#ifndef _PPMEncoder_h_

#define _PPMEncoder_h_

#if defined(ARDUINO) && ARDUINO >= 100

#include "Arduino.h"

#else

#include "WProgram.h"

#endif

template<uint8_t numChannels = 8>

class PPMEncoder {

public:

const uint16_t minValue;

const uint16_t maxValue;

const uint16_t pulseLength;

const uint16_t frameLength;

PPMEncoder() : minValue(1000), maxValue(3000), pulseLength(500), frameLength(22500) {}

PPMEncoder(const uint16_t minValue, const uint16_t maxValue, const uint16_t frameLength, const uint16_t pulseLength)

: minValue(minValue), maxValue(maxValue), pulseLength(pulseLength), frameLength(frameLength) {}

void setChannel(uint8_t channel, uint16_t value) {

channels[channel] = constrain(value, minValue, maxValue);

};

void setChannelPercent(uint8_t channel, uint8_t percent) {

percent = constrain(percent, 0, 100);

setChannel(channel, map(percent, 0, 100, minValue, maxValue));

};

void begin(uint8_t pin, boolean inverted = false) {

cli();

// Store on/off-State in variable to avoid another if in timing-critical interrupt

onState = (inverted) ? HIGH : LOW;

offState = (inverted) ? LOW : HIGH;

pinMode(pin, OUTPUT);

digitalWrite(pin, offState);

state = true;

elapsedUs = 0;

currentChannel = 0;

outputPin = pin;

for (uint8_t ch = 0; ch < numChannels; ch++) {

setChannelPercent(ch, 0);

}

TCCR1A = 0;

OCR1A = 100;

TCCR1B = (1 << WGM12) | (1 << CS11);

TIMSK1 = (1 << OCIE1A); // enable timer compare interrupt

sei();

};

void interrupt() {

TCNT1 = 0;

if (state) {

digitalWrite(outputPin, onState);

OCR1A = pulseLength * 2;

} else {

digitalWrite(outputPin, offState);

if (currentChannel >= numChannels) {

currentChannel = 0;

elapsedUs = elapsedUs + pulseLength;

OCR1A = (frameLength - elapsedUs) * 2;

elapsedUs = 0;

} else {

OCR1A = (channels[currentChannel] - pulseLength) * 2;

elapsedUs = elapsedUs + channels[currentChannel];

currentChannel++;

}

}

state = !state;

};

private:

int16_t channels[numChannels]{};

uint16_t elapsedUs{};

uint8_t currentChannel{};

byte outputPin{};

boolean state{};

uint8_t onState{};

uint8_t offState{};

};

#endif