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===USB Mouse===
A USB mouse generally emulates a PS2 mouse, except that it generates IRQs from the USB bus, and not IRQ 12. Good idea is to also select the checkbox "enable mouse capture". "Mouse toggle method" enables you to choose from a list hotkey to switch between mouse capture enabled or disabled.
 
===Bochs===
If you use bochs, and want your mouse to emulate PS2 mouse, you need to edit keyboard & mouse settings and set mouse type to either "ps2" (this is the mouse without mouse wheel button) or "imps2" (this is the mouse with mouse wheel button).
 
===PS2 Mouse -- Basic Operation (Microsoft compliant)===
Line 18 ⟶ 21:
which is which. To tell if there is any available data on port 0x60 at all, it is necessary
to read a byte from port 0x64. In that byte from port 0x64, bit number 0 (value=1) indicates that a byte is
available to be read on port 0x60. An additional bit, bit number 5 (value=0x20 or 0b00100000), indicates that this next byte
came from the mouse, if the bit is set. If you look at [[RBIL]], it says that this "mouse bit" is MCA specific,
but this is no longer true. All PCs that support PS2 mice use this bit to indicate that the incoming byte was
Line 28 ⟶ 31:
indicating the status of mouse wheels and extra buttons.
 
Mice with no scroll wheels use 3 byte packets exclusively. Mice with scroll wheeels,wheels and up to
5 buttons (currently) can send 4 byte packets, if they are initialized properly.
 
====Mouse Packet Info====
For even greater detail on Microsoft compliant PS2 mouse packets than what is presented next: reference the links below, or search for the Adam Chapweske article. For mice that are not M$-compliant, see the Linux article.
or search for the Adam Chapweske article. For mice that are not MS-compliant, see the Linux article.
 
=====Timing/Generation of Mouse Packets=====
A mouse is usually initialized to only generate movement packets at a particular rate. The default rate is 100 packets
per second, if the mouse is being moved. A mouse also generates a packet if a button is either pressed
or released. If the mouse is not moving, and no buttons are being clicked, a mouse will not generate any automatic
packets.
 
Line 46 ⟶ 50:
for deltaX and deltaY are one or two for slow movement, and perhaps 20 for very fast movement. Maximum possible
values are +255 to -256 (they are 9-bit quantities, two's complement).
The meaning of the packets is like this:
<br>
<br>
Line 57 ⟶ 60:
! Always 1
! Middle Btn
! Left Btn
! Right Btn
! Left Btn
|}
<br>
Line 89 ⟶ 92:
=====Formats of Optional 4th Packet Byte=====
If the mouse has been initalized so that its mouseID is 3 or 4, it will send a 4th byte in each packet. On all current
mice, the top two bits should be ignored. On some mice, the bits will flip between 0 and 1, based on scroll wheeelwheel
movement. If the mouse has a 4th and 5th mouse button, then their state is indicated by bit 4 (value=0x10), and bit
5 (value=0x20), respectively. Note: if the buttons <i>do not</i> exist, then these bits may flip based on scroll
Line 95 ⟶ 98:
do not exist.)
 
Currently, theThe bottom nibble (4 bits) of the 4th byte mightwill havebe one of the following values:
* 0 -- no scroll wheel movement
* 1 -- vertical scroll up one click
Line 102 ⟶ 105:
* 0xE -- horizontal scroll left one click
 
When only the vertical scrollwheel exists or has been activated, the 4th packet byte simply contains:
It will look something like this, when only 1 scroll has been activatet:
<br>
byte 4:
Line 108 ⟶ 111:
! Z movement
|}
However, if youthe mangedemouse tohas haveextra abuttons 2and scrollgets wheelinitialized ( or 5 btn) and initproperly, then it will look like this :
<br>
byte 4:
{| border="1" cellspacing="0" cellpadding="5" align="center"
! AlwaysMostly 0
! AlwaysMostly 0
! 5th btn down (pressed)
! 4th btn down (pressed)
! Z3
! Z2
Line 121 ⟶ 124:
! Z0
|}
HereWhere is Z3Z0 though Z0Z3 is a 4 bit signed value, of the Z movement (scrollscrollwheel), ifwith itthe isvalues increased/mentioned decreasedabove with(0, 1, 2, then it is the vertical scroll wheel0xE, else it is just the horizontal scroll wheel.<br>0xF)
and with the meanings listed above.
If a button is pressed, then the value for the button will be “1”, and when not pressed “0”.
 
====Non-Linear Movement====
When a user is trying to point at something on a screen, they will quickly move the mouse in the general direction
of the target, and then slow down to accurately point at it. The deltaX/Y values from the mouse packets
can be used directly, but doing that will force the user to move the mouse very far to get the cursor from one area of the
screen to another.
screen to another -- since "rapid movement" of a mouse will only generate packets with deltaX/Y values of perhaps 20.
 
One good answer is to scale the mouse movement by additional multiples, based on how fast the mouse is moving.
A better answer may be to scale the mouse movement by additional multiples, based on how fast the mouse is moving.
If the mouse is moving slowly, the scale factor can be 1 -- to allow the highest possible sensitivity. When the mouse
is (or has been) moving fast, the scale factor could be 5 or 10, to allow the cursor to move across large distances on
the screen, quickly.
 
There are many ways to do such scaling, obviously. If you are coding the driver in assembler, one suggestion might
be to use the BSR command to generate an approximate log base2 of deltaX andplus deltaY, and use that as your scaling factor.
 
