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.TH MOUSE 4 1996-02-10 "Special files" "Linux Programmer's Manual"
This is the specification, in fact 9 V suffices with most mice.
.PP
The mouse driver can recognize a mouse by dropping RTS to low and raising
-it again. About 14 ms later the mouse will send 0x4D ('M') on the data line.
+it again.
+About 14 ms later the mouse will send 0x4D ('M') on the data line.
After a further 63 ms, a Microsoft-compatible 3-button mouse will send
0x33 ('3').
.PP
The relative mouse movement is sent as \fIdx\fP (positive means right)
-and \fIdy\fP (positive means down). Various mice can operate at different
-speeds. To select speeds, cycle through the
+and \fIdy\fP (positive means down).
+Various mice can operate at different speeds.
+To select speeds, cycle through the
speeds 9600, 4800, 2400 and 1200 bit/s, each time writing the two characters
-from the table below and waiting 0.1 seconds. The following table shows
-available speeds and the strings that select them:
+from the table below and waiting 0.1 seconds.
+The following table shows available speeds and the strings that select them:
.TS
center;
l l.
The first byte of a data packet can be used to synchronisation purposes.
.SS "Microsoft protocol"
The \fBMicrosoft\fP protocol uses 1 start bit, 7 data bits, no parity
-and one stop bit at the speed of 1200 bits/sec. Data is sent to RxD in
-3-byte packets. The \fIdx\fP and \fIdy\fP movements are sent as
+and one stop bit at the speed of 1200 bits/sec.
+Data is sent to RxD in 3-byte packets.
+The \fIdx\fP and \fIdy\fP movements are sent as
two's-complement, \fIlb\fP (\fIrb\fP) are set when the left (right)
button is pressed:
.TS
3 0 dy5 dy4 dy3 dy2 dy1 dy0
.TE
.SS "3-button Microsoft protocol"
-Original Microsoft mice only have two buttons. However, there are some
-three button mice which also use the Microsoft protocol. Pressing or
+Original Microsoft mice only have two buttons.
+However, there are some
+three button mice which also use the Microsoft protocol.
+Pressing or
releasing the middle button is reported by sending a packet with zero
movement and no buttons pressed.
(Thus, unlike for the other two buttons, the status of the middle
.SS "Logitech protocol"
Logitech serial 3-button mice use a different extension of the
Microsoft protocol: when the middle button is up, the above 3-byte
-packet is sent. When the middle button is down a 4-byte packet is
+packet is sent.
+When the middle button is down a 4-byte packet is
sent, where the 4th byte has value 0x20 (or at least has the 0x20
-bit set). In particular, a press of the middle button is reported
+bit set).
+In particular, a press of the middle button is reported
as 0,0,0,0x20 when no other buttons are down.
.SS "Mousesystems protocol"
The \fBMousesystems\fP protocol uses 1 start bit, 8 data bits, no parity
-and two stop bits at the speed of 1200 bits/sec. Data is sent to RxD in
+and two stop bits at the speed of 1200 bits/sec.
+Data is sent to RxD in
5-byte packets. \fIdx\fP is sent as the sum of the two two's-complement
values, \fIdy\fP is send as negated sum of the two two's-complement
values. \fIlb\fP (\fImb\fP, \fIrb\fP) are cleared when the left (middle,
Mousesystems protocol: the last two bytes are not sent.
.SS "MM protocol"
The \fBMM\fP protocol uses 1 start bit, 8 data bits, odd parity and one
-stop bit at the speed of 1200 bits/sec. Data is sent to RxD in 3-byte
+stop bit at the speed of 1200 bits/sec.
+Data is sent to RxD in 3-byte
packets. \fIdx\fP and \fIdy\fP are sent as single signed values, the
-sign bit indicating a negative value. \fIlb\fP (\fImb\fP, \fIrb\fP) are
+sign bit indicating a negative value.
+\fIlb\fP (\fImb\fP, \fIrb\fP) are
set when the left (middle, right) button is pressed:
.TS
center;