man4/mouse.4

   1 .\" This manpage is Copyright (C) 1996 Michael Haardt.
   2 .\" Updates Nov 1998, Andries Brouwer
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .TH MOUSE 4 2020-08-13 "Linux man-pages (unreleased)"
   6 .SH NAME
   7 mouse \- serial mouse interface
   8 .SH CONFIGURATION
   9 Serial mice are connected to a serial RS232/V24 dialout line, see
  10 .BR ttyS (4)
  11 for a description.
  12 .SH DESCRIPTION
  13 .SS Introduction
  14 The pinout of the usual 9 pin plug as used for serial mice is:
  15 .PP
  16 .TS
  17 center;
  18 r c l.
  19 pin     name    used for
  20 2       RX      Data
  21 3       TX      \-12 V, Imax = 10 mA
  22 4       DTR     +12 V, Imax = 10 mA
  23 7       RTS     +12 V, Imax = 10 mA
  24 5       GND     Ground
  25 .TE
  26 .PP
  27 This is the specification, in fact 9 V suffices with most mice.
  28 .PP
  29 The mouse driver can recognize a mouse by dropping RTS to low and raising
  30 it again.
  31 About 14 ms later the mouse will send 0x4D (\(aqM\(aq) on the data line.
  32 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
  33 0x33 (\(aq3\(aq).
  34 .PP
  35 The relative mouse movement is sent as
  36 .I dx
  37 (positive means right)
  38 and
  39 .I dy
  40 (positive means down).
  41 Various mice can operate at different speeds.
  42 To select speeds, cycle through the
  43 speeds 9600, 4800, 2400, and 1200 bit/s, each time writing the two characters
  44 from the table below and waiting 0.1 seconds.
  45 The following table shows available speeds and the strings that select them:
  46 .PP
  47 .TS
  48 center;
  49 l l.
  50 bit/s   string
  51 9600    *q
  52 4800    *p
  53 2400    *o
  54 1200    *n
  55 .TE
  56 .PP
  57 The first byte of a data packet can be used for synchronization purposes.
  58 .SS Microsoft protocol
  59 The
  60 .B Microsoft
  61 protocol uses 1 start bit, 7 data bits, no parity
  62 and one stop bit at the speed of 1200 bits/sec.
  63 Data is sent to RxD in 3-byte packets.
  64 The
  65 .I dx
  66 and
  67 .I dy
  68 movements are sent as
  69 two's-complement,
  70 .I lb
  71 .RI ( rb )
  72 are set when the left (right)
  73 button is pressed:
  74 .PP
  75 .TS
  76 center;
  77 r c c c c c c c.
  78 byte    d6      d5      d4      d3      d2      d1      d0
  79 1       1       lb      rb      dy7     dy6     dx7     dx6
  80 2       0       dx5     dx4     dx3     dx2     dx1     dx0
  81 3       0       dy5     dy4     dy3     dy2     dy1     dy0
  82 .TE
  83 .SS 3-button Microsoft protocol
  84 Original Microsoft mice only have two buttons.
  85 However, there are some
  86 three button mice which also use the Microsoft protocol.
  87 Pressing or
  88 releasing the middle button is reported by sending a packet with zero
  89 movement and no buttons pressed.
  90 (Thus, unlike for the other two buttons, the status of the middle
  91 button is not reported in each packet.)
  92 .SS Logitech protocol
  93 Logitech serial 3-button mice use a different extension of the
  94 Microsoft protocol: when the middle button is up, the above 3-byte
  95 packet is sent.
  96 When the middle button is down a 4-byte packet is
  97 sent, where the 4th byte has value 0x20 (or at least has the 0x20
  98 bit set).
  99 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
 103 .B Mousesystems
 104 protocol uses 1 start bit, 8 data bits, no parity,
 105 and two stop bits at the speed of 1200 bits/sec.
 106 Data is sent to RxD in
 107 5-byte packets.
 108 .I dx
 109 is sent as the sum of the two two's-complement
 110 values,
 111 .I dy
 112 is send as negated sum of the two two's-complement
 113 values.
 114 .I lb
 115 .RI ( mb ,
 116 .IR rb )
 117 are cleared when the left (middle,
 118 right) button is pressed:
 119 .PP
 120 .TS
 121 center;
 122 r c c c c c c c c.
 123 byte    d7      d6      d5      d4      d3      d2      d1      d0
 124 1       1       0       0       0       0       lb      mb      rb
 125 2       0       dxa6    dxa5    dxa4    dxa3    dxa2    dxa1    dxa0
 126 3       0       dya6    dya5    dya4    dya3    dya2    dya1    dya0
 127 4       0       dxb6    dxb5    dxb4    dxb3    dxb2    dxb1    dxb0
 128 5       0       dyb6    dyb5    dyb4    dyb3    dyb2    dyb1    dyb0
 129 .TE
 130 .PP
 131 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
 132 were transmitted.
 133 .SS Sun protocol
 134 The
 135 .B Sun
 136 protocol is the 3-byte version of the above 5-byte
 137 Mousesystems protocol: the last two bytes are not sent.
 138 .SS MM protocol
 139 The
 140 .B MM
 141 protocol uses 1 start bit, 8 data bits, odd parity, and one
 142 stop bit at the speed of 1200 bits/sec.
 143 Data is sent to RxD in 3-byte
 144 packets.
 145 .I dx
 146 and
 147 .I dy
 148 are sent as single signed values, the
 149 sign bit indicating a negative value.
 150 .I lb
 151 .RI ( mb ,
 152 .IR rb )
 153 are
 154 set when the left (middle, right) button is pressed:
 155 .PP
 156 .TS
 157 center;
 158 r c c c c c c c c.
 159 byte    d7      d6      d5      d4      d3      d2      d1      d0
 160 1       1       0       0       dxs     dys     lb      mb      rb
 161 2       0       dx6     dx5     dx4     dx3     dx2     dx1     dx0
 162 3       0       dy6     dy5     dy4     dy3     dy2     dy1     dy0
 163 .TE
 164 .SH FILES
 165 .TP
 166 .I /dev/mouse
 167 A commonly used symbolic link pointing to a mouse device.
 168 .SH SEE ALSO
 169 .BR ttyS (4),
 170 .BR gpm (8)