4.2-inch ink screen weather forecast clock based on ESP32 C3

Compared with the previous ESP8266 version , this version replaces the SoC with the latest ESP32-C3. Compared with the previous one, it has stronger performance, more Bluetooth functions, more IO, and lower power consumption.

Update log:

2021.09.23

1. Remove CH340C and use esp32 built-in USB PHY for downloading and debugging
2. Optimize routing
3. Bantang wants to drink Coke today

Compared with the previous version, the following new features have been added:

1. The main SoC is replaced by ESP32-C3. Later versions will add Bluetooth distribution function, and the power consumption will be further reduced compared to the ESP8266 version;
2. An independent RTC chip is added, which can realize offline clock function and greatly optimize the accuracy of time;
3. Supports resistor + transistor and dual nmos download methods. It is recommended to use dual nmos, which has fewer peripherals and can also significantly reduce leakage current, thereby reducing power consumption;
4. CH340C uses 3.3V power supply, which makes the entire system level unified, and has added the power of disconnecting USB to automatically disconnect CH340C, thereby reducing the continuous power consumption of CH340 when USB is not plugged in;
5. An SD card has been added to provide more expandability;
6. The main power supply LDO is replaced with HE9073 to further reduce quiescent current and thereby further reduce power consumption. And it can provide a large current, so tantalum capacitors can not be connected in parallel to prevent excessive instantaneous power consumption leading to power failure and restart;
7. The charging chip is replaced with TP5000 to further reduce the operating temperature and reduce current backflow, further reducing power consumption;
8. The 32.768K crystal oscillator is externally installed to further reduce power consumption in sleep state;
9. All peripherals are equipped with MOS tubes to control the power supply and are turned off when not in use to further reduce power consumption;
10. Fixed the bug that the battery power detection circuit would leak when it is shut down.

The board has been verified, and the corresponding first version of the firmware will probably be completed after I start school. I don’t recommend that you build the board at this time (maybe I will modify some functions or pins). I released it for some personal reasons.