Mouse IO

Communications Protocols

from J.E. Davis posted by Peter Tiang

1. PC Mouse Systems

   Serial UART: 1200 baud, data=8,start=1,parity=none
   Mouse Protocol of Transmission
           bit:    7  6  5  4  3  2  1  0
   byte 1  (sync)  1  0  0  0  0  L  M  R      (0=depressed button)
   byte 2  (dX)    x7 x6 x5 x4 x3 x2 x1 x0     (bit 7 -> 0=pos,1=neg)
   byte 3  (dY)    y7 y6 y5 y4 y3 y2 y1 y0
   byte 4  (dX')   x7 x6 x5 x4 x3 x2 x1 x0
   byte 5  (dY')   y7 y6 y5 y4 y3 y2 y1 y0
   Notes:  - all bytes are two's complement binary
           - dX, dY  = relative moves after last transmission
           - dX',dY' = relative moves since dX, dY were transmitted
   
   

2. Microsoft Mouse

   Serial UART: 1200 baud, data=7,stop=1,parity=none
   Mouse Protocol of Transmission (normal mode)
           bit:    7  6  5  4  3  2  1  0
   byte 1  (sync)  0  1  L  R  y7 y6 x7 x6    (1=depressed button)
   byte 2  (dX)    0  0 x5 x4 x3 x2 x1 x0     (MSB-> 0=pos,1=neg)
   byte 3  (dY)    0  0 y5 y4 y3 y2 y1 y0
   Notes:  - all moves bytes are two's complement binary
             (you must collect all bits together)
   

Wheel Motion Sensors

Mechanical mice use a Quadrature Encoder position sensor attached to a shaft that rubs against the ball.

Jinxs' 16F84 4 button directional controller pluges in place of an MS Mouse

See also:

• http://www.embeddedlinks.com/chipdir/oth/mouse.txt
• http://www.4qd.co.uk/faq/meece.html
• http://www.krystal.com/nsfaq/Q.12.html
• http://www.hut.fi/~then/mytexts/mouse.html
• http://32.97.166.75/imouse/

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