Wireless Thermometer with using only a HC-12

simple solution which doesn't require any additional hardware

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I am continuing my theme of using the HC-12 module in a non standard manner.
I wanted to make something with using only a HC-12 module.
And I did it... as I could :)

Let me show you another cool thing with using the HC-12 module.
In this case it will be a wireless thermometer with using only a HC-12 module as a sensor and as a transmitter simultaneously.
With a new custom firmware it will transmit a data from a temperature sensor which is embedded in the Si4463 chip.  This solution does not require any additional hardware but a HC-12 module.

The transmitted data can have been received with another HC-12 module that have a default firmware and must has been set to default channel. It can has been done with the AT command 'AT+DEFAULT' when the SET pin is connected to the ground pin. 

A measuring step is 0.2 celsius degrees.

The received data looks like "+12.3~C" or "-12.3~C" in a window of a Terminal programm.

How it looks like can be seen on YouTube:  

hex - 11.19 kB - 01/28/2018 at 19:18


  • Be careful

    vladlen11/29/2018 at 10:30 0 comments

    Note that you frequently might meet a trouble with tuning it because the crystals on different samples are different from each other if they were bought from the different sellers!

    It was discussed earlier. link

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  • 1
    Step 1

    Just load new firmware to one HC-12 module and receive the temperature with using another module which have a default firmware.

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ke6zfi wrote 12/14/2018 at 06:17 point

Great project, any chance of sharing the source code for others to build upon?

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karczewski.szymon wrote 02/21/2018 at 12:32 point

Hi, I've just bought HC-12 modules and I'm looking forward to try your firmware, but I also wonder if you have written everything from scratch or used some *base* code available somewhere? I want to keep this module as low power as possible by transmitting data only above certain temperature and in greater time intervals.

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vladlen wrote 03/01/2018 at 11:28 point

I have used the SPL from ST. Also I have used fragments of someone else's code that I found on the Internet to write a little and simple library that drives the Si4463.
For myself I wrote another firmware that transmits a paket only one time in about 1.5 minute. With this FW the HC-12 module consumps about 0.1mA between transmitions.

I can try to help if you need .

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brian wrote 02/01/2018 at 02:22 point

This sounds great. I'll give it a try. Thx!!

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vladlen wrote 02/01/2018 at 05:40 point

Thank you too!  

Awaiting your comments about its working.

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