Created
May 26, 2016 13:11
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/* | |
* PPM generator originally written by David Hasko | |
* on https://code.google.com/p/generate-ppm-signal/ | |
*/ | |
//////////////////////CONFIGURATION/////////////////////////////// | |
#define CHANNEL_NUMBER 12 //set the number of chanels | |
#define CHANNEL_DEFAULT_VALUE 1500 //set the default servo value | |
#define FRAME_LENGTH 22500 //set the PPM frame length in microseconds (1ms = 1000µs) | |
#define PULSE_LENGTH 300 //set the pulse length | |
#define onState 1 //set polarity of the pulses: 1 is positive, 0 is negative | |
#define sigPin 10 //set PPM signal output pin on the arduino | |
/*this array holds the servo values for the ppm signal | |
change theese values in your code (usually servo values move between 1000 and 2000)*/ | |
int ppm[CHANNEL_NUMBER]; | |
void setup(){ | |
//initiallize default ppm values | |
for(int i=0; i<CHANNEL_NUMBER; i++){ | |
ppm[i]= CHANNEL_DEFAULT_VALUE; | |
} | |
pinMode(sigPin, OUTPUT); | |
digitalWrite(sigPin, !onState); //set the PPM signal pin to the default state (off) | |
cli(); | |
TCCR1A = 0; // set entire TCCR1 register to 0 | |
TCCR1B = 0; | |
OCR1A = 100; // compare match register, change this | |
TCCR1B |= (1 << WGM12); // turn on CTC mode | |
TCCR1B |= (1 << CS11); // 8 prescaler: 0,5 microseconds at 16mhz | |
TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt | |
sei(); | |
} | |
void loop(){ | |
/* | |
Here modify ppm array and set any channel to value between 1000 and 2000. | |
Timer running in the background will take care of the rest and automatically | |
generate PPM signal on output pin using values in ppm array | |
*/ | |
} | |
ISR(TIMER1_COMPA_vect){ //leave this alone | |
static boolean state = true; | |
TCNT1 = 0; | |
if (state) { //start pulse | |
digitalWrite(sigPin, onState); | |
OCR1A = PULSE_LENGTH * 2; | |
state = false; | |
} else{ //end pulse and calculate when to start the next pulse | |
static byte cur_chan_numb; | |
static unsigned int calc_rest; | |
digitalWrite(sigPin, !onState); | |
state = true; | |
if(cur_chan_numb >= CHANNEL_NUMBER){ | |
cur_chan_numb = 0; | |
calc_rest = calc_rest + PULSE_LENGTH;// | |
OCR1A = (FRAME_LENGTH - calc_rest) * 2; | |
calc_rest = 0; | |
} | |
else{ | |
OCR1A = (ppm[cur_chan_numb] - PULSE_LENGTH) * 2; | |
calc_rest = calc_rest + ppm[cur_chan_numb]; | |
cur_chan_numb++; | |
} | |
} | |
} |
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