HW-SPAR3E-SK-UK-G Xilinx Inc, HW-SPAR3E-SK-UK-G Datasheet - Page 66

• Manufacturer Part Number: HW-SPAR3E-SK-UK-G
• Description: KIT STARTER SPARTAN-3E
• Manufacturer: Xilinx Inc

Specifications of HW-SPAR3E-SK-UK-G

• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Development Tool Type: Hardware / Software - Starter Kit
• Mcu Supported Families: Spartan-3E
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: HW-SPAR3E-SK-US-UK-G; HW-SPAR3E-SK-US-UK-G

Chapter 8: PS/2 Mouse/Keyboard Port
Mouse
66
Idle state
1
0
L
Start bit
R
Mouse status byte
0
1 XS YS XV YV P
A mouse generates a clock and data signal when moved; otherwise, these signals remain
High, indicating the Idle state. Each time the mouse is moved, the mouse sends three 11-bit
words to the host. Each of the 11-bit words contains a ‘0’ start bit, followed by 8 data bits
(LSB first), followed by an odd parity bit, and terminated with a ‘1’ stop bit. Each data
transmission contains 33 total bits, where bits 0, 11, and 22 are ‘0’ start bits, and bits 10, 21,
and 32 are ‘1’ stop bits. The three 8-bit data fields contain movement data as shown in
Figure
A PS/2-style mouse employs a relative coordinate system (see
moving the mouse to the right generates a positive value in the X field, and moving to the
left generates a negative value. Likewise, moving the mouse up generates a positive value
in the Y field, and moving it down represents a negative value. The XS and YS bits in the
status byte define the sign of each value, where a ‘1’ indicates a negative value.
The magnitude of the X and Y values represent the rate of mouse movement. The larger the
value, the faster the mouse is moving. The XV and YV bits in the status byte indicate when
the X or Y values exceed their maximum value, an overflow condition. A ‘1’ indicates
when an overflow occurs. If the mouse moves continuously, the 33-bit transmissions repeat
every 50 ms or so.
The L and R fields in the status byte indicate Left and Right button presses. A ‘1’ indicates
that the associated mouse button is being pressed.
Figure 8-5: The Mouse Uses a Relative Coordinate System to Track Movement
8-4. Data is valid at the falling edge of the clock, and the clock period is 20 to 30 kHz.
Stop bit
-X values
Figure 8-4: PS/2 Mouse Transaction
(XS=1)
1
Start bit
0
X0 X1 X2 X3 X4 X5 X6 X7 P
X direction byte
www.xilinx.com
+Y values
-Y values
Stop bit
Spartan-3E FPGA Starter Kit Board User Guide
(YS=0)
(YS=1)
1
Start bit
0
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 P
Y direction byte
UG230 (v1.2) January 20, 2011
Figure
UG230_c8_05_021806
+X values
8-5), wherein
(XS=0)
Stop bit
UG230_c8_04_021806
Idle state
1
R