Unable to find stable setting for my DX8 ppm input.

What steps will reproduce the problem?
Out of sync PPM generation.

1. Put Spektrum DX8 in programmable slave on all channel.
2- Connect Arduino pin 10 to Trainer port input.
3- Press Trainer switch when NO SLAVE switches to MASTER.
4- Go to monitoring screen and watch outputs ...All screwed up.

What is the expected output? What do you see instead?
Stable signals as per ISR usage from another code I downloaded.

What version of the product are you using? On what operating system?
Arduino Nano V3.0, pin 10.

Try this one ;)

/*
 PPM Tester (8 channel)
  By Kelly Perreault
INFORMATION:
  See ReadMe.txt for lots of info including I/O allocation.  
*/

#include "EEPROM.h"

char* Version[]={"Version", "  1.0   "};

// User adjustable settings
int pulseMin =420, pulseMid = 1250, pulseMax = 1250;            // PPM Pulse 
widths in uS

// Manual Timer, Interrupt Timer vars
unsigned char TimerStart = 0;    
int secflag = 0, minflag = 0;
int PPM_array[9];
int PPMFreq_uS = 22000;          // PPM frame length total in uS
int Fixed_uS = 400;              // PPM frame padding LOW phase in uS

// Assign analogue & digital I/O pins
int AI_Raw[7] = { 0, 1, 2, 3, 4, 5, 6 };                // actual analog input 
pins
int AI_Val[7];                                          // analogue input vars
int DI_Raw[10] = { 2, 3, 4, 5, 6, 7, 8, 9, 13, 11 };    // actual digital input 
pins
int DI_Val[10];                                         // digital input vars
unsigned char AI_pincount = 7;   // analogue pin count
unsigned char DI_pincount = 10;  // digital pin count
unsigned char outPinPPM = 10;    // PPM output pin (do not change - pin 10 tied 
to ISR

// Sub timing vars
int tick0 = 0, tick1 = 0, tick2 = 0, tick3 = 0, tick4=0, band=0,band2=0, 
currch=1;
unsigned char slowflag;

int ACC_PPM_length = 0;          // Pulse length current total, used to 
calculate sync pulse
int *PPM_pointer = PPM_array;
int PPM_len;

// *********************** Setup **************************
void setup() {

  // Setup Digital I/O
  pinMode(outPinPPM, OUTPUT);   // sets as output
  for(char i=0; i<DI_pincount; i++) { pinMode(DI_Raw[i], INPUT); }      // set digital inputs
  for(char i=0; i<DI_pincount; i++) { digitalWrite(DI_Raw[i], HIGH); }  // turn on pull-up resistors

   // Initialize PPM channel array
  char i=0;
 for(i=0; i<8; i++) { PPM_array[i] = pulseMin; }
 PPM_array[i] = -1;   // Mark end

  // Initialise ISR Timer 1 - PPM generation
  TCCR1A = B00110001;  // Compare register B used in mode 3
  TCCR1B = B00010010;  // WGM13 & CS11 set to 1
  TCCR1C = B00000000;  // All set to 0
  TIMSK1 = B00000010;  // Interrupt on compare B
  TIFR1  = B00000010;  // Interrupt on compare B
  OCR1A = PPMFreq_uS;  // PPM frequency
  OCR1B = Fixed_uS;    // PPM off time (lo padding)

  // Initialise ISR Timer 2 - Subroutine timing
  // Interrupt rate =  16MHz / (prescaler * (255 - TCNT2))
  // period [sec] = (1 / f_clock [sec]) * prescale * (255-count)
  //                (1/16000000)  * 1024 * (255-178) = .004992sec = 4.992mS
  TCCR2B = B00000000;   // Disable Timer2 while we set it up
  TCNT2  = 178;         // Reset Timer Count  (255-"178")
  TIFR2  = B00000000;   // Timer2 INT Flag Reg: Clear Timer Overflow Flag
  TIMSK2 = B00000001;   // Timer2 INT Reg: Timer2 Overflow Interrupt Enable
  TCCR2A = B00000000;   // Timer2 Control Reg A: Wave Gen Mode normal
  TCCR2B = B00000111;   // Timer2 Control Reg B: Timer Prescaler set to 1024

