X-Dream Bike serial communications (input/output packet content)

[drmason789]

The data comes in from the serial port at baud rate 115200 as 32-character text strings of characters 0-9 and a-f (lower case), i.e. hexadecimal text for 16 bytes. The bike this was measured on delivers packets at a rate of about 1 every 13ms.

Here's what I have so far. Many thanks to the author of this repo for a helpful start.

                                     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
          (00) Header (0x6a) --------+  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
          (01) Steering ----------------+  |  |  |  |  |  |  |  |  |  |  |  |  |  |
          (02) Unknown (0x80)--------------+  |  |  |  |  |  |  |  |  |  |  |  |  |
          (03) Crank position ----------------+  |  |  |  |  |  |  |  |  |  |  |  |
          (04) Right brake ----------------------+  |  |  |  |  |  |  |  |  |  |  |
          (05) Left brake --------------------------+  |  |  |  |  |  |  |  |  |  |
          (06) Unknown (0xff)--------------------------+  |  |  |  |  |  |  |  |  |
          (07) Unknown (0xff)-----------------------------+  |  |  |  |  |  |  |  |
          (08) Button flags ---------------------------------+  |  |  |  |  |  |  |
          (09) Button flags ------------------------------------+  |  |  |  |  |  |
          (0A) Crank revolution time (high byte) ------------------+  |  |  |  |  |
          (0B) Crank revolution time (low byte) ----------------------+  |  |  |  |
          (0C) Flywheel Revolution Time (high byte) ---------------------+  |  |  |
          (0D) Flywheel Revolution Time (low byte) -------------------------+  |  |
          (0E) Heart rate (BPM) -----------------------------------------------+  |
          (0F) XOR of 00 to 0E----------------------------------------------------+

Header is always 0x6a
Steering [0, 255]
Crank Position [1,60]
Left Brake [135, 250] (250 when released)
Right Brake [135, 250] (250 when released)
Button Flags are a bitmapped field. See XDreamControllerButtons.cs
Flywheel revolution time F: RPM = 600000/F approximately. #40
Crank revolution time C: RPM = 1/(C * 0.000006) approximately. #19
Heart rate is in beats per minute.
Unknowns 02, 06, 07 are always 128, 255 and 255.
0F is the XOR of the first 15 bytes.

Button flags combined into 1 16-bit unsigned integer and subtracted from 65535 form a bitmapped field:

None = 0
Seated = 8

BackGearUp = 32
BackGearDown = 64
FrontGearUp = 32768
FrontGearDown = 128

LeftArrow = 4096
RightArrow = 16384
UpArrow = 256
DownArrow = 1024

Blue = 8192
Red = 512
Green = 2048

[drmason789]

Resistance is sent to the bike in a 6-byte block of data, not rendered to text like the incoming data.

This must be resent at regular intervals, e.g. 10ms (this is a guess that works) otherwise the bike drops the resistance back to 0.

There are 250 resistance levels. Each resistance packet is as follows:

                    6a 00 00 00 00 00
00 Header (0x6a) ----+  |  |  |  |  |
01 Level (0..0xFA)------+  |  |  |  |
02 (Level+0x3C)%0xFF ------+  |  |  |
03 (Level+0x5A)%0xFF ---------+  |  |
04 (Level+0x78)%0xFF ------------+  |
05 XOR of 00..04 -------------------+