_vect){ TCB0.INTFLAGS = TCB_CAPT_bm; // Clear interrupt request flag interruptHandler(); } bool DCCTimer::isPWMPin(byte pin) { (void) pin; return false; // TODO what are the relevant pins? } void DCCTimer::setPWM(byte pin, bool high) { (void) pin; (void) high; // TODO what are the relevant pins? } void DCCTimer::getSimulatedMacAddress(byte mac[6]) { memcpy(mac,(void *) &SIGROW.SERNUM0,6); // serial number 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