This project is the version 2.0 of a previous project. The main goal was to have something relatively small and compact.
The main controller is an Atmega328 from an Arduino Pro Mini running at 3.3V and 8Mhz.
The system is powered by a LiPo battery that can be reloaded with a small micro usb board from eBay (based on the TP4056).
There is a load sharing circuit which balances the power when the micro USB is plugged in.
The power supply is built with a MCP1253 which provides steady 3.3V to the circuit.
Notifications (micro SD card checking, signal searching, data recording,...) are displayed with 4 LEDS based on the WS2811 controller (neopixel)
The board has one push button that can be used for different actions (depending on how long you press it).
I just created the project ! I made some test, everything works well ! I am waiting for the WS2812 leds to arrive (they are missing on the project pictures) and I will probably post a video to show how it looks like .
To come : Schematic, PCB, Code and Docs to come on github soon.
I have a few questions refering to the load sharing circuit which balances the power. The first, if this circuit switches load from BATT to IN+ when the charger is working, and if the MOSFET affect to the TP4056 charge procedure. The second, is if i can use a LDO regulator instead a MCP1253 Positive-Regulated Charge Pump. A brief summary of the circuit operation will be appreciate. Thank you very much ;)
Sorry for the delay, I was quite busy. Regarding the load sharing circuit, I got some inspiration from here : http://blog.zakkemble.co.uk/a-lithium-battery-charger-with-load-sharing/ When the charger is working, IN+ is 5V so the circuit uses the usb power. The problem with regulators is the dropout voltage. This charger is for one cell only meaning 4.2V at best and down to ~3.3V. unless you can get a really low dropout regulator or your circuit requires less than 3.3V, I don't think it is a good idea.
Hi,
Thanks for your comment, I didn't know something like that existed :)
Oh well, at least mine has a built in battery charger and comes in a nice enclosure :D