30 lines
1.2 KiB
Markdown
30 lines
1.2 KiB
Markdown
# TinyWetter
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TinyWetter is a small indoor weather station that provides info about
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temperature, relative humidity and atmospheric pressure by using the bmp280
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and si7021 sensors. It uses a Digispark with the [I2C-Tiny-USB] library
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to make the sensors available as i2c devices under linux (i.a.) over USB.
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## board
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The board is designed in KiCad and uses a single sided pcb layout that
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mostly functions as a cross connect for the daughter boards with the
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sensors and the Digispark. The LED is used as a cheap "voltage regulator"
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to provide 3.3V for the sensors from the 5V of the USB connection. Be
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careful to not use any funtions that require a large current like the
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heater element of the si7021, because that would likely kill the LED.
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## driver
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The driver is written in rust and can be compiled using `cargo build`. It
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uses the i2c-dev kernel interface (`modprobe i2c-dev` to load the module)
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to access the i2c devices. Given the device path `/dev/ic2-##` and the
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current altitude, it reads the current values from the sensors and outputs
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the temperature, the relative humidity and the pressure at sea level. Use
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`-v` to see more details.
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[I2C-Tiny-USB]: https://github.com/harbaum/I2C-Tiny-USB
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