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278 lines
7.8 KiB
278 lines
7.8 KiB
/*
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|| @author Brett Hagman <bhagman@wiring.org.co>
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|| @contribution Paul Stoffregen (paul at pjrc dot com)
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|| @url http://wiring.org.co/
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|| @url http://roguerobotics.com/
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||
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|| @description
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|| | A Software PWM Library
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|| |
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|| | Written by Brett Hagman
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|| | http://www.roguerobotics.com/
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|| | bhagman@roguerobotics.com, bhagman@wiring.org.co
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|| |
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|| | A Wiring (and Arduino) Library, for Atmel AVR8 bit series microcontrollers,
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|| | to produce PWM signals on any arbitrary pin.
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|| |
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|| | It was originally designed for controlling the brightness of LEDs, but
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|| | could be adapted to control servos and other low frequency PWM controlled
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|| | devices as well.
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|| |
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|| | It uses a single hardware timer (Timer 2) on the Atmel microcontroller to
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|| | generate up to 20 PWM channels (your mileage may vary).
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|| |
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|| #
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||
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|| @license Please see the accompanying LICENSE.txt file for this project.
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||
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|| @notes
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|| | Minor modification by Paul Stoffregen to support different timers.
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|| |
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|| #
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||
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|| @name Software PWM Library
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|| @type Library
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|| @target Atmel AVR 8 Bit
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||
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|| @version 1.0.1
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||
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*/
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "SoftPWM.h"
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#include "SoftPWM_timer.h"
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#if defined(WIRING)
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#include <wiring_private.h>
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#elif ARDUINO >= 100
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#include <Arduino.h>
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#else
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#include <Arduino.h>
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#endif
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#if F_CPU
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#define SOFTPWM_FREQ 60UL
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#define SOFTPWM_OCR (F_CPU/(8UL*256UL*SOFTPWM_FREQ))
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#else
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// 130 == 60 Hz (on 16 MHz part)
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#define SOFTPWM_OCR 130
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#endif
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volatile uint8_t _isr_softcount = 0xff;
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uint8_t _softpwm_defaultPolarity = SOFTPWM_NORMAL;
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typedef struct {
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// hardware I/O port and pin for this channel
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int8_t pin;
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uint8_t polarity;
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volatile uint8_t *outport;
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uint8_t pinmask;
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uint8_t pwmvalue;
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uint8_t checkval;
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uint8_t fadeuprate;
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uint8_t fadedownrate;
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} softPWMChannel;
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softPWMChannel _softpwm_channels[SOFTPWM_MAXCHANNELS];
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// Here is the meat and gravy
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#ifdef WIRING
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void SoftPWM_Timer_Interrupt(void)
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#else
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ISR(TIMER1_COMPA_vect)
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#endif
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{
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uint8_t i;
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int16_t newvalue;
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int16_t direction;
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if (++_isr_softcount == 0)
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{
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// set all channels high - let's start again
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// and accept new checkvals
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for (i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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// check on pwm, 0-255
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_softpwm_channels[i].checkval = _softpwm_channels[i].pwmvalue;
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// now set the pin high (if not 0)
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if (_softpwm_channels[i].checkval > 0)
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{
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if (_softpwm_channels[i].polarity == SOFTPWM_NORMAL)
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*_softpwm_channels[i].outport |= _softpwm_channels[i].pinmask;
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else
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*_softpwm_channels[i].outport &= ~(_softpwm_channels[i].pinmask);
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}
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}
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}
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for (i = 0; i < SOFTPWM_MAXCHANNELS; i++)
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{
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if (_softpwm_channels[i].pin >= 0) // Only set un-flagged pins
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{
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if (_softpwm_channels[i].checkval == _isr_softcount) // if we have hit the width
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{
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// turn off the channel
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if (_softpwm_channels[i].polarity == SOFTPWM_NORMAL)
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*_softpwm_channels[i].outport &= ~(_softpwm_channels[i].pinmask);
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else
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*_softpwm_channels[i].outport |= _softpwm_channels[i].pinmask;
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}
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}
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}
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}
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void SoftPWMBegin(uint8_t defaultPolarity) {
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// We can tweak the number of PWM period by changing the prescalar
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// and the OCR - we'll default to ck/8 (CS21 set) and OCR=128.
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// This gives 1024 cycles between interrupts. And the ISR consumes ~200 cycles, so
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// we are looking at about 20 - 30% of CPU time spent in the ISR.
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// At these settings on a 16 MHz part, we will get a PWM period of
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// approximately 60Hz (~16ms).
