MOUSE(4)                  Special files                  MOUSE(4)



NAME

       mouse - serial mouse interface


CONFIG

       Serial  mice  are  connected to a serial RS232/V24 dialout
       line, see ttys(4) for a description.


DESCRIPTION

   Introduction
       The pinout of the usual 9 pin plug as used for serial mice
       is:

       center;   r   c   l.   pin  name used  for  2    RX   Data
       3    TX   -12 V, Imax = 10 mA 4    DTR  +12 V, Imax  =  10
       mA 7    RTS  +12 V, Imax = 10 mA 5    GND  Ground

       This  is the specification, in fact 9 V suffices with most
       mice.

       The mouse driver can recognize a mouse by dropping RTS  to
       low  and  raising  it  again.  About 14 ms later the mouse
       will send 0x4D ('M') on the data line.  After a further 63
       ms,  a  Microsoft-compatible 3-button mouse will send 0x33
       ('3').

       The relative mouse movement is sent as dx (positive  means
       right)  and  dy  (positive  means down).  Various mice can
       operate at different  speeds.   To  select  speeds,  cycle
       through  the  speeds 9600, 4800, 2400 and 1200 bit/s, each
       time writing the two characters from the table  below  and
       waiting  0.1 seconds.  The following table shows available
       speeds and the strings that select them:

       center; l l.   bit/s     string  9600 *q  4800 *p  2400 *o
       1200 *n

       The  first byte of a data packet can be used to synchroni-
       sation purposes.

   Microsoft protocol
       The Microsoft protocol uses 1 start bit, 7 data  bits,  no
       parity  and  one  stop  bit at the speed of 1200 bits/sec.
       Data is sent to RxD in 3-byte  packets.   The  dx  and  dy
       movements  are  sent  as two's-complement, lb (rb) are set
       when the left (right) button is pressed:

       center;     r     c     c     c     c     c      c      c.
       byte d6   d5   d4   d3   d2   d1   d0
       1    1    lb   rb   dy7  dy6  dx7  dx6
       2    0    dx5  dx4  dx3  dx2  dx1  dx0
       3    0    dy5  dy4  dy3  dy2  dy1  dy0

   3-button Microsoft protocol
       Original Microsoft mice only have two  buttons.   However,



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MOUSE(4)                  Special files                  MOUSE(4)


       there  are  some  three  button  mice  which  also use the
       Microsoft protocol.  Pressing or releasing the middle but-
       ton is reported by sending a packet with zero movement and
       no buttons pressed.  (Thus, unlike for the other two  but-
       tons,  the  status of the middle button is not reported in
       each packet.)

   Logitech protocol
       Logitech serial 3-button mice use a different extension of
       the  Microsoft protocol: when the middle button is up, the
       above 3-byte packet is sent. When  the  middle  button  is
       down a 4-byte packet is sent, where the 4th byte has value
       0x20 (or at least has the 0x20 bit set). In particular,  a
       press  of the middle button is reported as 0,0,0,0x20 when
       no other buttons are down.

   Mousesystems protocol
       The Mousesystems protocol uses 1 start bit, 8  data  bits,
       no parity and two stop bits at the speed of 1200 bits/sec.
       Data is sent to RxD in 5-byte packets.  dx is sent as  the
       sum  of  the  two  two's-complement  values, dy is send as
       negated sum of the two two's-complement values.   lb  (mb,
       rb)  are  cleared  when the left (middle, right) button is
       pressed:

       center;    r    c    c    c     c     c     c     c     c.
       byte d7   d6   d5   d4   d3   d2   d1   d0
       1    1    0    0    0    0    lb   mb   rb
       2    0    dxa6 dxa5 dxa4 dxa3 dxa2 dxa1 dxa0
       3    0    dya6 dya5 dya4 dya3 dya2 dya1 dya0
       4    0    dxb6 dxb5 dxb4 dxb3 dxb2 dxb1 dxb0
       5    0    dyb6 dyb5 dyb4 dyb3 dyb2 dyb1 dyb0

       Bytes 4 and 5 describe  the  change  that  occurred  since
       bytes 2 and 3 were transmitted.

   Sun protocol
       The Sun protocol is the 3-byte version of the above 5-byte
       Mousesystems protocol: the last two bytes are not sent.

   MM protocol
       The MM protocol uses 1 start bit, 8 data bits, odd  parity
       and  one  stop bit at the speed of 1200 bits/sec.  Data is
       sent to RxD in 3-byte packets.  dx and dy are sent as sin-
       gle  signed  values,  the  sign  bit indicating a negative
       value.  lb (mb, rb) are set when the left (middle,  right)
       button is pressed:

       center;     r     c     c     c     c    c    c    c    c.
       byte d7   d6   d5   d4   d3   d2   d1   d0
       1    1    0    0    dxs  dys  lb   mb   rb
       2    0    dx6  dx5  dx4  dx3  dx2  dx1  dx0
       3    0    dy6  dy5  dy4  dy3  dy2  dy1  dy0




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MOUSE(4)                  Special files                  MOUSE(4)



FILES

       /dev/mouse
              A commonly used symlink pointing to a mouse device.



SEE ALSO

       ttys(4), gpm(8)


















































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