SparkFun Electronics - RF Link 4800bps Receiver

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RF Link 4800bps Receiver - 434MHz

sku: WRL-08950

Description: Sold as a receiver only. This receiver type is good for data rates up to 4800bps and will only work with the 434MHz transmitter. Multiple 434MHz receivers can listen to one 434MHz transmitter.

This wireless data is the easiest to use, lowest cost RF link we have ever seen! Use these components to transmit position data, temperature data, even current program register values wirelessly to the receiver. These modules have up to 500 ft range in open space. The receiver is operated at 5V.

We have used these modules extensively and have been very impressed with their ease of use and direct interface to an MCU. The theory of operation is very simple. What the transmitter 'sees' on its data pin is what the receiver outputs on its data pin. If you can configure the UART module on a PIC, you have an instant wireless data connection. Data rates are limited to 4800bps. The typical range is 500ft for open area.

This receiver has a sensitivity of 3uV. It operates from 4.5 to 5.5 volts-DC and has digital output. The typical sensitivity is -103dbm and the typical current consumption is 3.5mA for 5V operation voltage.

Features:

434 MHz Operation
500 Ft. Range - Dependent on Transmitter Power Supply
4800 bps transfer rate
Low cost
Extremely small and light weight

Documents:

KLP Walkthrough Tutorial
Good AVR Tutorial
Receiver Datasheet
Another Very Helpful AVR Tutorial - Thanks Eric Forkosh!

Pricing

	996 in stock backorder allowed

$5.95	price
$5.36	10-99 (10% off)
$4.76	100+ (20% off)

	quantity

click on image to enlarge

Comments

15 comments

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	by AnthonyNBL +1.3 \| Feb 8, 2009 at 6:48pm –0.23
It does not work good. When the transmitter DATA IN is in LOW level, the receiver DATA OUT holds in LOW level as well. ok! But if the transmitter DATA IN is in HI level, the receiver starts to flick. It NEVER holds on HI level. Is this normal? The .PDF is very poor.

	by zklapow +1.7 \| Mar 8, 2009 at 9:58pm –0.23
when is this going to be in stock?

nevdull

+1.9

| Jul 25, 2009 at 12:13am

+0.23

Could anyone that has gotten this to work with an AVR kindly post how you did it? I've purchased two transmitters (WRL-08946 434MHz and one receiver (WRL-08950) and I have not been able to get them to communicate. I've tried both tx'ers (one at a time) and nothing. I know my USART communication is ok as a) I've used this code on several other projects and it's fine, and b) when i hardwire connect the TX from one ATmega328p to the RX of the other ATmega328p and open my console on the RX end, i can see the communication perfectly. I've checked, double checked the wiring and connections. I've followed two separate tutorials using these devices.

Can anyone suggest how to get these working?

SomeoneElse

+1.4

| Jul 27, 2009 at 10:13am

On the transmitter page, someone posted an overview of how to deal with the static.

ErieRider: Duplicating my post... 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.

	by lobstertail +2.3 \| Dec 6, 2009 at 12:45am 0
I tried to use the code from the SparkFun tutorial, but it didn't work. In any case, I found this site: link

	by lobstertail +2.3 \| Dec 6, 2009 at 12:47am 0
Also, I had to #include , but it works.

	by lobstertail +2.3 \| Dec 6, 2009 at 12:49am 0
Gah! I keep hitting submit instead of preview! I meant to say that I had to #include SoftwareSerial.h to get it to compile.

BoBlepepeur

| Dec 15, 2009 at 7:44am

If that can help some people...

I buy this to use with a pic18f from microchip with a mikroe board, after one week, i go to be crazy because i get nothing out of the data pin.

