Nunchuck

From Wiimote Wiki

The Nunckuck conforms to the standard memory map described on Extensions. The following all refer to decrypted data:

Identifier: 0x00, 0x00.

Data format (byte numbers are within EXT data in reports):

BYTE	BIT 7	6	5	4	3	2	1	BIT 0
0	STICK.X
1	STICK.Y
2	XLR.X[9:2]
3	XLR.Y[9:2]
4	XLR.Z[9:2]
5	XLR.Z[1:0]		XLR.Y[1:0]		XLR.X[1:0]		!C	!Z

Note that buttons bits are active-low.

Clibration data (relative to 0xA40020, repeated at 0xA40030):

OFFSET	BIT 7	6	5	4	3	2	1	BIT 0
00	XLR.X.ZERO[9:2]
01	XLR.Y.ZERO[9:2]
02	XLR.Z.ZERO[9:2]
03	XLR.?.ZERO[1:0]		XLR.?.ZERO[1:0]		XLR.?.ZERO[1:0]		XLR.?.ZERO[1:0]
04	XLR.X.ONEG[9:2]
05	XLR.Y.ONEG[9:2]
06	XLR.Z.ONEG[9:2]
07	XLR.?.ONEG[1:0]		XLR.?.ONEG[1:0]		XLR.?.ONEG[1:0]		XLR.?.ONEG[1:0]
08	STICK.X.MAX
09	STICK.X.MIN
0A	STICK.X.ZERO
0B	STICK.Y.MAX
0C	STICK.Y.MIN
0D	STICK.Y.ZERO
0E	?	?	?	?	?	?	?	?
0F	?	?	?	?	?	?	?	?

Mapping for LSBs of accelerometer calibration data is not known. The last two bytes may be a checksum.