HC-12 firmware compatability

[Les Jones]

I have been using HC-12 modules for about the last four years. they have been bought from various suppliers and have all worked without any problems. I recently bought another two and when I tried them they would not communicate with the existing modules. They would communicate with each other. My first thought was that they were not configured to the default settings. (B9600, RC001, RP +20 dbm, FU3) On checking the settings I found they were the default values. I then checked one of the original modules as I had never checked the settings of these. They too were set to the default settings. I did find out that the original module I checked was firmware version HC-12 V2.6. The recently bought modules were V2.4. (These were bought from ebay seller st-8078. Do any forum members know if there are know problems with different firmware versions not working together ?

Les.

 

[Nigel Goodwin]

There's a story about it here:

hc-12 – Hackaday

hackaday.com

 

[Les Jones]

Hi Nigel,
Thank you very much for that link. I am fairly sure the crystal frequency is high by about 3 Khz. I used a communications receiver (Kenwood R1000) in CW mode to compare the frequencies. I tried touching the scope probe on the crystal connections but that changed the hetrodyne frequency by several hundred hz so that ruled out directly measuring the frequency with a frequency counter. As the multiplication is about 15 that would make the new modules about 45 Khz high of the channel. I have now ordered some HC-12s from a supplier that I used last year who supplied modules that were compatible with all the module that I already had.

Les.