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|   December 27, 2008 at 8:03 AM

Hi guys,
This one along with the matched receiver are not working for me :( I am using two Arduino boards to interface to them but cannot seem to receive anything. I followed every tutorial out there and nothing :( Please let me know if you had similar issues. If you got them to work and you have a hint please let me know also.

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|   August 24, 2009 at 1:15 PM

I had no problems getting this to work with the Arduino platform. I based my designs on the examples shown in Tom Igoe's _Making Thing Talk_ book and everything worked perfect. When sending data send some garbage first because the receiver takes a few bytes too tune in. It is also a good idea to send a little hash thingy with your data to verify there was no interference. I highly recommend Tom's book if you are using Arduino as he has some great diagrams and sample source code.

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|   December 28, 2008 at 3:14 AM

I played with this through a serial port and a max232 chip and it seemed to work perfectly up to 2400bps, but any higher and I had issues(I didn't use an antenna and only had 5 volts to the transmitter). Try connecting all ground and 5 volt pins on the receiver.

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|   December 31, 2008 at 9:54 AM

The problem is the receiver I got is spec'ed at 4800 bps... I'll try 2400bps and see what I get (although I think I may have tried that). Thanks for the response I'll post my results.

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|   December 31, 2008 at 2:04 PM

I have the 4800bps receiver as well and it will work at lower speeds. Something I noticed is that if I leave the system connected to power/ground, it will work after about 20 min(up to 2400 bps). If I just plug it in and try using it, I will get pretty bad data. Try using it at 300 or even 110 bps to make sure it is actually working.

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|   January  2, 2009 at 1:31 AM

OK final results:
At 110 bps, it still doesn't work!!! I actually got it to work by making a big antenna wire loop on the receiver, a smaller antenna loop on the xmitter and putting the xmitter loop inside the receiver antenna loop so that the two loops are in the same vertical plane. It worked flawlessly up to 4800bps but once the two loops moved I got total garbage LOL...

I wasted 5 full days (holiday vacation whenever ppl left) on something that costed < $10 :( Pretty sad. Going to give nRF2401A a shot next.

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|   January  2, 2009 at 1:33 AM

I forgot to thank all who responded. Really appreciated the help.

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|   January 17, 2009 at 7:27 AM

I had a micro upstairs sending the letter 'A' to the transmitter repeatedly with no antenna and the reciver downstairs connected to my pcs serial port with an antenna and it worked. i got some garbage in between but i'm going to do send a header some error checking in software to fix it.

my tip is to connect the reciver to the pc so you can see extacly what's been recived through hyperterminal. then you can play around with antenna length and stuff.

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|   January 29, 2009 at 7:27 PM

I was using a oscilloscope to look at the data onthe receiver end. When it worked it was inverted.. When I didnt have two loops of antennas inside of each other all i could see was garbage. Maybe I had bad units..!!!

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|   January 25, 2009 at 6:40 AM

actualy, make sure to use 23cm antenna for the receiver.
just a straight piece of wire will do.

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|   February 20, 2009 at 3:35 PM

I got the 315mHz transmitter/receiver pairs to work without difficulty, running from and to PICAXE 08M and 14M microprocessors. I used 23.8cm straight wire antennas on each. I'm glad the 315mHz version is available--I tried 433mHz and found that I am totally swamped in that frequency. Apparently 433mHz is in or very close to a legal ham range in the U.S. which can transmit at hundreds of times the power.

The description is somewhat misleading when it says, "Only one 315MHz transmitter will work within the same location." Only one can work at the same instant, but for datalogging, with message transmissions of a small fraction of a second, many can work in the same space provided that you understand and work around the possiblility that collisions may occur with resulting data loss--so transmit multiple times with varying gaps between transmissions.

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|   March 17, 2009 at 10:11 PM

Thanks for the information regarding "Only one 315MHz transmitter will work within the same location." I was not sure how to interpret that comment. And I want to prototype something that will require multiple transmitters!

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|   May 24, 2009 at 2:07 PM

I bought a set of these (315 @4800) to mess with. Haven't had very good luck. I was not able to get the receiver to work with the Arduino at all. The xmitter is connected to a Basic Stamp and set to transmit at 2400 baud. The receiver is connected to a Parallax Prop Plug and I'm monitoring at 2400 in Hyperterm. The range indoors is no better than about 20 ft with occasional errors. I can't get it working at 4800 baud. While far more expensive, I've had much better luck with bluetooth. Unless someone comes up with an easier and more robust way to connect these, they're pretty much useless for me.

