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Author Topic: Turnigy 9x RC and 8ch receiver  (Read 1043 times)
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Hi, I am building my own quadrocopter, but I have one problem. When I connect receiver directly to regulator and control it with RC, it works normally. But if I connect it via Arduino, then it sometimes start to rotate when it shouldn't rotate or rotate with about 1s breaks. I searched on google but I can't find the basic receiving and sending PPM to regulators and I don't want any completed solution because I want to create my code according to my needs. And I am using Arduino Mega 2560 R3.

My basic code for receiving PPM and sending to regulators:

Code:
#include <Servo.h>

Servo esc1;
Servo esc2;
Servo esc3;
Servo esc4;

int esc1_pin = 10;
int esc2_pin = 11;
int esc3_pin = 12;
int esc4_pin = 13;

int ch1;
int ch2;
int ch3;
int ch4;
int ch5;
int ch6;
int ch7;
int ch8;

void setup() {
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(4, INPUT);
  pinMode(5, INPUT);
  pinMode(6, INPUT);
  pinMode(7, INPUT);
  pinMode(8, INPUT);
  pinMode(9, INPUT);
 
  esc1.attach(esc1_pin);
  esc2.attach(esc2_pin);
  esc3.attach(esc3_pin);
  esc4.attach(esc4_pin);

  delay(1000);

//Serial.begin(115200);
}

void loop() {

  ch1 = pulseIn(2, HIGH, 25000);
  ch2 = pulseIn(3, HIGH, 25000);
  ch3 = pulseIn(4, HIGH, 25000);
  ch4 = pulseIn(5, HIGH, 25000);
  ch5 = pulseIn(6, HIGH, 25000);
  ch6 = pulseIn(7, HIGH, 25000);
  ch7 = pulseIn(8, HIGH, 25000);
  ch8 = pulseIn(9, HIGH, 25000);

  esc1.writeMicroseconds(ch3);
  esc2.writeMicroseconds(ch3);
  esc3.writeMicroseconds(ch3);
  esc4.writeMicroseconds(ch3);
  delay(20);
}

This is my basic program for just receiving and sending pulses but it does I wrote above. Does anybody know, where is the problem? I tried to simulate it via sending data to serial port instead of to regulators and checking in console and it was ok. I suppose that there may be problem with delay but I changed it and didn't helped. Unfortunatelly I don't have osciloscope so I can't check the output pulses. So if anybody where is the problem it would be helpful, other code isn't problem, just the receiving and sending signals doesn't work.
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Hi Kyong.

I'm not sure you can read the 8 channels with pulseIn() function.
I think pulseIn(pin, HIGH, time) waits a HIGH from a LOW. You read channel 1, when channel 1 goes to LOW you read channel 2 but in these moment channel 2 is HIGH already. Then pulseIn() for channel 2 is waiting for a LOW and it arrives one cycle (about 20 ms) later. So you are reading every channel every 8 cycles.

Also servo library uses interrupts and I think it causes errors in pulseIn() readings.

You can read some info from my blog http://cuadricopterodiyarduino.blogspot.com.es
But I'm sorry, it's in spanish.
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Thanks for info unfortunatelly I don't understand spanish. I will try to use a translator on it. If the interrupts are problems how to solve it? Is it possible to solve it without parsing the whole PPM from receiver?
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I don't know how people solve it or even if they have or not this problem. I think a lot of people have this problem with interrupts but they don't know they have it.

Although my project of quadcopter isn't finished I have developed a preliminary solution for this. Besides use a translator to understand all entries you can download the codes for it from

http://cuadricopterodiyarduino.blogspot.com.es/2012/07/leer-emisora-rc-parte-2.html

and

http://cuadricopterodiyarduino.blogspot.com.es/2012/08/control-motores-parte-2.html
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