📝 Write README.md

README.md

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 # phoenix-upshid
 Simple driver for reading data from Phoenixtec ("Amazon Basics") UPSes written in c
+
+## why?
+A while ago I bought a UPS (Uninterruptible power supply) from Amazon Basics.
+I tried multiple drivers for it, but they all had their problems:
+- **NUT** tended to mess up the USB connection after some days to a point where you had to **unplug and re-plug the USB cable** of the UPS
+- UPower had a stable connection, battery percentage was updated in real-time, but the charging state was frozen, displaying `fully-charged` when UPS was at 5% charge or displaying `charging` when UPS was already at 100%
+
+So I tried writing dirty fixes for both of those drivers, which would reset the USB connection when detecting such problem. But it wasn't as stable as I had hoped.
+
+At the end I reverse-engineered the USB-HID protocol of the UPS and wrote my own driver for it in c, which has the reset-capability built-in. I'm not at all into c driver development, so use this at your own risk, as the license already states: "WITHOUT WARRANTY OF ANY KIND"!
+
+
+
+## how to use
+Download and extract source and compile:
+```console
+$ wget https://github.com/DrMaxNix/phoenix-upshid/archive/refs/tags/1.0.0.tar.gz
+$ tar xf 1.0.0.tar.gz
+$ cd phoenix-upshid-1.0.0
+$ gcc -o phoenix-upshid phoenix-upshid.c
+```
+
+OPTIONALLY copy to `$PATH`:
+```console
+# cp phoenix-upshid /usr/local/bin/
+```
+
+Print device data of device 06da:ffff (and try usb reset):
+```console
+# ./phoenix-upshid -a 06da:ffff
+```