CPPM Library for Arduino

[jmparatte]

I have written a library for Arduino to interface the CPPM signal of a RC receiver. With it, I can control a small motorized engine with a RC transmitter.

My engine is driven by 2 small dc wheels/motors. Left and right wheels/motors are controlled by PWM pin 5 and 6. The ELEV stick controls the speed and sens of deplacement. The RUDD stick controls the left and right turn and rotation.

The library is documented and explained here: CPPM Library for Arduino

To French readers: La librairie est documentée et expliquée en français ici:  Arduino - CPPM Library

[Jimbow]

Hello!

I Try your code, and it's dosen't work!!!!

Code: [Select]

#include "CPPM.h"

// your code...

void setup(void)
{
  pinMode(11,INPUT);
  Serial.begin(9600);
  CPPM.begin();
}

void loop(void)
{
  if (CPPM.synchronized())
  {
    int throttle = CPPM.read(CPPM.THRO);
    digitalWrite(11, !digitalRead(11));    //LED
    Serial.println(throttle);
  }
}
I see nothing in monitoring

Code: [Select]

#include "CPPM.h"
I do this because i put .cpp and .h in the same directory

I change in .h the pin interrupt like this because i use an AtMega32u4: INT0 is on pin 5

Code: [Select]

#define CPPM_ICP1 5

I use an Teensy v2:
My board : https://www.pjrc.com/store/teensy.html
Doc : http://www.atmel.com/images/doc7766.pdf

And my RC is : FRSKY D4RII (It's working on my Naze32 ! )


Thx for help

[jmparatte]

Hi Jimbow,

I've watched the specifications of the receiver FRSKY D4RII.
It differs from Orange R615X in 2 points:

1/ The synchronization is based on falling edge.
2/ The frame rate is 18ms. So the max number of servos is restricted to 1st 6 of 8 channels (as explained in last red note of manual).

It's why my CPPM library can't synchronize with FRSKY at moment.
I must write some modifications to my library.

At moment, I doesn't own a FrSky equipment, only Orange receivers and Spektrum transmitters.
If somebody based in Switerland can lend me a FrSky D4RII and a transmitter, I could update my library.

You can also try another library, for example: https://github.com/claymation/CPPM

[Jimbow]

Hi!

I've read your code ^^ and now it 's working!

In first i have do a mistake, interrupt pin (AtMega32u4) for timer 1 is not in pin 5 but in pin 22 ^^

In Seconde, i see in your code :
Line 99

Code: [Select]

if (CPPM.sync3 < (610 - 16) || CPPM.sync3 > (643 + 16))

I think it's with pulse for a Spektrum (300us) but for FRSKY D4RII it's 400us !

I modified a little your code and i have add in CPPM.h:

Code: [Select]

#ifndef FRSKY_D4RII
#define WITH_SYNC_PULSE 800 //400us for 0.5us tick timer (16MHz/2)
#define MAX_GAP_PULSE 5088 // 2544 us 
#else
#define WITH_SYNC_PULSE 300 //300us
#define MAX_GAP_PULSE 5088 // 2544us for 0.5us tick timer (16MHz/2)
#endif 

I have modified the line 99:

Code: [Select]

if (CPPM.sync3 < WITH_SYNC_PULSE - 30 || CPPM.sync3 > WITH_SYNC_PULSE + 30)

And the line 113:

Code: [Select]

if(CPPM.sync2 > MAX_GAP_PULSE) // gap pulse ?


note:
I live in france in Haute Savoie not far from Annemasse, i think you are from geneva ^^

[jmparatte]

Thank you Jimbow for your help.
I will study the AtMega32u4 that I don't know currently.
And integrate your corrections.
And the write() function to generate a CPPM Stream (Arduino pin 9).
I have also written a ATtiny85 CPPM decoder for 4 servos.

note: I live in Neuchâtel. Annecy is not so far.

[jmparatte]

I've published a new enhanced/reworked revision today.

[markfrasca]

Thanks. Can you explain how to use it with FRSKY receivers?

[markfrasca]

OK got this code working with my FrSky D8R-XP receiver. Question is how do I send CPPM output to pin 9?