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CommandStation-EX/DCCTimerAVR.cpp

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/*
* © 2021 Mike S
* © 2021-2023 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 <avr/wdt.h>
#include "DCCTimer.h"
#include "DIAG.h"
#ifdef DEBUG_ADC
#include "TrackManager.h"
#endif
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
#define TIMER2_A_PIN 10
#define TIMER2_B_PIN 9
#else
#define TIMER1_A_PIN 9
#define TIMER1_B_PIN 10
#endif
void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
interruptHandler=callback;
noInterrupts();
TCCR1A = 0;
ICR1 = CLOCK_CYCLES;
TCNT1 = 0;
TCCR1B = _BV(WGM13) | _BV(CS10); // Mode 8, clock select 1
TIMSK1 = _BV(TOIE1); // Enable Software interrupt
interrupts();
}
void DCCTimer::startRailcomTimer(byte brakePin) {
/* The Railcom timer is started in such a way that it
- First triggers 28uS after the last TIMER1 tick.
This provides an accurate offset (in High Accuracy mode)
for the start of the Railcom cutout.
- Sets the Railcom pin high at first tick,
because its been setup with 100% PWM duty cycle.
- Cycles at 436uS so the second tick is the
correct distance from the cutout.
- Waveform code is responsible for altering the PWM
duty cycle to 0% any time between the first and last tick.
(there will be 7 DCC timer1 ticks in which to do this.)
*/
(void) brakePin; // Ignored... works on pin 9 only
const int cutoutDuration = 430; // Desired interval in microseconds
// Set up Timer2 for CTC mode (Clear Timer on Compare Match)
TCCR2A = 0; // Clear Timer2 control register A
TCCR2B = 0; // Clear Timer2 control register B
TCNT2 = 0; // Initialize Timer2 counter value to 0
// Configure Phase and Frequency Correct PWM mode
TCCR2A = (1 << COM2B1); // enable pwm on pin 9
TCCR2A |= (1 << WGM20);
// Set Timer 2 prescaler to 32
TCCR2B = (1 << CS21) | (1 << CS20); // 32 prescaler
// Set the compare match value for desired interval
OCR2A = (F_CPU / 1000000) * cutoutDuration / 64 - 1;
// Calculate the compare match value for desired duty cycle
OCR2B = OCR2A+1; // set duty cycle to 100%= OCR2A)
// Enable Timer2 output on pin 9 (OC2B)
DDRB |= (1 << DDB1);
// TODO Fudge TCNT2 to sync with last tcnt1 tick + 28uS
// Previous TIMER1 Tick was at rising end-of-packet bit
// Cutout starts half way through first preamble
// that is 2.5 * 58uS later.
// TCNT1 ticks 8 times / microsecond
// auto microsendsToFirstRailcomTick=(58+58+29)-(TCNT1/8);
// set the railcom timer counter allowing for phase-correct
// CHris's NOTE:
// I dont kniow quite how this calculation works out but
// it does seems to get a good answer.
TCNT2=193 + (ICR1 - TCNT1)/8;
}
void DCCTimer::ackRailcomTimer() {
OCR2B= 0x00; // brake pin pwm duty cycle 0 at next tick
}
// 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::clearPWM() {
TCCR1A= 0;
}
void DCCTimer::getSimulatedMacAddress(byte mac[6]) {
for (byte i=0; i<6; i++) {
// take the fist 3 and last 3 of the serial.
// the first 5 of 8 are at 0x0E to 0x013
// the last 3 of 8 are at 0x15 to 0x017
mac[i]=boot_signature_byte_get(0x0E + i + (i>2? 4 : 0));
}
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;
}
void DCCTimer::reset() {
// 250ms chosen to circumwent bootloader bug which
// hangs at too short timepout (like 15ms)
wdt_enable( WDTO_250MS); // set Arduino watchdog timer for 250ms
delay(500); // wait for it to happen
}
void DCCTimer::DCCEXanalogWriteFrequency(uint8_t pin, uint32_t f) {
DCCTimer::DCCEXanalogWriteFrequencyInternal(pin, f);
}
void DCCTimer::DCCEXanalogWriteFrequencyInternal(uint8_t pin, uint32_t fbits) {
#if defined(ARDUINO_AVR_UNO)
// Not worth doin something here as:
// If we are on pin 9 or 10 we are on Timer1 and we can not touch Timer1 as that is our DCC source.
// If we are on pin 5 or 6 we are on Timer 0 ad we can not touch Timer0 as that is millis() etc.
// We are most likely not on pin 3 or 11 as no known motor shield has that as brake.
