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 "Linux" "Linux Programmer's Manual"
27 mouse \- serial mouse interface
29 Serial mice are connected to a serial RS232/V24 dialout line, see
34 The pinout of the usual 9 pin plug as used for serial mice is:
40 3 TX \-12 V, Imax = 10 mA
41 4 DTR +12 V, Imax = 10 mA
42 7 RTS +12 V, Imax = 10 mA
46 This is the specification, in fact 9 V suffices with most mice.
48 The mouse driver can recognize a mouse by dropping RTS to low and raising
50 About 14 ms later the mouse will send 0x4D (\(aqM\(aq) on the data line.
51 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
54 The relative mouse movement is sent as \fIdx\fP (positive means right)
55 and \fIdy\fP (positive means down).
56 Various mice can operate at different speeds.
57 To select speeds, cycle through the
58 speeds 9600, 4800, 2400 and 1200 bit/s, each time writing the two characters
59 from the table below and waiting 0.1 seconds.
60 The following table shows available speeds and the strings that select them:
71 The first byte of a data packet can be used to synchronization 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.
75 Data is sent to RxD in 3-byte packets.
76 The \fIdx\fP and \fIdy\fP movements are sent as
77 two's-complement, \fIlb\fP (\fIrb\fP) are set when the left (right)
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
87 .SS "3-button Microsoft protocol"
88 Original Microsoft mice only have two buttons.
89 However, there are some
90 three button mice which also use the Microsoft protocol.
92 releasing the middle button is reported by sending a packet with zero
93 movement and no buttons pressed.
94 (Thus, unlike for the other two buttons, the status of the middle
95 button is not reported in each packet.)
96 .SS "Logitech protocol"
97 Logitech serial 3-button mice use a different extension of the
98 Microsoft protocol: when the middle button is up, the above 3-byte
100 When the middle button is down a 4-byte packet is
101 sent, where the 4th byte has value 0x20 (or at least has the 0x20
103 In particular, a press of the middle button is reported
104 as 0,0,0,0x20 when no other buttons are down.
105 .SS "Mousesystems protocol"
106 The \fBMousesystems\fP protocol uses 1 start bit, 8 data bits, no parity
107 and two stop bits at the speed of 1200 bits/sec.
108 Data is sent to RxD in
110 \fIdx\fP is sent as the sum of the two two's-complement
111 values, \fIdy\fP is send as negated sum of the two two's-complement
113 \fIlb\fP (\fImb\fP, \fIrb\fP) are cleared when the left (middle,
114 right) button is pressed:
118 byte d7 d6 d5 d4 d3 d2 d1 d0
120 2 0 dxa6 dxa5 dxa4 dxa3 dxa2 dxa1 dxa0
121 3 0 dya6 dya5 dya4 dya3 dya2 dya1 dya0
122 4 0 dxb6 dxb5 dxb4 dxb3 dxb2 dxb1 dxb0
123 5 0 dyb6 dyb5 dyb4 dyb3 dyb2 dyb1 dyb0
126 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
129 The \fBSun\fP protocol is the 3-byte version of the above 5-byte
130 Mousesystems protocol: the last two bytes are not sent.
132 The \fBMM\fP protocol uses 1 start bit, 8 data bits, odd parity and one
133 stop bit at the speed of 1200 bits/sec.
134 Data is sent to RxD in 3-byte
136 \fIdx\fP and \fIdy\fP are sent as single signed values, the
137 sign bit indicating a negative value.
138 \fIlb\fP (\fImb\fP, \fIrb\fP) are
139 set when the left (middle, right) button is pressed:
143 byte d7 d6 d5 d4 d3 d2 d1 d0
144 1 1 0 0 dxs dys lb mb rb
145 2 0 dx6 dx5 dx4 dx3 dx2 dx1 dx0
146 3 0 dy6 dy5 dy4 dy3 dy2 dy1 dy0
151 A commonly used symlink pointing to a mouse device.