January 6, 2026

Bluetooth - my ThermoPro gadgets

My adventures with Bluetooth began with the purchase of a couple of bluetooth temperature gadgets made by ThermoPro: The TP357 has a display, uses a single rechargeable AAA battery, and claims a 260 foot range.
The TP351 has no display, also uses a pair of nimh AAA rechargeables, and claims a 260 foot range.
There is also a TP358 which has bluetooth and also displays time.

Neither is waterproof or rated for outdoor use. Both expect you to use their free phone app.

The ThermoPro TP351

This comes with a pair of alkaline AAA batteries. I put them in and watch the logs on my linux machine with my TP-link USB500 in place and see nothing. The TP351 has no display, no switches, no lights. It is just a white box with a nice lanyard. So let's try installing the phone app.

I grab my Pixel 6 android phone, do a search on "thermopro sensor app" in the play store and install the app. I launch the app. I say yes to the first Android permission screen to allow it to look for devices, but say no to notifications. I now click the "add device" button. It sees a TP351S. There is a red + button next to that, I touch it and it all works.

It shows me 80.8 in my lab. I have two other sensors -- one shows 80, the other shows 82, so the 80.8 is at least reasonable. It seems to show me battery status too, which is nice. I walk outside with my phone, which puts two walls between me and the sensor, click the update button and it seems to work fine.

Does this have any advantage over the TP357? The TP357 uses only one battery and has a display, and it is cheaper (at least with discounts currently being offered). Did I make a $13 mistake buying an older unit.

Aha! Here is one thing -- the TP351 will store 2 years of data, while the TP357 only claims to store 1 year.

The ThermoPro TP357

This uses a single AAA battery, has a display, is smaller and cheaper.

Linux and the Thermopro devices

The question is, how hard will it be to get some linux code talking to one or both of these Thermopro devices? It turns out that I had it working in under and hour. Home assistant is an open source project that includes support for a variety of ThermoPro devices.

Here is the play by play as I try to repeat what the first link describes.

Have any comments? Questions? Drop me a line!

Tom's Software pages / tom@mmto.org