#endif
#if defined(ARDUINO_AVR_MEGA) || defined(ARDUINO_AVR_MEGA2560)
// Speed mapping is done like this:
// No functions buttons: 000 0 -> low 131Hz
// Only F29 pressed 001 1 -> mid 490Hz
// F30 with or w/o F29 01x 2-3 -> high 3400Hz
// F31 with or w/o F29/30 1xx 4-7 -> supersonic 62500Hz
uint8_t abits;
uint8_t bbits;
if (pin == 9 || pin == 10) { // timer 2 is different
if (fbits >= 4)
abits = B00000011;
else
abits = B00000001;
if (fbits >= 4)
bbits = B0001;
else if (fbits >= 2)
bbits = B0010;
else if (fbits == 1)
bbits = B0100;
else // fbits == 0
bbits = B0110;
TCCR2A = (TCCR2A & B11111100) | abits; // set WGM0 and WGM1
TCCR2B = (TCCR2B & B11110000) | bbits; // set WGM2 and 3 bits of prescaler
DIAG(F("Timer 2 A=%x B=%x"), TCCR2A, TCCR2B);
} else { // not timer 9 or 10
abits = B01;
if (fbits >= 4)
bbits = B1001;
else if (fbits >= 2)
bbits = B0010;
else if (fbits == 1)
bbits = B0011;
else
bbits = B0100;
switch (pin) {
// case 9 and 10 taken care of above by if()
case 6:
case 7:
case 8:
// Timer4
TCCR4A = (TCCR4A & B11111100) | abits; // set WGM0 and WGM1
TCCR4B = (TCCR4B & B11100000) | bbits; // set WGM2 and WGM3 and divisor
//DIAG(F("Timer 4 A=%x B=%x"), TCCR4A, TCCR4B);
break;
case 46:
case 45:
case 44:
// Timer5
TCCR5A = (TCCR5A & B11111100) | abits; // set WGM0 and WGM1
TCCR5B = (TCCR5B & B11100000) | bbits; // set WGM2 and WGM3 and divisor
//DIAG(F("Timer 5 A=%x B=%x"), TCCR5A, TCCR5B);
break;
default:
break;
}
}
#endif
}
#if defined(ARDUINO_AVR_MEGA) || defined(ARDUINO_AVR_MEGA2560)
#define NUM_ADC_INPUTS 16
#else
#define NUM_ADC_INPUTS 8
#endif
uint16_t ADCee::usedpins = 0;
uint8_t ADCee::highestPin = 0;
int * ADCee::analogvals = NULL;
static bool ADCusesHighPort = false;
/*
* Register a new pin to be scanned
* Returns current reading of pin and
* stores that as well
*/
int ADCee::init(uint8_t pin) {
uint8_t id = pin - A0;
if (id >= NUM_ADC_INPUTS)
return -1023;
if (id > 7)
ADCusesHighPort = true;
pinMode(pin, INPUT);
int value = analogRead(pin);
if (analogvals == NULL)
analogvals = (int *)calloc(NUM_ADC_INPUTS, sizeof(int));
analogvals[id] = value;
usedpins |= (1<<id);
if (id > highestPin) highestPin = id;
return value;
}
int16_t ADCee::ADCmax() {
return 1023;
}
/*
* Read function ADCee::read(pin) to get value instead of analogRead(pin)
*/
int ADCee::read(uint8_t pin, bool fromISR) {
uint8_t id = pin - A0;
if ((usedpins & (1<<id) ) == 0)
return -1023;
// we do not need to check (analogvals == NULL)
// because usedpins would still be 0 in that case
if (!fromISR) noInterrupts();
int a = analogvals[id];
if (!fromISR) interrupts();
return a;
}
/*
* Scan function that is called from interrupt
*/
#pragma GCC push_options
#pragma GCC optimize ("-O3")
void ADCee::scan() {
static byte id = 0; // id and mask are the same thing but it is faster to
static uint16_t mask = 1; // increment and shift instead to calculate mask from id
static bool waiting = false;
if (waiting) {
// look if we have a result
byte low, high;
if (bit_is_set(ADCSRA, ADSC))
return; // no result, continue to wait
// found value
low = ADCL; //must read low before high
high = ADCH;
bitSet(ADCSRA, ADIF);
analogvals[id] = (high << 8) | low;
// advance at least one track
#ifdef DEBUG_ADC
if (id == 1) TrackManager::track[1]->setBrake(0);
#endif
waiting = false;
id++;
mask = mask << 1;
if (id > highestPin) {
id = 0;
mask = 1;
}
}
if (!waiting) {
if (usedpins == 0) // otherwise we would loop forever
return;
// look for a valid track to sample or until we are around
while (true) {
if (mask & usedpins) {
// start new ADC aquire on id
#if defined(ADCSRB) && defined(MUX5)
if (ADCusesHighPort) { // if we ever have started to use high pins)
if (id > 7) // if we use a high ADC pin
bitSet(ADCSRB, MUX5); // set MUX5 bit
else
bitClear(ADCSRB, MUX5);
}
#endif
ADMUX=(1<<REFS0)|(id & 0x07); //select AVCC as reference and set MUX
bitSet(ADCSRA,ADSC); // start conversion
#ifdef DEBUG_ADC
if (id == 1) TrackManager::track[1]->setBrake(1);
#endif
waiting = true;
return;
}
id++;
mask = mask << 1;
if (id > highestPin) {
id = 0;
mask = 1;
}
}
}
}
#pragma GCC pop_options
void ADCee::begin() {
noInterrupts();
// ADCSRA = (ADCSRA & 0b11111000) | 0b00000100; // speed up analogRead sample time
// Set up ADC for free running mode
ADMUX=(1<<REFS0); //select AVCC as reference. We set MUX later
ADCSRA = (1<<ADEN)|(1 << ADPS2); // ADPS2 means divisor 32 and 16Mhz/32=500kHz.
//bitSet(ADCSRA, ADSC); //do not start the ADC yet. Done when we have set the MUX
interrupts();
}
#endif
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