/*
* © 2021, Chris Harlow & 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.
*
*/
#include "DCCTimer.h"
const int DCC_SIGNAL_TIME=58; // this is the 58uS DCC 1-bit waveform half-cycle
const long CLOCK_CYCLES=(F_CPU / 1000000 * DCC_SIGNAL_TIME) >>1;
INTERRUPT_CALLBACK interruptHandler=0;
#ifdef ARDUINO_ARCH_MEGAAVR
// Arduino unoWifi Rev2 and nanoEvery architectire
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;
interruptHandler();
}
bool DCCTimer::isPWMPin(byte pin) {
return false; // TODO what are the relevant pins?
}
void DCCTimer::setPWM(byte pin, bool high) {
// TODO what are the relevant pins?
}
void DCCTimer::getSimulatedMacAddress(byte mac[6]) {
memcpy(mac,(void *) &SIGROW.SERNUM0,6); // serial number
}
#elif defined(TEENSYDUINO)
IntervalTimer myDCCTimer;
void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
interruptHandler=callback;
myDCCTimer.begin(interruptHandler, DCC_SIGNAL_TIME);
}
bool DCCTimer::isPWMPin(byte pin) {
//Teensy: digitalPinHasPWM, todo
return false; // TODO what are the relevant pins?
}
void DCCTimer::setPWM(byte pin, bool high) {
// TODO what are the relevant pins?
}
void DCCTimer::getSimulatedMacAddress(byte mac[6]) {
#if defined(__IMXRT1062__) //Teensy 4.0 and Teensy 4.1
uint32_t m1 = HW_OCOTP_MAC1;
uint32_t m2 = HW_OCOTP_MAC0;
mac[0] = m1 >> 8;
mac[1] = m1 >> 0;
mac[2] = m2 >> 24;
mac[3] = m2 >> 16;
mac[4] = m2 >> 8;
mac[5] = m2 >> 0;
#else
read_mac(mac);
#endif
}
#if !defined(__IMXRT1062__)
void DCCTimer::read_mac(byte mac[6]) {
read(0xe,mac,0);
read(0xf,mac,3);
}
// http://forum.pjrc.com/threads/91-teensy-3-MAC-address
void DCCTimer::read(uint8_t word, uint8_t *mac, uint8_t offset) {
FTFL_FCCOB0 = 0x41; // Selects the READONCE command
FTFL_FCCOB1 = word; // read the given word of read once area
// launch command and wait until complete
FTFL_FSTAT = FTFL_FSTAT_CCIF;
while(!(FTFL_FSTAT & FTFL_FSTAT_CCIF));
*(mac+offset) = FTFL_FCCOB5; // collect only the top three bytes,
*(mac+offset+1) = FTFL_FCCOB6; // in the right orientation (big endian).
*(mac+offset+2) = FTFL_FCCOB7; // Skip FTFL_FCCOB4 as it's always 0.
}
#endif
#else
// 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
}
#include
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;
}
#endif