Agilent Technologies ADNK-6003 Design Manual page 22

After the following sequence of commands, the wheel report format is enabled.
0xF3, 0xC8 Set Sampling Rate 200 per second
0xF3, 0x64 Set Sampling Rate 100 per second
0xF3, 0x32 Set Sampling Rate 50 per second
0xF2, 0x03 Read Device Type returns a value of 0x03
Bit 7
Byte 0 Y
Overflow
Byte 1 X
Byte 2 Y
Byte 3 Wheel*
After the Read Device Type command returns 0x03 to indicate that this is a Microsoft compatible
three button-wheel mouse, the wheel report format is enabled. After this initialization sequence,
the PS/2 wheel reporting format is enabled. The fourth byte represents the wheel data. This byte
is assigned 0x01 for forward wheel movement and 0xFF for backward wheel movement. When the
wheel is idle, this value is 0x00.
Start Bit Data Bit Data Bit
(Always 0) 0 1
The PS2 data transmission according to the PS/2 Hardware Interface Technical Reference
including eleven bits for each byte sent. The bits are sent in the following order with data valid
on the falling edge of the clock. See the PS/2 Hardware Interface Technical Reference manual for
timing information.
22
X Overflow Y sign
X X
Y Y
Wheel* Wheel*
Data Bit Data Bit Data Bit
2 3 4
X sign Always 1 Middle
Button
X X X
Y Y Y
Wheel* Wheel* Wheel*
Data Bit Data Bit
5 6
Bit 0
Right Left button
button
X X
Y Y
Wheel* Wheel*
Data Bit Odd Parity Stop Bit
7 Bit (Always 1)