Manpage of MOUSE
MOUSESection: Linux Programmer's Manual (4)
NAMEmouse - serial mouse interface
CONFIGURATIONSerial mice are connected to a serial RS232/V24 dialout line, see ttyS(4) for a description.
IntroductionThe pinout of the usual 9 pin plug as used for serial mice is:
|3||TX||-12 V, Imax = 10 mA|
|4||DTR||+12 V, Imax = 10 mA|
|7||RTS||+12 V, Imax = 10 mA|
This is the specification, in fact 9 V suffices with most mice.
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 (aqMaq) on the data line. After a further 63 ms, a Microsoft-compatible 3-button mouse will send 0x33 (aq3aq).
The relative mouse movement is sent as dx(positive means right) and dy(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:
Microsoft protocolThe Microsoftprotocol 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 dxand dymovements are sent as two's-complement, lb(rb) are set when the left (right) button is pressed:
3-button Microsoft protocolOriginal 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 button is not reported in each packet.)
Logitech protocolLogitech 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 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 as 0,0,0,0x20 when no other buttons are down.
Mousesystems protocolThe Mousesystemsprotocol 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 5-byte packets. dxis sent as the sum of the two two's-complement values, dyis send as negated sum of the two two's-complement values. lb(mb, rb) are cleared when the left (middle, right) button is pressed:
Sun protocolThe Sunprotocol is the 3-byte version of the above 5-byte Mousesystems protocol: the last two bytes are not sent.
MM protocolThe MMprotocol 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 packets. dxand dyare sent as single signed values, the sign bit indicating a negative value. lb(mb, rb) are set when the left (middle, right) button is pressed:
- A commonly used symbolic link pointing to a mouse device.
SEE ALSOttyS(4), gpm(8)
- SEE ALSO
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