Initial readme

README.md

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+# Door Control
+
+A project to interface an electronic door lock actuator by Abus with a PC using
+an Adafruit Feather STM32F405 Express.
+
+## Goals
+
+- USB-serial converter @ 115200 baud to pass through commands to an external
+  NXP532 NFC controller. This will be used to authenticate people who want to
+  open the door.
+- Readout of the current door state. This is done by connecting to the two
+  outputs of the rotary encoder and integrating the changes.
+- Opening and closing the door by simulating presses of two buttons.
+
+## Wiring
+
+TODO. Add pictures and stuff.
+
+## Communication
+
+Endpoint 3 is the serial bridge to the NFC controller and should show up as e.g.
+/dev/serial/by-id/usb-Imaginaerraum.de_DoorControl_433632201350535727003F0-if03
+(depending on the ID of the STM32F405).
+
+Endpoint 1 is another serial interface and used for all other functions.
+
+Command characters:
+- 'B': Print the battery voltage
+- 'C': Closes the door
+- 'O': Opens the door
+- 'R': Print the encoder position
+
+Currently, a change in the encoder value will be communicated immediately, as
+"pos: %d\r\n", the same format returned by the 'R' command.