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46  Forum 2005-2010 (read only) / Frequently-Asked Questions / XBEE how does it work? on: December 13, 2010, 11:31:51 am
Today I discovered the XBEE and since I play with RC cars I asked myself how it works.

Can I make a panel with a joystick, potmeters and so on and control my car with it? I would need one Arduino board with a XBEE on it and another XBEE in my car. Or do I also need another Arduino board in my car?

It would be nice if I could use the remote XBEE to give the PWM signals to the car and give sensor data (if applicable) back to the base where it can be processed and be turned into steering commands if needed. This way a second board isn't necessary.
(it would be a wireless extension of my Arduino pins)

Leo
47  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: constant for delay on: December 16, 2010, 02:28:02 pm
Thanks,

Now it works!
48  Forum 2005-2010 (read only) / Frequently-Asked Questions / constant for delay on: December 16, 2010, 01:03:26 pm
Hi,

I'm trying to make some led light walk like on Kit.

I'm trying to use a constant for the delay so when I have to change the interval I don't have to change a large number of delay values.

This is the code so far but compiling this already gives trouble.

Code:
void setup()
{
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);  
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  const int val = 30;
}
 
void loop()
{
  digitalWrite(2, HIGH);
  delay (val);
}
After compiling I'm told "'val' was not declared in this scope". I think I just did???

Anybody know how to do it?

Thanks,
49  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Why Do I Need A Resistor on: December 11, 2010, 01:54:32 pm
A led has a fixed pressure (voltage) drop. For the remaining voltage a resistor is used, if choosen correctly it restricts the current flowing through the led.

50  Forum 2005-2010 (read only) / Frequently-Asked Questions / first post on: December 11, 2010, 05:33:57 am
Hi,
51  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: unable to control a servo with Arduino on: December 11, 2010, 09:24:46 am
You guys rule!

A have connected a 4 cell NiMH receiver pack to the servo and it's working fine now.

Thanks,

Edit:
This is the code I used to control 2 servos.

// Controlling servo positions using potentiometers
// by Michal Rinott, edited by Leo Groeneveld

#include <Servo.h>
 
Servo myservo1;  // create servo object to control servo1
Servo myservo2;  // create servo object to control servo2
 
int potpin1 = 0;  // analog pin used to connect the potentiometer
int val1;         // variable to read the value from the analog pin
int potpin2 = 1;  // analog pin used to connect the potentiometer
int val2;         // variable to read the value from the analog pin
 
void setup()
{
  myservo1.attach(9);  // attaches servo1 on pin 9 to the servo object
  myservo2.attach(10); // attaches servo2 on pin 10 to the servo object
}
 
void loop()
{
  val1 = analogRead(potpin1);            // reads the value of the potentiometer (value between 0 and 1023)
  val1 = map(val1, 0, 1023, 0, 179);     // scale it to use it with the servo (value between 0 and 180)
  myservo1.write(val1);                  // sets the servo position according to the scaled value
  int sensorValue1 = analogRead(potpin1);
  val2 = analogRead(potpin2);            // reads the value of the potentiometer (value between 0 and 1023)
  val2 = map(val2, 0, 1023, 0, 179);     // scale it to use it with the servo (value between 0 and 180)
  myservo2.write(val2);                  // sets the servo position according to the scaled value
  int sensorValue2 = analogRead(potpin2);
  delay(15);                             // waits for the servo to get there
}

Why are these statements "int sensorValue2 = analogRead(potpin2);" in the sketch? I don't understand what they are doing.
52  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: unable to control a servo with Arduino on: December 11, 2010, 06:38:36 am
Thanks for the quick replies!

I can't find the specs (box) from the servo but it's a high torque mini servo with MG.

I have a seperate supply (12V 3A DC) but I dare not use it because I don't know the polarity of the connector on the board. Is the pin in the middle +?

What should I do with the servo.h tab?

53  Forum 2005-2010 (read only) / Frequently-Asked Questions / unable to control a servo with Arduino on: December 11, 2010, 05:34:34 am
Hi,

I have received my Arduino Mega1280 clone this week and started playing with it. Yesterday I tried to control a servo with a potmeter but just got the servo to make a high pitch noise and causing the laptop to crash after connecting the servo. (I had to restart the laptop to be able to upload sketches to the Arduino).

After adding some lines to be able to track the potsettings on screen I found out that the potmeter works fine.
Replacing the servo with a resistor and led showed that the intensity of the light changes with the potvalue so my output seems to work ok also.

I have used this sketch.

// Controlling a servo position using a potentiometer (variable resistor)
// by Michal Rinott <http://people.interaction-ivrea.it/m.rinott>;

#include <Servo.h>

Servo myservo;  // create servo object to control a servo

int potpin = 0;  // analog pin used to connect the potentiometer
int val;    // variable to read the value from the analog pin

void setup()
{
 myservo.attach(10);  // attaches the servo on pin 9 to the servo object
  Serial.begin(9600);
}

void loop()
{
 val = analogRead(potpin);            // reads the value of the potentiometer (value between 0 and 1023)
 val = map(val, 0, 1023, 0, 179);     // scale it to use it with the servo (value between 0 and 180)
 myservo.write(val);                  // sets the servo position according to the scaled value
 int sensorValue = analogRead(potpin);
 Serial.println(sensorValue, DEC);
 delay(15);                           // waits for the servo to get there
}

What could be causing the trouble? I think I should add the servo.h tab but where can I find it, and what is it?

Regards,

Leo
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