Ultra Low Power thermometer

With a current consumption of only few uA, this thermometer is capable of running for years from single CR2032 (and forever from solar cell)

Miroslav Hancar

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Description

-Ultra low power thermometer with an average current consumption of only ~3uA
-PIC16LF19175 & MCP9700A & MCP1501(-10 or -20)
-1 measurement per second
-Range: -40 - 52°C (with 1,024V reference) or -40 - 125°C (with 2,048V reference)
-Can be powered by a CR2032 or experimental "solar 2032" - 10 BPW34 connected in series without DC-DC converter
-MCU is in sleep mode for most of the time

Details

Files

lowtemp32.X.zip Source code x-zip-compressed - 2.01 MB - 10/15/2022 at 18:27		Download
lowtemp32-LUT.production.hex hex - 16.57 kB - 06/14/2020 at 11:51		Download
solar_pcb.sch sch - 221.61 kB - 06/14/2020 at 11:12		Download
solar_pcb.brd brd - 67.49 kB - 06/14/2020 at 11:12		Download
lowtemp32.sch sch - 708.10 kB - 06/14/2020 at 11:11		Download

View all 6 files

Components

1 × PIC16LF19175
1 × MCP1501
1 × MCP9700 Sensors / Temperature, Thermal
1 × DE123-RS-20/6.35 Display
10 × BPW34

Discussions

Serhii Trush wrote 06/04/2026 at 13:00

Hi. Thanks for the article.

The BPW34 batteries are very delicate, in my watch(the project is available on my profile), they were already failing when I had it sealed, and then I had to replace a few more of them six months to a year later.

Are you sure? yes | no

Peter Loës wrote 05/13/2022 at 06:40

Dear Miro, I had a idea about multiple layers of solar cells(cr2032)with transparent thin layers.

1. Layer output 100% 3,20V
2. Layer output 15% 0,48V
3. Layer output 5% 0,16V = 3,84V good enough for electronics with memory cards.

Are you sure? yes | no

Peter Loës wrote 09/16/2021 at 07:10

"Solar 2032" is definitive the next step!

Pherhaps you can compare Coincell CR-2032 3V@225mAh via Solar2032 ?V@?mA

and show more measurements about little light.(Inner rooms and outdoors)

Are you sure? yes | no

Erin RobotZwrrl wrote 06/24/2020 at 16:16

The solar coin cell board is awesome! Nice find on the BPW34s! Very creative, way to go. It has inspired new ideas for some projects!

Are you sure? yes | no

Mike Szczys wrote 06/22/2020 at 19:37

That coin cell holder form-factor for the solar cell board is brilliant!

Are you sure? yes | no

Miroslav Hancar wrote 06/22/2020 at 20:32

Thank you!

Are you sure? yes | no

Gabriel wrote 06/14/2020 at 12:41

oh, and that solar CR2032 is Awesome!

Are you sure? yes | no

Gabriel wrote 06/14/2020 at 12:40

Great execution! Kudos on using PIC, its nice to see other PIC people on here. Maybe its a coincidence in this case, but i too tend to try and build al my projects using all Microchip Parts.

Are you sure? yes | no

Miroslav Hancar wrote 06/14/2020 at 15:08

Thanks! I use PICs and MCP parts in almost all of my projects.

Are you sure? yes | no

Similar Projects

Run a low-power MCU efficiently from an AA(A) or button cell

Ultra Low Power thermometer

Description

Details

Files

lowtemp32.X.zip

lowtemp32-LUT.production.hex

solar_pcb.sch

solar_pcb.brd

lowtemp32.sch

Components

Discussions

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Ultra Low Power thermometer

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Just one more thing

Description

Details

Files

lowtemp32.X.zip

lowtemp32-LUT.production.hex

solar_pcb.sch

solar_pcb.brd

lowtemp32.sch

Components

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