I am having problems getting the popular Tx and Rx modules to work. My receiver shows a square wave output all the time and is not responding to Tx commands.
I have now bought three sets thinking I have damaged them. I have checked my wiring many times and tried a breadboard hook up without any microprocessor and the output is the same on all modules. If I take the transmitter out the circuit , the output of the RX is the same.
Has anyone else had this problem and could it be interference from WiFi etc.
PS I am a newbie
Start here
Posting a schematic, not a frizzy picture showing all connections. Also post links to each of the hardware devices, be sure they give technical details. If you can also include a picture of your setup.
That's normal.
The data slicer of of a 433Mhz OOK receiver outputs digital noise, until data is received.
Leo..
Thanks Leo. My understanding after looking at dozens of articles is that the receiver gives a high with signal and a low with no signal. I have seen videos of the units being used without an mpu asa wireless door bells etc. My output is a square wave from high to low with no tx connected. I accept that the problem is of my making but I don’t know how to get round it
We have no idea which modules you are using - but the most common TX/RX modules do not behave like you are stating as Wawa pointed out. You need to give details of the modules at the very least.
There are receivers with built-in decoders that can give a high or low on four (or eight) outputs.
Google "HIB03" for an example.
Basic receivers don't have these, and you must use your own decoder (Arduino).
Those output random noise until they receive something.
As MarkT said, post a link to the modules you have.
Leo..
The identification on the re module is MX-RM-5V also 080408. They look the same as all the others I have seen on arduino projects and the data pin on the tx is ATAD ie the wrong way round. My last experiment only had v+ and 0v applied to the Rx module with an oscilloscope on the o/p. Thanks for helping
Standard module, outputs random noise when no signal is received.
I was under the impression that ASK consisted of packets of transmission and no transmission so during no transmission does the output behave randomly? If so how can the received data be relied upon. I think I need to look at an alternative technology. Thanks to everyone who tried to help
There is no problem with data reliability, although the module you have (with the coil) is the cheap/nasty one that has an unpredictable range.
Leo..
Radio is inherently unreliable. Once the receiver picks up a valid signal, the output of the receiver will follow the transmitter, up to a point. Beyond that, message transmission has to include a means of error checking, which is implemented in Arduino libraries like VirtualWire and Radiohead.
I recommend to start with VirtualWire and the simple examples in that library. There are plenty of tutorials on line.
I was hoping not to have an mpu at the receiver as per several examples I have seen on YouTube. I designed a transitor time constant circuit to switch a relay. But as I stated the output is switching as a square wave on all 3 modules. I know it my fault but trying to figure it out is problematic. I am now looking at spare fob and relay set up by connecting tx button to the mpu. Seems ok at the moment.
If you want stand-alone, then buy a fob with encoder (most keyfobs do have that extra chip) and receiver with decoder (not just a receiver). An Arduino can mimic a keyfob with encoder, as can an Arduino act as decoder chip.
Leo..
I am now using a proprietary fob and relay. Using it a 5 volts gives plenty of range and I can control using I/o of arduino nano. Thanks for your input. I hope to return to the 433 mhz devices in the future to solve my problem
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