man4/mouse.4

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   3 .\" This manpage is Copyright (C) 1996 Michael Haardt.
   4 .\" Updates Nov 1998, Andries Brouwer
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  25 .TH MOUSE 4 1996-02-10 "Special files" "Linux Programmer's Manual"
  26 .SH NAME
  27 mouse \- serial mouse interface
  28 .SH CONFIG
  29 Serial mice are connected to a serial RS232/V24 dialout line, see
  30 .BR ttys (4)
  31 for a description.
  32 .SH DESCRIPTION
  33 .SS Introduction
  34 The pinout of the usual 9 pin plug as used for serial mice is:
  35
  36 .TS
  37 center;
  38 r c l.
  39 pin     name    used for
  40 2       RX      Data
  41 3       TX      -12 V, Imax = 10 mA
  42 4       DTR     +12 V, Imax = 10 mA
  43 7       RTS     +12 V, Imax = 10 mA
  44 5       GND     Ground
  45 .TE
  46
  47 This is the specification, in fact 9 V suffices with most mice.
  48 .PP
  49 The mouse driver can recognize a mouse by dropping RTS to low and raising
  50 it again.  About 14 ms later the mouse will send 0x4D ('M') on the data line.
  51 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
  52 0x33 ('3').
  53 .PP
  54 The relative mouse movement is sent as \fIdx\fP (positive means right)
  55 and \fIdy\fP (positive means down).  Various mice can operate at different
  56 speeds.  To select speeds, cycle through the
  57 speeds 9600, 4800, 2400 and 1200 bit/s, each time writing the two characters
  58 from the table below and waiting 0.1 seconds.  The following table shows
  59 available speeds and the strings that select them:
  60
  61 .TS
  62 center;
  63 l l.
  64 bit/s   string
  65 9600    *q
  66 4800    *p
  67 2400    *o
  68 1200    *n
  69 .TE
  70
  71 The first byte of a data packet can be used to synchronisation purposes.
  72 .SS "Microsoft protocol"
  73 The \fBMicrosoft\fP protocol uses 1 start bit, 7 data bits, no parity
  74 and one stop bit at the speed of 1200 bits/sec.  Data is sent to RxD in
  75 3-byte packets.  The \fIdx\fP and \fIdy\fP movements are sent as
  76 two's-complement, \fIlb\fP (\fIrb\fP) are set when the left (right)
  77 button is pressed:
  78
  79 .TS
  80 center;
  81 r c c c c c c c.
  82 byte    d6      d5      d4      d3      d2      d1      d0
  83 1       1       lb      rb      dy7     dy6     dx7     dx6
  84 2       0       dx5     dx4     dx3     dx2     dx1     dx0
  85 3       0       dy5     dy4     dy3     dy2     dy1     dy0
  86 .TE
  87 .SS "3-button Microsoft protocol"
  88 Original Microsoft mice only have two buttons.  However, there are some
  89 three button mice which also use the Microsoft protocol.  Pressing or
  90 releasing the middle button is reported by sending a packet with zero
  91 movement and no buttons pressed.
  92 (Thus, unlike for the other two buttons, the status of the middle
  93 button is not reported in each packet.)
  94 .SS "Logitech protocol"
  95 Logitech serial 3-button mice use a different extension of the
  96 Microsoft protocol: when the middle button is up, the above 3-byte
  97 packet is sent. When the middle button is down a 4-byte packet is
  98 sent, where the 4th byte has value 0x20 (or at least has the 0x20
  99 bit set). In particular, a press of the middle button is reported
 100 as 0,0,0,0x20 when no other buttons are down.
 101 .SS "Mousesystems protocol"
 102 The \fBMousesystems\fP protocol uses 1 start bit, 8 data bits, no parity
 103 and two stop bits at the speed of 1200 bits/sec.  Data is sent to RxD in
 104 5-byte packets.  \fIdx\fP is sent as the sum of the two two's-complement
 105 values, \fIdy\fP is send as negated sum of the two two's-complement
 106 values.  \fIlb\fP (\fImb\fP, \fIrb\fP) are cleared when the left (middle,
 107 right) button is pressed:
 108
 109 .TS
 110 center;
 111 r c c c c c c c c.
 112 byte    d7      d6      d5      d4      d3      d2      d1      d0
 113 1       1       0       0       0       0       lb      mb      rb
 114 2       0       dxa6    dxa5    dxa4    dxa3    dxa2    dxa1    dxa0
 115 3       0       dya6    dya5    dya4    dya3    dya2    dya1    dya0
 116 4       0       dxb6    dxb5    dxb4    dxb3    dxb2    dxb1    dxb0
 117 5       0       dyb6    dyb5    dyb4    dyb3    dyb2    dyb1    dyb0
 118 .TE
 119
 120 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
 121 were transmitted.
 122 .SS "Sun protocol"
 123 The \fBSun\fP protocol is the 3-byte version of the above 5-byte
 124 Mousesystems protocol: the last two bytes are not sent.
 125 .SS "MM protocol"
 126 The \fBMM\fP protocol uses 1 start bit, 8 data bits, odd parity and one
 127 stop bit at the speed of 1200 bits/sec.  Data is sent to RxD in 3-byte
 128 packets.  \fIdx\fP and \fIdy\fP are sent as single signed values, the
 129 sign bit indicating a negative value.  \fIlb\fP (\fImb\fP, \fIrb\fP) are
 130 set when the left (middle, right) button is pressed:
 131
 132 .TS
 133 center;
 134 r c c c c c c c c.
 135 byte    d7      d6      d5      d4      d3      d2      d1      d0
 136 1       1       0       0       dxs     dys     lb      mb      rb
 137 2       0       dx6     dx5     dx4     dx3     dx2     dx1     dx0
 138 3       0       dy6     dy5     dy4     dy3     dy2     dy1     dy0
 139 .TE
 140
 141 .SH FILES
 142 .TP
 143 .I /dev/mouse
 144 A commonly used symlink pointing to a mouse device.
 145
 146 .SH "SEE ALSO"
 147 .BR ttys (4),
 148 .BR gpm (8)