I thought I’d write up my findings when using the TP4056 Li-Ion charging boards as a lot of people seem to be interested in them lately for charging circuits containing ESP8266 wifi chips which are rated from about 3.3-3.6v. Ideally a Li-Ion, LiPo or LiFePo4 battery. Note that the TP4056 can’t be used to charge LiFePo4 batteries (or NiMH, Alkaline etc). First up, a couple of links to Julian Ilett’s videos of the older unprotected USB-mini board and another video comparing the newer protected USB-micro board which some people refer to as MP1405.

I’ve ordered a few gadgets to play with: PL2303HX USB UART cable 2x Samsung ICR18650-26F Li-Ion batteries 2x GTL Li-Ion batteries Quad MAX7219 8×8 LED matrix 5x USB 18650 protected chargers 300x 0603 resistors (100 each of 1k2/2k2/2k) Round 18650 USB power bank Square 18650 USB power bank LED tap filter Raspberry Pi camera mount Mobile phone wide angle macro lens Mobile phone fisheye/wide/macro lenses Mobile phone microscopic lens Micro USB hub/ethernet dongle 3x RPi3 heatsinks I plan to make another LED matrix clock and either use my Raspberry Pi camera or Android phone as an inspection camera for soldering.

I’ve finally got around to adding British Summer Time detection to my LED matrix clock, I’ve also reduced flash wear and connection time by using the new persistent() method from the WiFi library. I’m still saving the UTC time to the RTC module, just displaying +/- the hour. The LiFePO4 battery is still putting out over 3.1v after 2 months. The final code is below: #include <ESP8266WiFi.h> #include <WiFiUdp.h> #include "LedControl.

I had a cunning plan to use the bottom half of my WIFI Witty board as a programmer for bare ESP-12F boards with those white breakouts, but then found that they rely on the regulator being on the ESP12, the whole of the Witty is 5v. So I figured out that the solder pads on the underside of the breakouts are for a SOT-89 regulator, albeit with a stupid GND-VIN-VOUT pinout, so an LM1117T or suchlike wouldn’t do:

I’ve been working some more on my 8×8 LED matrix clock. I’ve added a DS1307 RTC chip, which has to run from the 5v pin on the NodeMCU and use 10k pullup resistors between 3.3v and the SCL/SDA pins on the NodeMCU and DS1307. I’m using the Adafruit fork of RTCLib as it has better ESP8266 support and uses unixtime. I’m using this chip as I’ve got a load of them and already have a veroboard setup with the coincell and crystal.