man4/mouse.4

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  26 .TH MOUSE 4 2016-10-08 "Linux" "Linux Programmer's Manual"
  27 .SH NAME
  28 mouse \- serial mouse interface
  29 .SH CONFIGURATION
  30 Serial mice are connected to a serial RS232/V24 dialout line, see
  31 .BR ttyS (4)
  32 for a description.
  33 .SH DESCRIPTION
  34 .SS Introduction
  35 The pinout of the usual 9 pin plug as used for serial mice is:
  36 .PP
  37 .TS
  38 center;
  39 r c l.
  40 pin     name    used for
  41 2       RX      Data
  42 3       TX      \-12 V, Imax = 10 mA
  43 4       DTR     +12 V, Imax = 10 mA
  44 7       RTS     +12 V, Imax = 10 mA
  45 5       GND     Ground
  46 .TE
  47 .PP
  48 This is the specification, in fact 9 V suffices with most mice.
  49 .PP
  50 The mouse driver can recognize a mouse by dropping RTS to low and raising
  51 it again.
  52 About 14 ms later the mouse will send 0x4D (\(aqM\(aq) on the data line.
  53 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
  54 0x33 (\(aq3\(aq).
  55 .PP
  56 The relative mouse movement is sent as
  57 .I dx
  58 (positive means right)
  59 and
  60 .I dy
  61 (positive means down).
  62 Various mice can operate at different speeds.
  63 To select speeds, cycle through the
  64 speeds 9600, 4800, 2400, and 1200 bit/s, each time writing the two characters
  65 from the table below and waiting 0.1 seconds.
  66 The following table shows available speeds and the strings that select them:
  67 .PP
  68 .TS
  69 center;
  70 l l.
  71 bit/s   string
  72 9600    *q
  73 4800    *p
  74 2400    *o
  75 1200    *n
  76 .TE
  77 .PP
  78 The first byte of a data packet can be used for synchronization purposes.
  79 .SS Microsoft protocol
  80 The
  81 .B Microsoft
  82 protocol uses 1 start bit, 7 data bits, no parity
  83 and one stop bit at the speed of 1200 bits/sec.
  84 Data is sent to RxD in 3-byte packets.
  85 The
  86 .IR dx
  87 and
  88 .I dy
  89 movements are sent as
  90 two's-complement,
  91 .I lb
  92 .RI ( rb )
  93 are set when the left (right)
  94 button is pressed:
  95 .PP
  96 .TS
  97 center;
  98 r c c c c c c c.
  99 byte    d6      d5      d4      d3      d2      d1      d0
 100 1       1       lb      rb      dy7     dy6     dx7     dx6
 101 2       0       dx5     dx4     dx3     dx2     dx1     dx0
 102 3       0       dy5     dy4     dy3     dy2     dy1     dy0
 103 .TE
 104 .SS 3-button Microsoft protocol
 105 Original Microsoft mice only have two buttons.
 106 However, there are some
 107 three button mice which also use the Microsoft protocol.
 108 Pressing or
 109 releasing the middle button is reported by sending a packet with zero
 110 movement and no buttons pressed.
 111 (Thus, unlike for the other two buttons, the status of the middle
 112 button is not reported in each packet.)
 113 .SS Logitech protocol
 114 Logitech serial 3-button mice use a different extension of the
 115 Microsoft protocol: when the middle button is up, the above 3-byte
 116 packet is sent.
 117 When the middle button is down a 4-byte packet is
 118 sent, where the 4th byte has value 0x20 (or at least has the 0x20
 119 bit set).
 120 In particular, a press of the middle button is reported
 121 as 0,0,0,0x20 when no other buttons are down.
 122 .SS Mousesystems protocol
 123 The
 124 .B Mousesystems
 125 protocol uses 1 start bit, 8 data bits, no parity
 126 and two stop bits at the speed of 1200 bits/sec.
 127 Data is sent to RxD in
 128 5-byte packets.
 129 .I dx
 130 is sent as the sum of the two two's-complement
 131 values,
 132 .I dy
 133 is send as negated sum of the two two's-complement
 134 values.
 135 .I lb
 136 .RI ( mb ,
 137 .IR rb )
 138 are cleared when the left (middle,
 139 right) button is pressed:
 140 .PP
 141 .TS
 142 center;
 143 r c c c c c c c c.
 144 byte    d7      d6      d5      d4      d3      d2      d1      d0
 145 1       1       0       0       0       0       lb      mb      rb
 146 2       0       dxa6    dxa5    dxa4    dxa3    dxa2    dxa1    dxa0
 147 3       0       dya6    dya5    dya4    dya3    dya2    dya1    dya0
 148 4       0       dxb6    dxb5    dxb4    dxb3    dxb2    dxb1    dxb0
 149 5       0       dyb6    dyb5    dyb4    dyb3    dyb2    dyb1    dyb0
 150 .TE
 151 .PP
 152 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
 153 were transmitted.
 154 .SS Sun protocol
 155 The
 156 .B Sun
 157 protocol is the 3-byte version of the above 5-byte
 158 Mousesystems protocol: the last two bytes are not sent.
 159 .SS MM protocol
 160 The
 161 .B MM
 162 protocol uses 1 start bit, 8 data bits, odd parity and one
 163 stop bit at the speed of 1200 bits/sec.
 164 Data is sent to RxD in 3-byte
 165 packets.
 166 .I dx
 167 and
 168 .I dy
 169 are sent as single signed values, the
 170 sign bit indicating a negative value.
 171 .I lb
 172 .RI ( mb ,
 173 .IR rb )
 174 are
 175 set when the left (middle, right) button is pressed:
 176 .PP
 177 .TS
 178 center;
 179 r c c c c c c c c.
 180 byte    d7      d6      d5      d4      d3      d2      d1      d0
 181 1       1       0       0       dxs     dys     lb      mb      rb
 182 2       0       dx6     dx5     dx4     dx3     dx2     dx1     dx0
 183 3       0       dy6     dy5     dy4     dy3     dy2     dy1     dy0
 184 .TE
 185 .SH FILES
 186 .TP
 187 .I /dev/mouse
 188 A commonly used symbolic link pointing to a mouse device.
 189 .SH SEE ALSO
 190 .BR ttyS (4),
 191 .BR gpm (8)