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This project displays information about the environment on an ST7789 display. There’s a text version of the data and a simple trend graph of the dust/pollen data. The sensors used are as follows:
Pressure/Temperature: BMP280
Light : TLS2561
Dust : DM501A

The BMP280 and TLS2561 connect back to the STM32G071 over the I2C1 bus. The DM501A light sensor connects back to a GPIO pin. This pin is sampled at 1kHz. When a dust particle is detected in the sensor this pin is driven low. The program simply counts the number of milliseconds (samples) that this pin is low over a 1 minute interval and displays this figure.

Environmental information is sent back to a host PC using a UART. It is also written to the ST7789 display.

Code is available over here on github.