Help identify a 433MHz sensor/transmitter IC

[Mark Atherton]

Hello all,

I am interested in understanding more about a low cost temperature/humidity sensor transmitter operating on 433.92MHz.

Just received a temperature/humidity display unit from Ali express “Geevon Indoor Outdoor Thermometer Wireless With 3 Remote Sensors, Digital Hygrometer Indoor Thermometer With 200FT/60M Range”

Within one of the remote transmitters, the main processor appears to be a die covered in a blob of epoxy. The block is attached to a traditional thermistor, and humidity sensor as well as a small helical antenna for 433MHz. Processor directly controls a small LCD, has a push button input to toggle between fahrenheit and centigrade, and is powered by two AAA cells.

Using RTL_433, data format is identified as being used by FreeTec (Pearl) NX-3980 devices among many others (from nexus.c).

Can anyone identify the actual IC (die ?) being used for this application, and point to an associated datasheet ?

If this is the wrong forum to ask such a question, a pointer to a more appropriate forum appreciated.

Thanks, Mark

[Benjamin Larsson]

On 24/08/2023 22:30, Mark Atherton wrote:
> Hello all,
>

[...]

>
> Can anyone identify the actual IC (die ?) being used for this
> application, and point to an associated datasheet ?
>
> If this is the wrong forum to ask such a question, a pointer to a more
> appropriate forum appreciated.
>
> Thanks, Mark

Hi, most likely a custom IC or 1 time programmable uC. I have never seen
a datasheet for one of the simpler devices. Best advice I can offer is
to dissolve the epoxy and hope for some markings on the chip.

MvH
Benjamin Larsson