mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-11-24 00:26:13 +01:00
73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
/*
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* © 2021, Chris Harlow & David Cutting. All rights reserved.
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*
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* This file is part of Asbelos DCC API
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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/* This timer class is used to manage the single timer required to handle the DCC waveform.
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* All timer access comes through this class so that it can be compiled for
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* various hardware CPU types.
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*
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* DCCEX works on a single timer interrupt at a regular 58uS interval.
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* The DCCWaveform class generates the signals to the motor shield
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* based on this timer.
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*/
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#include "DCCTimer.h"
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const int DCC_SIGNAL_TIME=58; // this is the 58uS DCC 1-bit waveform half-cycle
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const long CLOCK_CYCLES=(F_CPU / 1000000 * DCC_SIGNAL_TIME) >>1;
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INTERRUPT_CALLBACK interruptHandler=0;
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#ifdef ARDUINO_ARCH_MEGAAVR
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// Arduino unoWifi Rev2 and nanoEvery architectire
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void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
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interruptHandler=callback;
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noInterrupts();
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TCB0.CTRLB = TCB_CNTMODE_INT_gc & ~TCB_CCMPEN_bm; // timer compare mode with output disabled
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TCB0.CTRLA = TCB_CLKSEL_CLKDIV2_gc; // 8 MHz ~ 0.125 us
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TCB0.CCMP = CLOCK_CYCLES -1; // 1 tick less for timer reset
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TCB0.INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
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TCB0.INTCTRL = TCB_CAPT_bm; // Enable the interrupt
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TCB0.CNT = 0;
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TCB0.CTRLA |= TCB_ENABLE_bm; // start
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interrupts();
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}
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// ISR called by timer interrupt every 58uS
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ISR(TCB0_INT_vect){
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TCB0.INTFLAGS = TCB_CAPT_bm;
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interruptHandler();
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}
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#else
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// Arduino nano, uno, mega etc
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void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
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interruptHandler=callback;
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noInterrupts();
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TCCR1A = 0;
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ICR1 = CLOCK_CYCLES;
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TCNT1 = 0;
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TCCR1B = _BV(WGM13) | _BV(CS10); // Mode 8, clock select 1
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TIMSK1 = _BV(TOIE1); // Enable Software interrupt
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interrupts();
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}
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// ISR called by timer interrupt every 58uS
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ISR(TIMER1_OVF_vect){ interruptHandler(); }
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#endif
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