RF interference

Forum 2005-2010 (read only) Hardware Interfacing
1

Hey All

I have two arduinos, one powered by a 9 V adapter, which has a blinking light and an RF transmitter which outputs 1 if the LED is on, 0 if the LED is off.

On the other arduino which is connected via USB, i have an RF receiver which outputs the value of whatever it is receiving to the serial monitor in Arduino.

Now no matter which baud rate I set, I seem to be either getting interference, or am not understanding how to decipher. HEAPS of data is coming in. I do use a wireless keyboard etc, but is there a way around this without cutting out every wireless device in the building?

Thanks Guys!

2

You have to tell us what type of transmitter so things like the interference from the wireless keyboard can be factored in. Also what sort of wireless keyboard.
Have you tried turning this off and seeing if it works?
However my bet is on the serial setup.

3

http://www.seeedstudio.com/depot/433mhz-rf-link-kit-p-127.html?zenid=f49e99923cbe15c8ca518574856d730c

That is the beauty there.

Receiver:
int incomingByte = 0;
int LED = 13;

void setup() {
Serial.begin(2400);
pinMode (LED, OUTPUT);
}

void loop() {
if(Serial.available() > 0) {
incomingByte = Serial.read();
Serial.println(incomingByte, DEC);
digitalWrite(LED, HIGH);
}
incomingByte = 0;
digitalWrite(LED, LOW);
}

Sender:
byte counter;
int LED = 13;

void setup() {
Serial.begin(1200);
pinMode(LED, OUTPUT);
counter = 0;
}

void loop() {
digitalWrite(LED, HIGH);
Serial.print(1);
delay(1000);
digitalWrite(LED, LOW);
Serial.print(0);
delay(1000);
}

I am using a Logitech keyboard and mouse, though unfortunately i can't do much without them.. Will have a go at turning them off while the arduinos are going in a second...

4

Nope, keyboard and mouse make no difference. Strange...

5

Ummm, I'm a little confused here. How exactly do you have those modules connected to your Arduino? Unless I'm missing something, they're not serial devices.

Normally, I would suggest using something like the VirtualWire library but AFAIK it hasn't yet been tested with those particular modules.

--Phil.

6

Oh, I see you've taken that code from the Sparkfun example. Wow, from what I'd read about those receivers/transmitters I wouldn't have thought you'd have been able to receive anything without any error correction etc.

--Phil.

7

The data on the page says:-

Receiver Data Output: High - 1/2 Vcc, Low - 0.7v

What voltage are you driving them with. If it is 5V and you are connecting it straight into the Arduino then there will not be enough to keep it high as it will only be at 2.5V for a logic one. It could be it is dithering at the threshold of the input.

8

Good point ( i think ) can you point me to any tutorials on separately powering the receiver? Is this the same for the transmitter?

Am getting back to VirtualWire to try get that going - the thread is here if you know anything in that area.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1240455887/0