File content as of revision 1:3649456c67ef:

#include "mbed.h"
#include "PPMOut.h"

PpmOut::PpmOut(PinName pin, uint8_t channel_number): ppm(pin) {
    if(channel_number > MAX_CHANNELS){
        this->channel_number = MAX_CHANNELS;
    }
    this->channel_number = channel_number;
    resetChannels();
    pulse_out = 1;
    ppm = pulse_out;
    current_dot = 0;
    timeout.attach_us(this, &PpmOut::attimeout, FRAME_LEN);
}

void PpmOut::setChannel(int channel_no, uint16_t value) {
    //__disable_irq();     // Disable Interrupts
    if(channel_no > channel_number-1){
        return;
    }
    if(value > MAX_CHANNEL_VALUE){
        value = MAX_CHANNEL_VALUE;
    }
    dots[channel_no*2] = CHANNEL_SYNC;
    dots[channel_no*2+1] = CHANNEL_PAD_SYNC + value;

    setFrameSync();
    //__enable_irq();     // Enable Interrupts
}

void PpmOut::setFrameSync(){
    uint16_t sum_channels = 0;
    for(uint8_t channel = 0; channel < channel_number; channel++) {
        sum_channels += dots[channel*2+1];
    }
    sum_channels += channel_number*CHANNEL_SYNC;
    dots[channel_number*2] = CHANNEL_SYNC;
    dots[channel_number*2+1] = FRAME_LEN - CHANNEL_SYNC - sum_channels;
}

void PpmOut::attimeout() {
    pulse_out = !pulse_out;
    ppm = pulse_out;
    
    timeout.attach_us(this, &PpmOut::attimeout, dots[current_dot]);
    current_dot++;

    if(current_dot == channel_number*2+2) { // 2 for FRAME_SYNC
        current_dot = 0;
    }
}

void PpmOut::resetChannels() {
    int8_t channel;
    
    current_dot = 0;
    memset(dots, 0x00, DOTS);
    for(channel = 0; channel < channel_number; channel++) {
        dots[channel*2] = CHANNEL_SYNC;
        dots[channel*2+1] = CHANNEL_PAD_SYNC;
    }
    setFrameSync();
}