Edit: This design has issues. Do not built it until some things are corrected.
I am playing a bit with a deep sleep, battery powered ESP8266 (based on the Wemos D1 Mini, because I don’t want to deal with USB-to-Serial, mainly). After some tests, I get about 180µA in deep sleep with a HT7333, which is totally fine for me. I plan to run this on a 18650, which gives my about a year life.
Attached is a 5x5cm² board which integrates (all under the Wemos D1 Mini) the circuit for the LDO plus
- a TC4056A LiPo charging board
- a header to send a reset pulse for waking up the ESP when shorted - I am going to use this with a reed switch
- a capacitor as a 1bit storage (for simple state storage in combination with the switch in 2.)
- a high resistance voltage divider for reading the battery voltage
- prototyping holes around to fill up the 5x5cm²
I would be happy for improvements and suggestions before I send this to manufacturing. Especially, I haven’t tested the reset pulse yet, but since this is the way Arduino Uno & Co.work, it should be ok.
EDIT: Old versions of project deleted here and in the following. Refer to later postings for KiCAD project.
libraries.zip (14.2 KB)