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// Hand init
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cli(); // Disable interrupts while setting registers
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TCCR1A = 0; // Reset the timer
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TCCR1B = 0; // Reset the timer
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TIMSK1 = (1 << OCIE1A); // Enable interrupt
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TCCR1B = (1 << CS21); /* start timer (ck/8 prescalar) */ \
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TCCR1A = (1 << WGM21); /* CTC mode */ \
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OCR1A = SOFTPWM_OCR; // compare value
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sei();
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for (uint8_t i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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_softpwm_channels[i].pin = -1;
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_softpwm_channels[i].polarity = SOFTPWM_NORMAL;
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_softpwm_channels[i].outport = 0;
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_softpwm_channels[i].fadeuprate = 0;
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_softpwm_channels[i].fadedownrate = 0;
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}
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_softpwm_defaultPolarity = defaultPolarity;
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}
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void SoftPWMSetPolarity(int8_t pin, uint8_t polarity) {
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uint8_t i;
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if (polarity != SOFTPWM_NORMAL)
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polarity = SOFTPWM_INVERTED;
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for (i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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if ((pin < 0 && _softpwm_channels[i].pin >= 0) || // ALL pins
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(pin >= 0 && _softpwm_channels[i].pin == pin)) // individual pin
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{
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_softpwm_channels[i].polarity = polarity;
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}
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}
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}
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void SoftPWMSet(uint8_t pin, uint8_t value, uint8_t hardset) {
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if (hardset) {
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SOFTPWM_TIMER_SET(0);
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_isr_softcount = 0xff;
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}
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int8_t firstfree = -1; // first free index
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// If the pin isn't already set, add it
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for (uint8_t i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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if (_softpwm_channels[i].pin == pin)
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{
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// set the pin (and exit, if individual pin)
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_softpwm_channels[i].pwmvalue = value;
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if (pin >= 0) // we've set the individual pin
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return;
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}
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// get the first free pin if available
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if (firstfree < 0 && _softpwm_channels[i].pin < 0)
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firstfree = i;
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}
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if (firstfree >= 0) {
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// we have a free pin we can use
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_softpwm_channels[firstfree].pin = pin;
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_softpwm_channels[firstfree].polarity = _softpwm_defaultPolarity;
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_softpwm_channels[firstfree].outport = portOutputRegister(digitalPinToPort(pin));
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_softpwm_channels[firstfree].pinmask = digitalPinToBitMask(pin);
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_softpwm_channels[firstfree].pwmvalue = value;
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// _softpwm_channels[firstfree].checkval = 0;
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// now prepare the pin for output
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// turn it off to start (no glitch)
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if (_softpwm_defaultPolarity == SOFTPWM_NORMAL)
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digitalWrite(pin, LOW);
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else
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digitalWrite(pin, HIGH);
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pinMode(pin, OUTPUT);
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}
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}
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void SoftPWMEnd(uint8_t pin) {
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for (uint8_t i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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if (_softpwm_channels[i].pin == pin) {
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// Disable pin output
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digitalWrite(_softpwm_channels[i].pin, 1);
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pinMode(_softpwm_channels[i].pin, INPUT);
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// Flag as removed
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_softpwm_channels[i].pin = -1;
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}
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}
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}
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void SoftPWMEndAll() {
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for (uint8_t i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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// Disable pin output
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digitalWrite(_softpwm_channels[i].pin, 1);
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pinMode(_softpwm_channels[i].pin, INPUT);
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// Flag as removed
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_softpwm_channels[i].pin = -1;
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}
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}
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void SoftPWMSetFadeTime(int8_t pin, uint16_t fadeUpTime, uint16_t fadeDownTime) {
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int16_t fadeAmount;
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uint8_t i;
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for (i = 0; i < SOFTPWM_MAXCHANNELS; i++) {
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if ((pin < 0 && _softpwm_channels[i].pin >= 0) || // ALL pins
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(pin >= 0 && _softpwm_channels[i].pin == pin)) // individual pin
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{
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fadeAmount = 0;
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if (fadeUpTime > 0)
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fadeAmount = 255UL * (SOFTPWM_OCR * 256UL / (F_CPU / 8000UL)) / fadeUpTime;
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_softpwm_channels[i].fadeuprate = fadeAmount;
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fadeAmount = 0;
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if (fadeDownTime > 0)
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fadeAmount = 255UL * (SOFTPWM_OCR * 256UL / (F_CPU / 8000UL)) / fadeDownTime;
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_softpwm_channels[i].fadedownrate = fadeAmount;
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if (pin >= 0) // we've set individual pin
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break;
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}
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}
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}
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