Appendix F: Kit Components
The PS/2 portion of the firmware handles the following requests and commands listed in the table below.
Hex Code
Command
Action
0xFF
Reset
Resets mouse to default states
0xFE
Resend
Resends last data to host
0xF6
Set Default
Sets mouse to use default parameters
0xF5
Disable
Disables the mouse
0xF4
Enable
Enables the mouse
0xF3
Set Sampling Rate
Set sampling rate to 10,20,40,60,80,100,200/second
0xF2
Read Device Type
Returns 0x00 to host, indicating the device is a mouse
0xF0
Set Remote Mode
Sets remote mode so data values are only reported after a read data command
0xEE
Set Wrap Mode
Set wrap mode until 0xFF or 0xEC is received
0xEC
Reset Wrap Mode
Reset to previous mode of operation.
0xEB
Read Data
Responds by sending a mouse report packet to host
0xEA
Set Stream Mode
Sets stream mode
0xE9
Status Request
Returns current mode, en/disabled, scaling, button, resolution, and sampling rate
information to the host.
0xE8
Set Resolution
Sets resolution to 1,2,4,8 counts/mm
0xE7
Set Scaling 2:1
Sets scaling to 2:1
0xE6
Reset Scaling
Resets scaling to 1:1
0xAA
Completion Code
Command completion code
0xFA
Peripheral ACK
Sent to acknowledge host requests
The PS/2 specification calls out the following default mouse report format. Byte 0 is the button data (1=pressed,
0=released), X and Y optics sign bits, and X and Y overflow bits. Byte 1 is the X optics data in 2’s complement format.
Byte 2 has the Y optics data in 2’s complement format. At reset or power-on the standard PS/2 reporting format is
enabled.
Bit 7
Bit 0
Byte 0
Y Overflow
X Overflow
Y sign
X sign
Always 1
Middle
Button
Right button Left button
Byte 1
X
X
X
X
X
X
X
X
Byte 2
Y
Y
Y
Y
Y
Y
Y
Y
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