JFET

Three-color ink screen calendar

Overview

This project is the second modification of @duck ’s board. The original open source address is: 4.2-inch ink screen calendar

The cable holder was changed to a three-color screen center-mounted cable design, and the space was compressed as much as possible, and the density of components was increased, resulting in an extremely large battery volume.

Update log:

2021.9.22

Added side cable arrangement version (interest-related)
Fixed some bugs (forgot what they were)
Automatic download changed to dual nmos, too lazy to find materials

2021.3.27

Continue to optimize the schematic diagram to make it clearer and easier to understand and standardize.
Solved the problem that the esp8266 cannot start without forcing the TX pin of the esp8266 to be pulled up (if it still doesn't work, please solder a 10k resistor at the NC resistor )
Change the ch340c to a 3.3v level power supply to unify the power supply and level.
Solved the problem of low battery power displayed on the screen after startup without connecting the battery or turning on the power switch.
Continuously optimize wiring

2021.1.26

Reconstruct some schematics to make them more standardized and easier to read.
Replace the LDO with HT7833, which theoretically eliminates the need for tantalum capacitors.
The charging chip is replaced with the stronger TP4056, which theoretically increases the charging power by 300% compared to the original version.
An automatic charging switching circuit has been added, so there is no need to add a battery during debugging.
The temperature and humidity sensor was replaced with the SHT30, which is cheaper and more accurate.
Added ESD diodes to avoid unnecessary losses caused by static electricity on dry hands in winter
Starting from this version, the charging interface will be replaced by the extremely advanced Type-C and will no longer support the backward MicroUSB.

If you are interested, you can join the QQ group 556951885. There are entry barriers to the group. You must either provide photos of Lichuang's board or answer the questions correctly to join the group. I can't do either of these, so sorry. Support and firmware are provided free of charge for personal production. If you want to use it commercially, please leave.

Design Files

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