[Tuya Smart] Temperature and Humidity Clock-340465A

Wall-mounted, typec power supply, WiFi networking, 1602 display, temporarily ready to display time, temperature and humidity, with a buzzer to remind when temperature and humidity exceed limits. Supports built-in temperature and humidity sensors and external short-distance temperature and humidity sensors. The technology is not good. As of 21/3/7 23:30, only some functions have been made. Only the backlight switch is written on the button, the menu is not written, the other external temperature and humidity sensor is not written, and the onboard real-time clock is not written. It doesn't work with Tuya Smart either. Some of the problems encountered:

1. The IIC pull-up is not drawn and can only be pulled up using the internal resistor.
2. AHT20 is not easy to solder.
3. There is no switch for debugging the microcontroller, and the download process is very troublesome.
4. The crystal oscillator of the microcontroller is too high, and the gap between the 1602 and the board is not enough, so it needs to be adjusted.
5. 1602 uses the 5V version, but the power supply of the microcontroller is 3.3V. There is no problem in short-term testing, but I don’t know if there are any hidden dangers in the long term.
6. The screws I bought at Lichuang Mall are not magnetic, but they are rusty. .
7. The white solder mask can easily rub off the solder mask layer.