Tag Data

[Tag MAC 2 bytes] [Sensor ID 4 bits] [Sensors Count 4 bits] [TO ADD : Message Length] [Sensor Data] [Sensor ID 4 bits] [Sensors Count 4 bits] [Message Length][Sensor Data]

Tag MAC :

Two last bytes of the MAC address

Sensor ID : Sensor Id type

• Internal IMU : 1
• External IMU : 2
• Trackpad : 3
• TCA9548A : 4
• SX1509 : 5
• Gun : 6
• Position : 0

Sensors Count : the count if there are multiple sensors with the same ID, like multiple IMUs

Sensor Data :

Data from the sensors, length depend on sensor type

IMU

ID : 1 for internal IMU, 2 for external

Count : 0-15

Data :

• Length [1 byte] : message length
• (Quaternion w + 1) *10 000 [2 bytes] (only positive number between from 0 to 20 000 to remap from -1 to +1)
• (Quaternion x + 1) *10 000 [2 bytes] (only positive number between from 0 to 20 000 to remap from -1 to +1)
• (Quaternion y + 1) *10 000 [2 bytes] (only positive number between from 0 to 20 000 to remap from -1 to +1)
• (Quaternion z + 1) *10 000 [2 bytes] (only positive number between from 0 to 20 000 to remap from -1 to +1)
• Acceleration X [2 bytes] : , -2048 to +2048 (/4)
• Acceleration Y [2 bytes] : -2048 to +2048 (/4)
• Acceleration Z [2 bytes] : -2048 to +2048 (/4)

Acceleration is milligauss, to get m/s2 you need to multiply the acceleration by 9.80665 / 1000

Acceleration data are given with respect to the IMU coordinates, to get acceleration in world coordinates you need to multiply the orientation quaternion by the acceleration :

acc_worldc = orientation_quat * acc_imuc

The acceleration does NOT include the gravity vector. It has already been removed.