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|   June 16, 2009 at 8:11 PM

Contrary to a lot of comments posted, these modules work just fine. Just remember that the receivers have automatic gain control and will increase their gain in order to find a signal. This means that the receiver will start to generate noisy output unless you transmit something about every 10mS. I dropped the antenna from my transmitter and signal integrity on the receiver improved - I left the antenna on my receiver. Further suggestions - put some filter caps across the power supply pins and integrate a preamble byte and a checksum. Have the receiver search for the preamble and verify the packet with the checksum.

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|   July 21, 2009 at 2:21 PM

It says it is using ASK which I assume means it has a constant carrier.

The datasheet is corrupted under foxit reader (and evince under linux) so I can't be sure it is turning anything on or off with data.

I have a pair and can't get them to work - there is no indication when it is supposedly transmitting, nor any carrier detect indication on the receiver.

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|   July 21, 2009 at 3:13 PM

To extend the prior post - there seems to be a MINIMUM frequency. Turning the transmitter ON constantly will only result in a sub-second pulse on the receiver.

By "4800 baud" it does not mean it can be connected as a UART serial link directly at that or any other speed. You can turn it on then send a series of pulses which have both a minimum and maximum width (that isn't very clear).

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|   August 28, 2009 at 3:03 PM

I've noticed with an oscilloscope precisely this, if you give the transmitter a 1 on its data line, the receiver only receives a pulse, it otherwise constantly outputs 0. A start bit with USART is a high to low transition so I don't know how this would interface with USART. I think it could still work. However the pulse width does not seem to be a constant value, I was getting between 80 to 200 microseconds or so. I'd start with a pretty low baud rate and hope that works...

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|   August 13, 2009 at 6:06 PM

I had difficulty getting correct/accurate data out of this chip. I stumbled upon this site and found it EXTREMELY useful. Now, 100% accurate data. I hated this transmitter until I found this site. Its for PICAXE but can be adapted

http://quicktrip.co.nz/jaqblog/index.php?option=com_idoblog&task=viewpost&id=25&Itemid=8

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|   September  4, 2009 at 2:23 PM

I got these bad boys working. Make sure to set your baud rate to the baud rate you are operating at in the Serial window of the Arduino software. I forgot to do this and was scratching my head but as soon as I did this I verified the data was correct!!!

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|   September 22, 2009 at 11:57 AM

This works perfectly! An antenna is a must! I successfully got this to work around 150 feet. You definitely can't just send data using this setup, you have to create your own checksum routine on the data bytes to weed out the interference.

Also, make sure receiver and transmitter are not sharing the same power supply or ground.

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|   September 22, 2009 at 11:59 AM

Also make sure you choose a baud rate under 2400 bps. I got the most success with this

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|   December 27, 2009 at 2:17 PM

I am having no luck getting the 315 MHz transmitter and receiver to work. I just want to see the data appear at the receiver using a scope. The transmitter and receiver are separated by about 2 inches with no antenna. I have the +5 and GNDs of the receiver attached to a stepup battery pack. I always see a 1 kHz square wave at 3.5Vpp. It doesn't matter if I am transmitting a '0', '1', or nothing at all. What am I doing wrong?

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|   January  4, 2010 at 1:31 PM

i have the 434Mhz version and i tried to link 2 arduinos using the KLP Walkthrough Tutorial, i get absolutely nothing fron the reciver with or without antena when the modules are as close as can be without touching. kinda hard to troubleshoot somthing with no output at all.

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|   January  5, 2010 at 2:41 PM

Lots of people are having problems getting these modules to work, I thought I'd post a link to a website that should help most to get these going. Here it is. http://letsmakerobots.com/node/5194

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|   January  5, 2010 at 2:50 PM

Forgot that there are people out there who use the Arduino, sorry. Here's another link with Arduino code. http://letsmakerobots.com/node/12336

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|   January  6, 2010 at 1:33 PM

Any word on FCC legality? It is my understanding that if we build a transmitting device, it is covered as a hobby part under FCC part 15 and therefore legal. However, one cannot purchase and use a transmitter that is not FCC part 15 certified. So, is this device legal?

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|   January  6, 2010 at 1:41 PM

Yes, these are FCC legal (or whatever you'd say:). The transmitting power is low enough that you don't need a license to use these. Also, the frequency band is in the "free" range, meaning that you can use it for any low power transmitter.