  // INFO ********************************************
  //1150 all except 1 for start at -108% to 38% (thr at 60%), 400 for array 1, band 250 , skip  1 
  //1170 all except 1 for start at -92% to 32%, 680 for array 1, band 250 , skip  1 
  //1150 all except 1 for start at -108% to 38% (thr at 45%), 600 for array 1, band 250 , skip  1
  //1139 all except 1 for start at -100% to 32%, 500 for array 1, band 250 , skip  1
  //940 all except 1 for start at -150% to 0% , 700 for array 1, band 230 , skip  1
  //940 all except 1 for start at -150% to 40% , 420 for array 1, band 100/2=50 , skip 1
 PPM_array[0] =  940; //Ax3 CH1
 PPM_array[1] =  420; //Ax2 CH2 default put to 1000=NO SYNC , 900=40%, 800=40% 700= 34%, 600=34% , 500=39%,  400=39% , 300=NO SYNC(toggle min or max) ,varies with AX1
 PPM_array[2] =  940; //THR  CH3
 PPM_array[3] =  940; //AIL  CH4
 PPM_array[4] =  940; //ELE  CH5
 PPM_array[5] =  940; //RUD  CH6
 PPM_array[6] =  940; //GER  CH7
 PPM_array[7] =  940; //AX1  CH8

}

// *********************** Main Loop **************************
void loop() { // Main loop

     // Read all input pins into AI var array 1
   for(byte i=0; i<AI_pincount; i++) {  
      AI_Val[i] = analogRead(AI_Raw[i]);
   } 

 if (tick0 >= 25) {             // Run these subs every 124.8mS
      tick0 = 0;
  }

  band=103; band2=band*2;

  // Generate slow changing flag
  if (tick4 <= band) {

    PPM_array[currch] = PPM_array[currch]+ 1; //ELE
  if ( currch <> 0 currch < 7  ) {
    PPM_array[currch+1] = PPM_array[currch+1]+ 1; //ELE
      }
  }
  if (tick4 > band && tick4 <= band2) {

     PPM_array[currch] = PPM_array[currch]- 1; //ELE
 if ( currch <> 0 && currch < 7  ) {
     PPM_array[currch+1] = PPM_array[currch+1]- 1; //ELE
  }

  if (tick4 > band2) 
  {
       PPM_array[currch]=PPM_array[currch]-7;
        currch= currch +1;
        tick4 = 0;  
  } 

  if (currch == 1) 
  {
      currch=2; //skip ch 2 - Ax2 - array 1
  }   

  if (currch >= 8) 
  {

       currch=0;
  } 

  if (tick1 <= 50) {
      slowflag = 0;     
  }

  if (tick1 >= 50 && tick1 <=100) 
  {
      slowflag = 1;

  }

  if (tick1 == 100)
  {
      tick1 = 0; 
  }

  // generate 1sec tick
  if (TimerStart == 0) {
      if (tick2 >= 160) {  // 1000mS
          secflag++;
          tick2 = 0;
      }

      if (secflag >= 60) {
          secflag = 0;
          minflag++;
      }  

      if (minflag >= 100) {
          minflag = 0;
      }
  }  

}

// *********************** TIMER 1 **************************
ISR(TIMER1_COMPA_vect) {
  PPM_len = *(PPM_pointer++);
  if(PPM_len > -1) {
    OCR1A = PPM_len;                        // Set pulse length
    ACC_PPM_length += PPM_len;              // Add pulse length to accumulator
  } else {
    PPM_pointer = PPM_array;                // Reset table position pointer
    OCR1A = PPMFreq_uS - ACC_PPM_length;    // Calculate final sync pulse length
    ACC_PPM_length = 0;                     // Reset accumulator
  }
}

// *********************** TIMER 2 **************************
ISR(TIMER2_OVF_vect) {
  tick0 = tick0 + 1;                        // update timing tick
  tick1 = tick1 + 1;                        // update timing tick
  tick2 = tick2 + 1;                        // update timing tick
  tick3 = tick3 + 1;                        // update timing tick
  tick4 = tick4 + 1;                        // update timing tick
  TCNT2 = 155;                              // reset timer cnt to 155 out of 255
  TIFR2 = 0x00;                             // timer2 int flag reg: clear timer overflow flag
}
Original issue reported on code.google.com by clearchr...@gmail.com on 25 Jan 2015 at 9:07
iw28 / generate-ppm-signal

Unable to find stable setting for my DX8 ppm input. #1
