This is my first time to draw a PCB, so please be gentle.

Design of multi-functional thermometer and hygrometer with ink screen based on Tuya Smart

A multi-functional ink screen temperature and humidity meter based on STM32F103C8T6 and WBR3. It connects to the electronic ink screen through the FPC-24 interface to present the current time, temperature and humidity, weather forecast and other content; uses WS2812 colored lights to prompt information or renders the background; uses infrared tubes to achieve temperature control Control air conditioners or other equipment; built-in 64Mb Flash to store fonts, pictures and OTA firmware.

On the premise of maximizing functions, this design takes into account as much later scalability and versatility as possible, and introduces some IO ports for expansion use.

MCU and its peripheral circuits

The MCU uses STM32F103C8T6. If it is out of stock, you can consider using domestic Pin-to-Pin compatible chips instead. External high-speed crystal oscillator 8MHz, low-speed crystal oscillator 32.768KHz, automatic reset after power-on. Lead to SPI1 and SPI2 interfaces, IIC1 and IIC2 interfaces, USART1 serial port, SWD debugging serial port. The above functions can be configured as other multiplexing functions through registers or used as GPIO ports. There are two ordinary buttons KEY0 and KEY1 on the board, which are connected to PB8 and PB9 respectively for later function expansion. At the same time, there is an ordinary LED light connected to PB0.

Temperature and humidity sensor

The temperature and humidity sensor uses SHT30 and is connected to the IIC1 interface of the microcontroller.

Flash

The onboard Flash uses W25Q64, which is used to store fonts, pictures and OTA firmware, and is connected to the SPI1 interface of the microcontroller.

communication

Tuya's WBR3 module is connected to the USART2 interface of the microcontroller and is developed using the MCU SDK provided by Tuya. At the same time, USART1 is introduced for later expansion.

infrared

The infrared emitter is connected to the PA1 pin of the single chip and is used to control air conditioners or other equipment when the temperature changes.

show

The display part uses an electronic ink screen, which has the advantages of low power consumption and long brightness, and is connected through the FPC-24 interface. This drive circuit is compatible with most ink screens. If it cannot be driven, you need to change R11 to 3 ohms.