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Forum Index : Microcontroller and PC projects : HC-12 failure.
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| Phil23 Guru  Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
Anyone seen any failures in these modules? Checked my controller earlier & it had lost all coms at about 7:00am. System consists of a Master CGM2 that sends requests every 2 seconds; [Code]SendHpData SendScData SendChData & repeat above...[/code] Each of the others responds with a data block & checksum. Wiggled everything everywhere & swapped a few.... then eventually plugged a USB HC-12 dongle into the laptop. It was only occasionally seeing the above request, at a 2m range. Moved the USB module besides the master & it received all the outgoing strings. Swapped that one out & back to normal. Seems that one now has a very low transmit power. Haven't checked for corrupt config yet, they are all at default, but just wondering if others have seen any % failures. They've been in service for over 18 months. Cheers Phil |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9749 |
Well, I can tell you I have to-date used about 200 HC12's in various things, and I have not had one single failure - yet. They seem very bulletproof and tend to need a lot of killing. I am hopeful that you just struck a dud one. Some checks would be worthwhile though - supply voltage etc. Smoke makes things work. When the smoke gets out, it stops! |
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| Alastair Senior Member  Joined: 03/04/2017 Location: AustraliaPosts: 161 |
Phil, When I recently started using HC-12s I was very pleased about how easy it was to get them going. After I rebuilt my breadboard prototype into a box I found that whilst it would work when nearby, it would not work at the distance required like it had before. Assuming I had got something wrong I checked everything. In the end because I could not think of anything else to do, I did a factory reset. After that it all started to work again. I know not why. I do switch channels for each data source and I can only assume a glitch occurred which confused it. Cheers, Alastair |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2462 |
assuming configuration data is held in flash (a fair assumption) there will likely be a limited number of times it can be changed. although this may be up in the 10's of thousands of times, a channel change every few minutes will kill the flash area used in a matter of months. 12 writes/hour * 24 hours * 35 days = 10,000 writes. cheers, rob :-) |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
RE: channel-switching... interesting - I hadn't really thought of it like that... so probably best choose a config and stick with it. I adopted an address-based star network as a foundation for a number of systems based on wireless comm's all on the same channel. I did play with channel switching but as it made broadcasting next-to impossible I ended up doing the right thing for the wrong reason  this might help (?) |
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| Alastair Senior Member Joined: 03/04/2017 Location: AustraliaPosts: 161 |
Rob, I did not think of it that way also, but unlike the Captain I made the wrong decision and regularly switch channels. Clearly you are right because if you change the channel, power down and then up again, the channel remains the same. I need to do a bit of s/w changing and use a broadcast approach with polling to alert a node. I hope I am not too late for the HC-12s. Cheers, Alastair |
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| Alastair Senior Member Joined: 03/04/2017 Location: AustraliaPosts: 161 |
@Rob, After your warning re the channel changing I have checked the code on the 2 nodes and the base. Pleased to see I did no mode changing on the nodes so they are ok. I did do channel changing on the base, but since one node is being updated not much would have happened. I have now changed to a method inspired by CaptainBoing's approach. I have the nodes listening and the base prefaces all requests with N1 or N2 depending on which node is to respond. Seems to work ok. I did plan to add an identifier to the responses from the nodes but it doesn't seem necessary as the nodes only send info on request. Ooops just realised that is not true - the nodes send an INIT request on startup to get the date & time. will have to add the identifier. Grrr. Cheers, Alastair |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
No Channel switching in my case. Do wonder though about the mention of lowering supply voltage in the documentation.  Phil |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2462 |
i've only ever powered them from 3xAA cells = 4.5 volts. an LDO can then nicely brings this down to 3v3 for a micromite. bear in mind that the HC-12, when operating on the 'legal' channels (1 to 4) is making use of a shared set of frequencies intended for remote control applications. as such you should not be transmitting continously, but just sending short bursts of data with reasonably long gaps (of a few seconds at least) in between. any continuous transmission may, for instance, block nearby wireless garage door openers from functioning correctly. one should always try to be considerate of other radio spectrum users when designing with an HC-12 or similar 433MHz devices. cheers, rob :-) |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
Glad my memory has been jolted... My 2 second polling interval, but intention is too frequent; 10 Seconds is the commented out value I intended to use, but lowered it to 2 secs for testing & debugging. And yes, I do notice it's impact, my electric gate takes a few more presses of the remote to ensure it open when I get to it  , and the 433 Energy monitor updates less that every 30 seconds,Phil |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
On a side note & I've mentioned this in an earlier post, for those who don't have an (Expensive) RF Spectrum Analyser, (Like me), a USB TV dongle is worth investing in as a Spectrum Analyser. Even better is the SDR (Software Defined Radio) kit reviewed in this months Silicon Chip.  It's $30.00 on Bangood. With my SDR dongle here I can see all of my 5 other 433MHz devices, along with the HC-12's. Well worth the $10.00 a USB dongle only, but the $30.00 kit offers a few small advantages. Cheers Phil |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9749 |
[Quote=Rob]bear in mind that the HC-12, when operating on the 'legal' channels (1 to 4) is making use of a shared set of frequencies intended for remote control applications. as such you should not be transmitting continously, but just sending short bursts of data with reasonably long gaps (of a few seconds at least) in between. any continuous transmission may, for instance, block nearby wireless garage door openers from functioning correctly. one should always try to be considerate of other radio spectrum users when designing with an HC-12 or similar 433MHz devices.[/Quote] COMPLETELY agree with that. Generally speaking, a duty-cycle of 10% is what you should aim for. IE: 90% of the time, the module is NOT transmitting. IF you are hogging the band, and people complain to the radio inspector that their remotes aren't working, and they find out it is you doing it, you can be fined. This despite the 433MHz band being free to use for just about anything, but it is free on a shared basis. If you want to run 90% duty-cycle, you need a license.   Smoke makes things work. When the smoke gets out, it stops! |
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