Espruino JavaScript
Workable rf rx tx 433mhz module #665
Replies: 11 comments
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Posted at 2014-12-15 by DrAzzy This is something I'm interested in to0. I haven't been able to get the simple On/Off Keying modules to work reliably. They're close, but just kinda flaky, so you can't count on any one message actually arriving, and of course, line of sight only. I wonder if we could amplify them and bump up the transmit power a bit? :-P I think a different technology is needed if you require reliable communication at reasonable distances - like the NRF24, RFM69, etc - see the other thread for a bit of discussion. Right now, a lot of us are struggling with the issue of reliable wireless, so I really hope you'll dig in and make some progress - if enough of us monkeys with soldering irons stay on it, someone's bound to hit on something that works. I've got some RFM69's coming to try to see if I can get those to perform acceptably, though they're a lot more complexity than i'd like. However.... for anything better than those utter garbage cheap transmitters, it's almost certainly going to need SPI, or at least serial. |
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Posted at 2014-12-15 by Espruino_user_dk Thanks DrAzzy If required I am willing to use SPI or serial it is just adding more complexity and I am not sure how to proceed 😞 as I will have many RF devices each requiring their specific protocol |
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Posted at 2014-12-15 by DrAzzy Can you describe in more detail what you're doing? What devices, how many Espruinos etc? |
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Posted at 2014-12-16 by ChrisZ Have you seen the "radiohead" library by Mike McCauley at |
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Posted at 2014-12-16 by @gfwilliams @user6546 yes, I had come across that. It's quite possible that it could be tweaked to work with Espruino - although at the moment it'd have to be compiled in. A pure JS solution would be easier for people to work with. @drazzy the standalone RF module I have (normal eBay one, with an added aerial) seems to get relatively good range - near 50m through walls. I don't think you're ever going to get faultless one-way communications on 433Mhz though - I don't think even commercial systems manage it. The 433Mhz receive on Espruino is still a pain I know. Until I add native code (and/or debounce) on IRQs I don't think that'll ever be perfect. In terms of remote sensing, using some other device (like a PC) for the receive seems to work really well. If you get the remote sensor to send data at random intervals you might miss a few, but you'd still have a very reliable system. |
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Posted at 2014-12-17 by Espruino_user_dk For instance I have (pir) sensors from an alarm system I bought long ago but never used. With espruino I can analyse the rf pattern and use that specific protocol which I can already. There might be other rf devices with other protocols but it is possible to decode these too. So I have too be able to adapt to different protocols according to external devices.. this is why SPI, serial and others might not suit that well but I might be wrong (I hope) |
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Posted at 2014-12-18 by @gfwilliams Ahh - well, there have been some threads on getting 433Mhz receive with different protocols working. Basically right now you've got to write code quite carefully so that Espruino can decode signals on 433Mhz. Decoding the actual signal isn't a problem, but there's no much noise that it generally swamps Espruino. That means that trying to decode many different protocols using Espruino is going to be very hard right now. I've actually made some code that you can run on a webpage on your PC that will decode 433Mhz signals, and you could then add decoders to that for your other devices. For now it seems like the best compromise. With a very small amount of work it could also run under node.js or even on a raspberry pi. |
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Posted at 2014-12-18 by Espruino_user_dk Ok thanks Gordon. .. you mention a standalone rf module with a 50 meter range you use, Do you have a link for that to eBay? |
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Posted at 2014-12-19 by @gfwilliams The ones I have look just like this. They're one ones shown on the 433Mhz page. With an 18cm aerial and running off 5v, one in the loft seems to pick up everything pretty easily. You get a lot of noise though (I guess from other transmitters), so for starters I'd try the PC webpage thing as that has a bit more processing power available to it! I also noticed these superheterodyne 433Mhz modules which seem to advertise better sensitivity (-105 dBm vs -100 dBm), so they may be better? The lack of a trimming pot makes me feel better about them anyway! By the way, I recently added (it'll be in 1v72) the ability to call native code functions straight from the interrupt. With a bit of messing around with assembler you could write your own radio decoder for Espruino that'd be fast enough to handle whatever was thrown at it. At some point I'll come up with a simple toolchain for compiling C code into assembler that Espruino can use, and at that point it should get a lot more useful. |
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Posted at 2014-12-21 by Espruino_user_dk Ok exactly the same as mine it appears so it is strange it is not working for me... when you say... one in the loft, what do you mean? I ordered the superheterodyne and will give it a try... Thanks |
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Posted at 2014-12-21 by @gfwilliams I mean I have one in the roof of my house, connected to a PC up there. It seems to pick up most signals for devices quite well. |
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Posted at 2014-12-15 by Espruino_user_dk
Hi all
Can someone provide a link to a rf 433mhz module (rx & tx) , no SPI, just a simple module that works and actually gives a range of 30 metres as often promised. I am kind of stuck at the moment, nothing really succeds and it is essential to be able to communicate across components if wanting to make any use of espruino and devices.
Any help much appreciated :)
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