add description of the BLE data format

BadgeBLE.md

@@ -0,0 +1,47 @@
+## Badge Data Format for BLE
+
+### Connection Information
+
+The pixel data is transferred to the badge via BLE. The badge advertizes the name "LSLED" and uses a vendor specific service/characteristic:
+
+- Service-UUID: 0000fee0-0000-1000-8000-00805f9b34fb
+- Characteristic: 0000fee1-0000-1000-8000-00805f9b34fb
+
+The characteristic accepts 16 byte long data packets.
+
+### Data Format
+
+The badge supports up to 8 bitmaps which can have various features enabled.
+
+| format    | data      | description  |
+| --------- | --------- | ------------ |
+| uint8[6]  | header    | fixed header: "wang\0\0" |
+| uint8     | flash     | bitfield describing which of the 8 bitmaps are flashing |
+| uint8     | marquee   | bitfield describing which of the 8 bitmaps feature an animated border |
+| uint8[8]  | modes     | speed+mode for each of the 8 bitmaps. See below. |
+| uint16[8] | sizes     | count of 8 pixel wide chunks for each bitmap (Big endian) |
+| uint8[6]  | padding   | 6 bytes zeroes of padding
+| uint8[6]  | timestamp | one byte each for (year % 256), month, day, hour, minute, second. Purpose unclear.
+| uint8[4]  | padding   | 4 bytes zeroes of padding
+| uint8[16] | separator | zeroes to separate header from bitmap data |
+| uint8[11]\*N | bitmapdata | image data for all bitmaps. Each bitmap consists of a number of 11 byte chunks describing an 8x11 bitmap, each byte describes 8 pixels, starting with the most significant bit. The number of chunks is listed in the "sizes" fields above, N = sum(sizes). |
+| uint8[?] | padding | the last 16-byte block of bitmap data is padded with zeroes. |
+| uint8[16] | end-of-message | the last write to the characteristic is just zeroes. |
+
+
+#### Modes
+
+The "mode" bytes are a combination of two 4 bit values. The high nibble describes the animation speed in the range from 0 (slowest) to 7 (highest). The low nibble describes the animation to use:
+
+| mode | animation         |
+|------|-------------------|
+| 0x00 | scroll leftwards  |
+| 0x01 | scroll rightwards |
+| 0x02 | scroll up         |
+| 0x03 | scroll down       |
+| 0x04 | fixed             |
+| 0x05 | "snowflake"       |
+| 0x06 | "picture"         |
+| 0x07 | "animation"       |
+| 0x08 | "laser"           |
+

README.md

@@ -47,7 +47,7 @@ The 2 buttons configuration:
 
 ### Upload Protocol
 
-Sorry, you'll have to dive into code here :/
+Here is some documentation on the [BLE package format](BadgeBLE.md). There still are some unclear parts, but it seems to work.
 
 See original [led-name-badge-ls32](https://github.com/fossasia/led-name-badge-ls32) for USB update protocol reverse engineering