Jitter in radio signal when there is "motor.attach(2)" in the code

Projects Programming
1

Hi all,

I have got a radio transmitter and receiver and I want to control a motor with it. I can read the radio signal perfectly and I can also control the motor with a potentiometer. I use an Arduino MEGA 2560. The motors are actually brushless motors with ESC (Electronic Speed Controller)

The problem is if I put the line

motor.attach(2);

There is automatically jitter in the radio signal. The overall code is (it reads the radio signal and maps it to [0 - 100])

#include <Servo.h>

#define MAX_1 2669
#define MIN_1 1257

#define MAP_RADIO_HIGH 100
#define MAP_RADIO_LOW 0



unsigned long ch1=0;  
Servo motor;


void setup()
{
motor.attach(2);

pinMode (10, INPUT);

Serial.begin(9600);
Serial.println("Done with setup");
}



void loop()
{
// get the values  
ch1  = pulseIn (10, HIGH, 100000); 
ch1 = MAP_RADIO_HIGH - map(ch1, MIN_1, MAX_1, MAP_RADIO_LOW, MAP_RADIO_HIGH);

//print the values
Serial.print ("ch1 ");
Serial.println (ch1);

delay(20);
}

If I comment the line

motor.attach(2);

there will be no jitter. And the battery for the motors is not even plugged so it's not an interference with power problem.

Any advice would be greatly appreciated, :wink:
Thanks!

2

If by jitter you mean pluseIn() reporting odd values then yes with servo running that may happen as servo is interrupt and timer driven.

Mark

3

If by jitter you mean pluseIn() reporting odd values then yes with servo running that may happen as servo is interrupt and timer driven.

Yes this is what I mean. Is there any way to deal with this problem?

4

One solution is to use interrupts and therefore the pulseIn() is not needed.

Exemple with lots of documentation here => RCArduino: How To Read Multiple RC Channels

5

If you still need help - I've written a library for RC-Receiving which works quite well (I'm steering a quadcopter with it).
If you're still interested, write me a pm or so.

6

You don't say which transmitter/receiver you are using. ESCs put out loads of RF
interference, if you have a cheap receiver then you'll pick up lots of noise.

You need a correctly designed antenna, as far from the ESCs and motors as poss,
and a selective receiver with a decent front-end.

7

Hi,

The problem was resolved some time ago:

One solution is to use interrupts and therefore the pulseIn() is not needed.
Exemple with lots of documentation here => RCArduino: How To Read Multiple RC Channels

Works flawlessly. My transmitter/receiver is a Turnigy 6X FHSS 2.4ghz (30$ on hobbyking).