I found the right doc and I read that the high level is 0.7*Vdd so ~3.5V -> 1 and 0V -> 0, but the pic don't get it at this level.
So I have to put one transistor command with the output data pin and powered with 5V.
And with that it's working !! UART don't work good with my case, so i use Manchester coding ( I think it is best ), and no problem now !

http://www.8051projects.net/e107_files/public/1244115299_7657_FT20623_transmitt433mhz.pdf

http://www.8051projects.net/e107_files/public/1244115299_7657_FT20623_recieverrxd1433mhz.pdf

Good luck ;-)

SilverGhost

+2.5

| Jan 21, 2010 at 6:57am

Hi, I just received one of these modules yesterday and am unable to receive anything. (434MHz model)

I connect the 2x +5V, 2x GND of the receiver on a breadboard, a 20cm wire as an antenna, and try to monitor activity on pin 2 (data pin) and pin 3 (Test) using a MSO19 USB Mixed Signal Oscilloscope (sold on SparkFun).

Here, I expected to get some garbage from surrounding RFI, but I have a flat 0 using the oscilloscope function and with the logic analyzer portion, sometimes I got 1 sometimes 0, but it never changes, like if the output was "tristated" or "floating".

I then tried to use an old project to send some data (it uses the TX that matches with this receiver), and I know this project works as it sends X10 RF code, and light my living room halogen up.

Then again, nothing on the receiver data pins.

Shall I assume that the RX module is defective, did you have problems with them recently ?

Thanks in advance.

	by Tinsnips +1.3 \| Mar 13, 2010 at 2:54pm 0
SilverGhost, Did you manage to get this working? If so, what was the problem? I'm not getting anything out of the receiver, not even the garbage data... Any suggestions are very welcome.

Waif

+1.5

| Mar 21, 2010 at 4:10pm

Using Pic to Pic serial communications with these I can't seem to push it past 1200bps. It seems pretty stable there however. Using a DSO Scope I captured and compared the out going serial data from the pic and the output from the receiver module. They look alright at 1200bps but any faster and they go out of sync. 15 to 58 percent shorter pulses on the receiver end. Explains why it doesn’t work at high speed. Example: 1 bit on transmitter micro pin = 208us where as 1 bit on receiver output is 88us... BAD! Running at 4800bps.
The transmitter end also takes a little bit to trigger so it could also be on that end of things. Overall it works for what I need it to

zachtos

+2.1

| Apr 19, 2010 at 11:54am

I cant' get this receiver to work right. I get constant noise when not transmitting. I saw that you are supposed to get a signal every 10ms or it will go crazy. I am just using this to count pulses every 50ms, I can't go faster because of harware limitation issues. Is there a way around this? Some of them get 1017 on analog input for a signal found, while other receivers only get 1014. I get spikes during static/no signal that peak all the way to 1019. I have the data pins soldered together, the data pins soldered together, the power, the ground/antenna. So only 3 wires go to the micro, power/ground/data, and one wire outside to antenna. no capacitors or the like, except on the micro's 5V power supply.

	by guitarbaka +1.3 \| Jun 7, 2010 at 10:45pm 0
I finally got this to work with my AVR - MEGA644PA. The trick is to setup a small delay between transmissions in the while loop. In other words, when sending data from the transmitter, I have a delay of 2ms before sending data again. This sends data about every 10 seconds. When I had a delay of 100ms, I was never able to send anything. I am using 2400 baud.

	by johnfrank +1.1 \| Jul 7, 2010 at 7:18pm 0
transmitter seems to work fine. i can hear data centered on 433.900 via a icom ic-q7a. rx appears doa though. =/ bummer!

DanElectricalEngineer

| Jul 16, 2010 at 2:14pm

Hey folks. You'll notice in the (particularly poor) datasheet that the logic output high and logic output low values are specified with an output current of 10uA. If you are using a 5v supply (which the part requires) then the input impedance to whatever chip you're trying to read the data from (an MCU or Max232 chip or whatever) needs to be about 500kOhms or more to stay at or under the 10uA specified.

I've notice that as the output current from the data pin increases, the bit error rate increases. For those of you having problems achieving more than 2400baud, check the input impedance to your microcontroller pin. If it's much below 500K© then maybe use a buffer circuit to prevent the output from getting too loaded down.

I have successfully used this module to receive 4800baud NMEA strings from a GPS.

Good luck.
Dan