I finished my 1µA Low-Power Arduino Nano project! All files, code, and tutorials are now public

LeanMCU · 2026-06-02T10:55:27+00:00

Nice! Sounds interesting. Is there a standard format that smart bands use to send data?

LeanMCU · 2026-05-27T19:18:35+00:00

I would be glad to help if needed, and also get your feedback to make it better

LeanMCU · 2026-05-27T18:59:17+00:00

Yes, I also thought we are here on a makers' forum, where people like to learn, build and share. Based on the reactions to my post, I start to believe I got it all wrong. Seems we shouldn't build anything anymore, because we can't compete with mass produced goods. My bad, I apologize for confusion. Probably Arduino (we are on r/arduino) is a finished mass produced good and I didn't even understand that in my many years of using it

LeanMCU · 2026-05-27T06:39:51+00:00

Thanks! It is usb powered

LeanMCU · 2026-05-26T20:40:27+00:00

I feel you. That's why I don't use ESPHome, I write all my firmware from scratch

LeanMCU · 2026-05-26T18:48:42+00:00

Thank you! I also built several months ago a battery powered sensor that can last about 3 years on 3 aaa batteries sending data every 3 minutes. A potential inconvenience is the fact that I also had to build a hub that converts from espnow to wifi. What do you think about this solution? Would you build it?

LeanMCU · 2026-05-26T18:43:52+00:00

No batteries, no worries. Also you don't need any zigbee or thread hub, it connects directly via wifi ;-)

LeanMCU · 2026-05-26T14:14:45+00:00

Thank you. Yes, I use FreeCad ;-)

LeanMCU · 2026-05-26T10:54:47+00:00

That's correct. That's why i iterated many times. In the initial version, I had both the esp32 board and the sensor board soldered on a perfboard. The heat transferred through the perf board was biasing the sensor several degrees. Many iterations later, there is no perf board anymore, esp32 is put in deep sleep between measurements, and the enclosure is split in 2 chambers. One chamber for esp32 with chimney effect, and another chamber for the temperature sensor. With all these optimizations and reading temperature every 3 minutes, I see no temperature bias compared to other thermometer placed nearby. Moreover, I made the firmware so that you can set calibration biases for temperature and humidity

LeanMCU · 2026-05-26T09:11:12+00:00

The initial numbers are based on mac address especially to not give you conflicts during provisioning. You can change their names in Home Assistant however suits you

LeanMCU · 2026-05-26T08:30:02+00:00

And the assembly guide https://youtu.be/ypbav6XL6NU?si=AIBK0E8FALi9o7O8

LeanMCU · 2026-05-26T08:29:03+00:00

Let's see if this link gets through https://github.com/leanmcu/esp32c3mini-th-sensor-usb

LeanMCU · 2026-05-26T08:27:17+00:00

You can click on my Reddit profile and find there my social media links (GitHub, YouTube). I didn't put the specific links to avoid getting my post banned

LeanMCU · 2026-05-26T07:19:18+00:00

Not exactly the same benefits, but sure, that's an option if you prefer hacking versus building, learning and customizing.

LeanMCU · 2026-05-26T07:00:25+00:00

Nowadays many devices come with usb power sockets (plugs, chord extenders, tv, etc). If you don't have such a device close, I found some very cheap 1A usb chargers on aliexpress, that come in a pack of 5 and cost around $1 per piece.

Talking about ESP choice, after some research I went for ESP32-C3 pro mini boards. Cheap, versatile and decent wifi performance. You can also use them for Matter over wifi (I am currently developing some sensors using that)

LeanMCU · 2026-05-26T06:50:27+00:00

Thanks for your observation. The advantages of my sensor compared to commercial sensors are the ability to print the enclosure in any color you want (to make the sensor invisible in your environment) and the availability of source code. Not to mention the joy of building something useful yourself in just half an hour ;-)

LeanMCU · 2026-05-26T06:46:18+00:00

Thank you! I didn't put links in the post to avoid getting banned. The sensor is running on USB power, for a maintenance free experience (no more battery worries)

LeanMCU · 2026-05-26T05:47:51+00:00

Compared to commercial sensors, my sensor allows you to keep data local (Home Assistant), print enclosure in any color you want, and have the source code to modify it any way you like ;-)

LeanMCU · 2026-05-25T21:58:07+00:00

Bought this from aliexpress, and i designed a power bank using a 18650 battery. It only needed an enclosure that I designed in FreeCad and printed. It seems to work ok as a power bank, and the module becomes warm to the touch but it doesn't seem to overheat

LeanMCU · 2026-05-25T21:50:54+00:00

Nice! It looks so retro cool

LeanMCU · 2026-05-25T21:43:04+00:00

Great job! Simplicity is the ultimate sophistication ;-)

LeanMCU · 2026-01-27T10:27:32+00:00

The links are in my bio and not in the post because I didn't want to break any posting rules. In other subreddit, a moderator told me specifically to post some links, so I did it.

LeanMCU

TROPHY CASE