man4/mouse.4

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  26 .TH MOUSE 4 1996-02-10 "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 .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.
  51 About 14 ms later the mouse will send 0x4D (\(aqM\(aq) on the data line.
  52 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
  53 0x33 (\(aq3\(aq).
  54 .PP
  55 The relative mouse movement is sent as
  56 .I dx
  57 (positive means right)
  58 and
  59 .I dy
  60 (positive means down).
  61 Various mice can operate at different speeds.
  62 To select speeds, cycle through the
  63 speeds 9600, 4800, 2400, and 1200 bit/s, each time writing the two characters
  64 from the table below and waiting 0.1 seconds.
  65 The following table shows available speeds and the strings that select them:
  66 .TS
  67 center;
  68 l l.
  69 bit/s   string
  70 9600    *q
  71 4800    *p
  72 2400    *o
  73 1200    *n
  74 .TE
  75
  76 The first byte of a data packet can be used to synchronization purposes.
  77 .SS Microsoft protocol
  78 The
  79 .B Microsoft
  80 protocol uses 1 start bit, 7 data bits, no parity
  81 and one stop bit at the speed of 1200 bits/sec.
  82 Data is sent to RxD in 3-byte packets.
  83 The
  84 .IR dx
  85 and
  86 .I dy
  87 movements are sent as
  88 two's-complement,
  89 .I lb
  90 .RI ( rb )
  91 are set when the left (right)
  92 button is pressed:
  93 .TS
  94 center;
  95 r c c c c c c c.
  96 byte    d6      d5      d4      d3      d2      d1      d0
  97 1       1       lb      rb      dy7     dy6     dx7     dx6
  98 2       0       dx5     dx4     dx3     dx2     dx1     dx0
  99 3       0       dy5     dy4     dy3     dy2     dy1     dy0
 100 .TE
 101 .SS 3-button Microsoft protocol
 102 Original Microsoft mice only have two buttons.
 103 However, there are some
 104 three button mice which also use the Microsoft protocol.
 105 Pressing or
 106 releasing the middle button is reported by sending a packet with zero
 107 movement and no buttons pressed.
 108 (Thus, unlike for the other two buttons, the status of the middle
 109 button is not reported in each packet.)
 110 .SS Logitech protocol
 111 Logitech serial 3-button mice use a different extension of the
 112 Microsoft protocol: when the middle button is up, the above 3-byte
 113 packet is sent.
 114 When the middle button is down a 4-byte packet is
 115 sent, where the 4th byte has value 0x20 (or at least has the 0x20
 116 bit set).
 117 In particular, a press of the middle button is reported
 118 as 0,0,0,0x20 when no other buttons are down.
 119 .SS Mousesystems protocol
 120 The
 121 .B Mousesystems
 122 protocol uses 1 start bit, 8 data bits, no parity
 123 and two stop bits at the speed of 1200 bits/sec.
 124 Data is sent to RxD in
 125 5-byte packets.
 126 .I dx
 127 is sent as the sum of the two two's-complement
 128 values,
 129 .I dy
 130 is send as negated sum of the two two's-complement
 131 values.
 132 .I lb
 133 .RI ( mb ,
 134 .IR rb )
 135 are cleared when the left (middle,
 136 right) button is pressed:
 137 .TS
 138 center;
 139 r c c c c c c c c.
 140 byte    d7      d6      d5      d4      d3      d2      d1      d0
 141 1       1       0       0       0       0       lb      mb      rb
 142 2       0       dxa6    dxa5    dxa4    dxa3    dxa2    dxa1    dxa0
 143 3       0       dya6    dya5    dya4    dya3    dya2    dya1    dya0
 144 4       0       dxb6    dxb5    dxb4    dxb3    dxb2    dxb1    dxb0
 145 5       0       dyb6    dyb5    dyb4    dyb3    dyb2    dyb1    dyb0
 146 .TE
 147
 148 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
 149 were transmitted.
 150 .SS Sun protocol
 151 The
 152 .B Sun
 153 protocol is the 3-byte version of the above 5-byte
 154 Mousesystems protocol: the last two bytes are not sent.
 155 .SS MM protocol
 156 The
 157 .B MM
 158 protocol uses 1 start bit, 8 data bits, odd parity and one
 159 stop bit at the speed of 1200 bits/sec.
 160 Data is sent to RxD in 3-byte
 161 packets.
 162 .I dx
 163 and
 164 .I dy
 165 are sent as single signed values, the
 166 sign bit indicating a negative value.
 167 .I lb
 168 .RI ( mb ,
 169 .IR rb )
 170 are
 171 set when the left (middle, right) button is pressed:
 172 .TS
 173 center;
 174 r c c c c c c c c.
 175 byte    d7      d6      d5      d4      d3      d2      d1      d0
 176 1       1       0       0       dxs     dys     lb      mb      rb
 177 2       0       dx6     dx5     dx4     dx3     dx2     dx1     dx0
 178 3       0       dy6     dy5     dy4     dy3     dy2     dy1     dy0
 179 .TE
 180 .SH FILES
 181 .TP
 182 .I /dev/mouse
 183 A commonly used symlink pointing to a mouse device.
 184 .SH SEE ALSO
 185 .BR ttyS (4),
 186 .BR gpm (8)