Preface

This work uses Tuya Smart MCU SDK for development. The MCU uses ST's STM32L051K8U6~~ Fortunately, the price of this MCU is still acceptable. As for the module, considering low power consumption, ZigBee module is used. The screen uses HINK's 2.13-inch ink screen (the same 2.13-inch black and white model from Wei Xue). Of course, this work requires a Tuya smart gateway to use it.

Component selection

basic skills

1. Time display, refreshed every minute (24-hour automatic online time adjustment)
2. Temperature and humidity display, refreshed in half an hour and reported to the cloud
3. Equipment automation and network disconnection automation can be realized through Tuya Smart Platform
4. OTA functions can be realized through Tuya Smart Platform

Finished product effect

Low power consumption

Most of the time in this work is spent on power consumption, using 4 PMOS to control SPI FLASH, ink screen, module and battery voltage measurement circuit respectively. When the corresponding device is not needed, turn off the power supply to reduce unnecessary power consumption. The MCU wakes up through the RTC alarm clock, initializes the SPI and necessary GPIO and refreshes the screen update time. When the update is completed, the MCU sets the GPIO to analog input to reduce unnecessary power consumption. At present, the sleep current can be pressed at an average of about 35ua (when the module is powered on for a long time).   Of course, this current can still be pressed. If the module power supply is controlled, the sleep current can be pressed to 2.7-3ua. (LDO quiescent current + SHT30 + MCU sleep current)

shell

The shell is drawn using fusion 360. The PCB model is temporarily exported using Altium Designer because Lichuang EDA cannot yet export the step file model. The effect of a little rendering . With the PCB model, painting the casing can be done twice the result with half the effort. At least there is no need for calipers to measure the PCB. Picture of the finished shell. Rendering effect after physical assembly.

Work demonstration

https://www.bilibili.com/video/BV1Pz4y117Rv

Later gameplay

The PCB of this work is compatible with the Tuya smart WIFI module. You can weld the WIFI module and transplant the Tuya WIFI MCU SDK for use on the PCB, and the weather can be displayed on the ink screen. If you have any commercial or profit-making ideas, please leave! ! ! Open source is not free money. Please learn independently and grow together