Hardware.md

+**Requirements**
+- Microcontroller programmable in MicroPython 
+- Ethernet
+- USB connection
+- optional screen
+- cheap enough (so we can have a collection of spares)
+
+**Base system**
+- Raspberry Pi Pico (W)
+- Wiznet W5500 Ethernet adapter
+- Waveshare PICO LCD 1.3
+- ? USB adapter
+- 24LC32AT EEPROM 
+
+**Sensors**
+- SHT25 relative humidity and temperature sensor
+- LPS28DFW pressure sensor
+
+**Rejected hardware**
+- Waveshare 2-CH UART TO ETH 
+  - requires two UART channel for I/O – no more UARTS left on the Raspberry Pi Pico
+  - no driver for the Python standard network library 
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