315 MHz Transmitter/Receiver (WRL-08945 or WRL-08947) help

I am stumped and after about 12 hours of being stuck I am asking for some help. I have 2 Arduino mini pro’s (5v) and I just got a 315 Transmitter and receiver http://www.sparkfun.com/commerce/produc … ts_id=8945 and http://www.sparkfun.com/commerce/produc … ts_id=8947. I have been trying to get them to communicate and I have failed. I have found every tutorial out there and wired them up the exact same and used their code. So I am asking for help if anyone has dealt with this situation before or has any tips how to debug.

Here is where I am now, exact same setup and I am using this code.

http://www.sparkfun.com/datasheets/RF/K … hrough.pdf

I can get the arduino’s talking to each other by connecting tx (mini 1) to rx (mini 2) and connect their grounds to each other. So I know the code is functional. I have verified the power is reaching both transmitter and receiver. And since I ordered 2 of these units I have switched them out.

Any help would could save my sanity.

now it’s 2:45 AM.

What are you trying to send back and forth between them? How much data? What is your baud rate?

I used multiple examples which varied from 1200 to 4800. I have the up to 4800 models. I am a programmer so the code is correct and I can verify it’s functioning correctly when I hook up usb and either monitor or send data. My sending data was either a constant stream of letters and numbers or just sending 1 digit with a small delay.

I am not new to Adruino or the IDE, where I lack experience is electronics. I have checked and double checked the set ups and they are the exact same(with some examples adding resistors or capacitors). I would love to use these but at the moment I have 2 pair sitting in my nice red SF box collecting dust.

I was thinking about hooking the rx line directly to the analog pin to monitor and confirm data or lack of.

I will take any advice or debugging tips you have.

Thanks.

I really have no idea. It sounds like you are doing everything right. Try what you said and see where that gets you.

After another weekend, I still cannot get these little things to work???

I sent the RX into an analog port and I can see a noticeable change when turning on and off the TX on the other arduino so I can confirm that data is indeed being transmitted but I am still not receiving anything, not even garbage.

I plugged the RX directly into my FTDI Basic Breakout and I cannot receive any data. Nothing.

I also tried putting the TX and RX modules going into the same arduino. Nothing.

I am stumped, data is flowing but no data is being processed.

I will send $20 to anyone who can help me!

Did you look at the RF Receiver output with an O’scope?

These RF units use OOK modulation. Are you sending a few sync characters to allow the receiver to settle in on the TX signal?

I don’t have an O’scope, I was using the analog pin as a makeshift one.

My sending data would send a character with a 250 millisecond pause. I also tried sending a string like

Serial.print(“HHH”);

But nothing seamed to work.

Serial.print(“HHH”);

a ‘H’ in binary is 01001000, so there are only two bits as logic high and 6 bits logic low. Try instead the character ‘U’ which is 01010101 in binary and also try sending more than 3 characters. Did you look up and read about OOK modulation?

Since you don’t have a O’scope try sending a continuous stream of "U"s for about 10 seconds then a continuous stream of DEL (0x7F) and monitor the RX output with a Voltmeter. There should be a change in Voltage between sending the 'U’s verses sending the DELs.

I have been looking into ASK and OOK modulation.

I have my loop function just spitting out U’s and still nothing over the receiver. I am wondering if I should try the 434 MHz. boards. I can still see a noticeable voltage drop on different data so the transmitters seem to be working, Could this be a grounding issue or something like that?

void loop()
{
   Serial.print("U");
}

Any more tips wold be awesome.

Thank you all for helping… I am still stumped as to why it has not worked with normal Serial or even NewSoftwareSerial but I found VirtualWire

http://letsmakerobots.com/node/12336

I swear I have tried this before but since it was most likely 2am. I did not change the RX pin in the sketch. I uploaded the sketch and booya, it worked like a dream. I was about to buy a microwave just to place these little guys inside and watch the fireworks. So to anyone who buys these transmitter pairs, YOU HAVE TO use or at least try virtualwire.

P.S. Sparkfun rules!

Glad to see you did get the RF link working.

I took a look at the VW code and wow, that is not the simple approach but it is what’s needed for a reliable RF link using OOK.

Nice! It’s always something simple like that. I was beating my head against the wall trying to get a button input to work once only to realize I had crossed GND and 5V. Silly mistake and I troubleshot it for an hour. Sigh.

I am 20 times happier today then yesterday because it works, sadly I have wasted… I should say invested around 15 hours into this…

SFE-TS-Robert and waltr,

THANK YOU

eh, I didn’t do anything.