2 .\" This manpage is Copyright (C) 1996 Michael Haardt.
3 .\" Updates Nov 1998, Andries Brouwer
5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
6 .TH mouse 4 (date) "Linux man-pages (unreleased)"
8 mouse \- serial mouse interface
10 Serial mice are connected to a serial RS232/V24 dialout line, see
15 The pinout of the usual 9 pin plug as used for serial mice is:
22 3 TX \-12 V, Imax = 10 mA
23 4 DTR +12 V, Imax = 10 mA
24 7 RTS +12 V, Imax = 10 mA
28 This is the specification, in fact 9 V suffices with most mice.
30 The mouse driver can recognize a mouse by dropping RTS to low and raising
32 About 14 ms later the mouse will send 0x4D (\[aq]M\[aq]) on the data line.
33 After a further 63 ms, a Microsoft-compatible 3-button mouse will send
36 The relative mouse movement is sent as
38 (positive means right)
41 (positive means down).
42 Various mice can operate at different speeds.
43 To select speeds, cycle through the
44 speeds 9600, 4800, 2400, and 1200 bit/s, each time writing the two characters
45 from the table below and waiting 0.1 seconds.
46 The following table shows available speeds and the strings that select them:
58 The first byte of a data packet can be used for synchronization purposes.
59 .SS Microsoft protocol
62 protocol uses 1 start bit, 7 data bits, no parity
63 and one stop bit at the speed of 1200 bits/sec.
64 Data is sent to RxD in 3-byte packets.
73 are set when the left (right)
79 byte d6 d5 d4 d3 d2 d1 d0
80 1 1 lb rb dy7 dy6 dx7 dx6
81 2 0 dx5 dx4 dx3 dx2 dx1 dx0
82 3 0 dy5 dy4 dy3 dy2 dy1 dy0
84 .SS 3-button Microsoft protocol
85 Original Microsoft mice only have two buttons.
86 However, there are some
87 three button mice which also use the Microsoft protocol.
89 releasing the middle button is reported by sending a packet with zero
90 movement and no buttons pressed.
91 (Thus, unlike for the other two buttons, the status of the middle
92 button is not reported in each packet.)
94 Logitech serial 3-button mice use a different extension of the
95 Microsoft protocol: when the middle button is up, the above 3-byte
97 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
100 In particular, a press of the middle button is reported
101 as 0,0,0,0x20 when no other buttons are down.
102 .SS Mousesystems protocol
105 protocol uses 1 start bit, 8 data bits, no parity,
106 and two stop bits at the speed of 1200 bits/sec.
107 Data is sent to RxD in
110 is sent as the sum of the two two's-complement
113 is send as negated sum of the two two's-complement
118 are cleared when the left (middle,
119 right) button is pressed:
124 byte d7 d6 d5 d4 d3 d2 d1 d0
126 2 0 dxa6 dxa5 dxa4 dxa3 dxa2 dxa1 dxa0
127 3 0 dya6 dya5 dya4 dya3 dya2 dya1 dya0
128 4 0 dxb6 dxb5 dxb4 dxb3 dxb2 dxb1 dxb0
129 5 0 dyb6 dyb5 dyb4 dyb3 dyb2 dyb1 dyb0
132 Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
137 protocol is the 3-byte version of the above 5-byte
138 Mousesystems protocol: the last two bytes are not sent.
142 protocol uses 1 start bit, 8 data bits, odd parity, and one
143 stop bit at the speed of 1200 bits/sec.
144 Data is sent to RxD in 3-byte
149 are sent as single signed values, the
150 sign bit indicating a negative value.
155 set when the left (middle, right) button is pressed:
160 byte d7 d6 d5 d4 d3 d2 d1 d0
161 1 1 0 0 dxs dys lb mb rb
162 2 0 dx6 dx5 dx4 dx3 dx2 dx1 dx0
163 3 0 dy6 dy5 dy4 dy3 dy2 dy1 dy0
168 A commonly used symbolic link pointing to a mouse device.