433.92Mhz Transmitter problems - no signals detected

Hi

I have been trying to do this http://www.espruino.com/Remote+Control+S­ockets , as to the receiver part for detecting the signals sent from the remote control - I have been using the suggested code. I get no response at all and can not see any bit patterns - why is that? The receiver I use is this http://www.ebay.com/itm/433Mhz-RF-transm­itter-and-receiver-link-kit-for-Arduino-­ARM-MCU-WL-GOOD-QUALITY-/121131013642?pt­=LH_DefaultDomain_0&hash=item1c33f8960a and I did notice that the receiver has an Working voltage: 5.0VDC +0.5V so hopefully this is not the reason I can not make it work - what might be wrong?

Thanks...

Assuming you're using VBat while running off USB (not 3.3v), the receiver will work.

However:

The code given there works with a specific kind of socket only - it's expecting the protocol described in the page you linked, a 5 ms sync delay, and the specified lengths for ones and zeros. However, a remote control socket from another vendor could use a totally different protocol - different encoding of ones and zeros, different number of bits, shorter sync, etc - and the code would need to be modified appropriately. So unless you're using compatible sockets, that code won't work.

Receiving on the Espruino is kinda lousy right now - it will pretty much hang the Espruino (if it doesn't make the Espruino become almost unresponsive, I'd suspect bad wiring - when there's no signal, the receivers just spit out noise, and the Espruino gets bogged down trying to handle it).

Luckily, Gordon is planning several improvements to Espruino to address these issues, so this should get better in the future.

See other threads:

Gordon's thread talking about possible improvements:
http://forum.espruino.com/conversations/­257663/

Threads I started about this. First one has a lot of information on my making my own protocol, second one led to Issue #452 on github.
http://forum.espruino.com/conversations/­255528/
http://forum.espruino.com/conversations/­258248/newest/

Thanks again DrAzzy

Hmmm, tested it with vbat (bat) and it did not change a thing - I measured around 4.7-4.8 volt. I have tested with several receivers (to my surprise I bought 5 pieces instead of 1). Transmitter has a 12V and 23A battery so maybe signal is not weak but I have no means to measure this.

Thanks

Do you have a link to the transmitter you're using?

If the protocol is different then the receiver code may not be able to get any useful information for you... I don't suppose you have any kind of oscilloscope/logic analyser? You can output the raw data from the receiver, but chances are there will be so much noise that it'll be very hard to pick out the actual signal...

So if you try this code:

function sigOff(e) {
  console.log(e.time-e.lastTime);
}

setWatch(sigOff,A0,{repeat:true,edge:"fa­lling"});

It'll output the width of all the pulses received.

You'll probably get lots of lines of random numbers output (all the time), which at least shows the receiver is working.

When you hold down a button on the transmitter you may start to notice that the numbers all start to be mostly the same (maybe falling into 2 distinct ranges) - and that might help to give some idea of how to decode the data that is received...

Hope that helps!

Thanks Gordon - the actual problem was a solderless pin header that did not make a connection proberly - now soldered and giving bursts of data :)

Great! Thanks for letting me know :)

Ok, so got it working and now able to turn light on and off with espruino.

When doing the analysis with Espruino, to find the bit patterns, I did not notice any section that could be interpreted as the "training burst" - I know it does not work without it but I just do not see why I have to add it if the signals from the remote did not show it?

Thanks..

Did you get the 'training burst' from the discussion on the forum?

I think the remote controls don't use it because they just transmit the same data over and over. The very first transmission may not be received properly but it doesn't matter because there are many more.

If you're writing both TX and RX on the Espruino then it just makes life a lot easier. The long pulse at the front gives Espruino time to process what was in its input buffer (if there was a lot of noise before) and also lets it know that it's at the start of a transmission.

Yes, I got the 'training burst' from forum - I found out it was not needed anyway, so now removed. However, the transmitter I am refering to in comment 1 appears not to have a far range. Now that I have 2 socket running and working with Espruino (well almost) the distance between transmitter and sockets is now to far. I thought a distance of 30 meters were to be expected but just 3 meters seem to far away, could this really be? The remote is powered by a 12 volt battery so a great deal more than the 4.7 - 4.8 volt from Espruino, could this explain it?

Thanks

That does seem very strange - my transmitters seemed to work over a pretty long range (and they look identical). I'm not sure about the circuit on the transmitter but it could be that it actually needs 5v on the data pin in order to transmit properly.

To do that:

• Make sure you're using a pin from http://www.espruino.com/ReferenceESPRUIN­OBOARD that doesn't say 3.3v by it
  
• Connect a 1k resistor between that pin and the 5v line
  
• Use the command pinMode(YOUR_PIN, "opendrain") before you do anything
  
  

Now you'll get a full 5v swing on the output.

Other thing is some of the modules actually have a hole labelled 'ANT'. If you solder a piece of wire onto there it might really help (you'll have to google what the length should be for 433Mhz)

Hi Gordon

Actually, there is a hole labelled 'ANT' so I guess it is required then? I will try it out.

I have the wifi device cc3000 on the other BAT pin does that affect the transmitter on the other BAT pin somehow?

Thanks again :)

An update - the antenna made a difference and it now works. 17.3 cm wire is required if anyone is interested.

Thanks for your help.

Using an ANTenna makes quite a difference. Ideally, it should be the proper length for 433mhz, but there's some debate online as to what that length is. Theoretically, 17.2cm, but some people say they get better responses with a longer one. I just grabbed a piece of wire around a foot long and used that, and it made a big difference.

The performance still left much to be desired, though.

Now that I got the transmitter working - I now face problems with the receiver and this time I do not see an antenna hole. When using 5 V I get a lot of signals into the receiver but I am able to deciffer the signals that I want so I can see whenever I push the remote for the sockets or when my pir sensor (almost forgotten from our old alarm system) is activated - the on / off pattern is recognized - all fine, however, only when transmitters are close to receiver. Again I expected 30 metters to be the standard but having a distance of 3 meters is the limit.

Thanks...

You sure you don't have an antenna hole?

The most common of the cheapo receivers has an (unmarked) antenna hole in the corner opposite the opamp.

Ok so I found some images where I could see where to attach the antenna - but it did not change much. I have used the same length as for the transmitter.

Could it be that both the transmitter and receiver is close to each other (would like to have both tx and rx functionality on same Espruino board) and thereby generating noise of some sort? In the tests I have not used the transmitter at the same time as receiver however both is powered.

Could it be I need thicker wire as of now I just use the thin wires that came along with my breadboard.

Thanks...

Could anyone suggest an affordable rx and tx 433 mhz with a long range, maybe a transceiver- even though I am not entirely sure how to solder as they appear to have other pins.

Thanks

@Espruino_user_dk, I have no experience with these, but they are cheap enough to consider, and I am sure you can find others:
Link1,
Link2
My recent long range topic.

Let us know what you do :)

Just to add that the modules Manxome has suggested contain a radio and an encoder/decoder. You'd use them slightly differently, but once you have them working they'll probably be more reliable - however you won't be able to decode transmissions from things like electricity monitors, as they use their own protocol.

LOL, the more I learn, the more I realize how little I know :)

Ok so analyzing remote controls and then afterwards trying to imitate this is not possible?

Thanks

@Espruino_user_dk it is possible, but you have to use the right modules. If you use a module without a decoder then you can decode everything yourself (which is a bit more difficult), however if the module contains a decoder then it'll just ignore everything else.

Ok but it seems like a jungle... how to spot Lora modules without decoders? Does anyone have suggestions to modules?

Thanks

I would be glad if anyone had any experience they would share..

Thanks