====Doubleclicks====
Line 145 ⟶ 149:
 
====Timeouts/Mouse Disconnect====
If a mouse is operating normally, but is not being moved or clicked, it will not send any packets. If a mouse has been unplugged, it will also
it will also not send any packets. If you want to support "hot plugging" of PS2 mice, then you mightneed wantto know when a mouse has
become disconnected, because you will need to reinitialize it. If you have not seen any packets from the mouse for awhile,
to know when a mouse has become disconnected. So, if you
have not seen any packets from the mouse for awhile, you can query the mouse to see if it is still alive. A convenient way to do this is to send a special request for a single
way to do this is to send a request for a mouse packet (mouse command 0xEB). You will get back an ACK (0xFA) from the mouse, and then
a mouse packet (with everything set to 0, probably). Please note that you need to make sure that the 0xFA does not
cause a misalignment of your input mouse packet. Also please note that if the contents of the mouse packet are <i>not</i> 0,
Line 158 ⟶ 162:
 
===PS2 Mouse Commands===
After the PS2 Aux port has been enabled, you can send commands to the mouse. It is recommended to disable packetsautomatic while "reprogramming" the mouse.packet
streaming mode while "reprogramming" the mouse. You can do this by either sending command 0xF5 to the mouse, or disabling
the "master mouse clock" by setting bit 5 of the Compaq Status byte (see below).
 
====Waiting to Send Bytes to Port 0x60 and 0x64====
All output to port 0x60 or 0x64 must be preceded by waiting for bit 1 (value=2) of port 0x64 to become clear. Similarly, bytes cannot be read from port 0x60 until bit 0 (value=1) of port 0x64 is set. See [[PS2 Keyboard]] for further details.
bytes cannot be read from port 0x60 until bit 0 (value=1) of port 0x64 is set. See [[PS2 Keyboard]] for further details.
 
====0xD4 Byte and, Command Byte, Data Byte====
Sending a command or data byte to the mouse (to port 0x60) must be preceded by sending a 0xD4 byte to port 0x64 (with appropriate
waits on port 0x64, bit 1, before sending each output byte). Note: this 0xD4 byte does <i>not</i> generate any ACK, from
either the keyboard or mouse.
 
====Wait for ACK from Mouse====
It is required to wait until the mouse sends back the 0xFA acknowledgement byte after each command or data byte before sending the next 0xD4 (Note: reset commands might not be ACK'ed -- wait for the 0xAA after a reset).
Somenext byte (Note: reset commands generatemight 2not be ACK,'ed 1-- wait for the command,0xAA andafter 1a forreset). receivingA data.few commands require an additional
data byte, and both bytes will generate an ACK.
 
====Useful Mouse Command Set====
*Note: remember that the mouse responds to all command bytes and data bytes with an ACK (0xFA).
*Note2: the commands given in the table are sent to port 0x60. If a command needs additional byte (like sampling rate), this byte goes to port 0x60 too.
 
====Mouse Command Set====
{| border="1" cellspacing="0" cellpadding="5" align="center"
! Hex value
Line 180 ⟶ 191:
! 0xFF
! Reset
! The mouse probably sends ACK (0xFA) andplus several more bytes, then resets itself, and always sends 0xAA.
|-
! 0xFE
! Resend
! thisThis command makes the mouse sendssend its secondmost lastrecent packet to the host again.
|-
! 0xF6
! Set Defaults
! Disables streaming, sets the packet rate to 100 per second, and resolution to 4 pixels per mm.
! The mouse sends ACK (0xFA) and applies default values
|-
! 0xF5
! Disable DataPacket ReportingStreaming
! The mouse sendsstops ACKsending (0xFA)automatic and disable data reportingpackets.
|-
! 0xF4
! Enable DataPacket ReportingStreaming
! The mouse sendsstarts ACKsending (0xFA)automatic andpackets enableswhen datathe reportingmouse moves or is clicked.
|-
! 0xF3
! Set Sample Rate
! Requires an additional data byte: automatic packets per second (see below for legal values).
! The mouse sends ACK (0xFA) and waits for the next data, written to the mouse, to be the sample rate
|-
! 0xF2
! Get Device IDMouseID
! The mouse sends ACK (0xFA) and sends its current "ID", thoughwhich may change thewith DATAmouse portinitialization.
|-
! 0xEB
! Request Single Packet
! The mouse sends ACK, followed by a complete mouse packet with current data.
|-
! 0xE9
! Status Request
! The mouse sends ACK, then 3 status bytes. See below for the status byte format.
|-
! 0xE8
! Set Resolution
! Requires an additional data byte: pixels per millimeter resolution (value 0 to 3)
 
|}
 
====Additional Useless Mouse Commands====
{| border="1" cellspacing="0" cellpadding="5" align="center"
! Hex value
! Meaning
! Description
|-
! 0xF0
Line 212 ⟶ 243:
! 0xEE
! Set Wrap Mode
! The mouse sends ACK (0xFA) and then reset its movement counters, and enters warpwrap mode
|-
! 0xEC
! Reset Wrap Mode
! The mouse sends ACK, and then enters the last mode, before entering wrap mode, it also resets its movement counters
|-
! 0xEB
! Read Data
! The mouse sends ACK, followed by the first packet, and so on, until It have sent all.
|-
! 0xEA
! Set Stream Mode
! The mouse sends ACK (0xFA) and then reset its movement counters, and enters reporting mode
|-
! 0xE9
! Status Request
! The mouse sends ACK, and sends afterwards the status bytes ( 3 bytes in a row, remember to wait each time for new data)
|-
! 0xE8
! Set Resolution
! The mouse sends ACK and waits for the next data, written to the mouse, to be the resolution
|-
! 0xE7
! Set Scaling 2:1
! The mouse sends ACK and setsets non-linear scaling "2:1"
|-
! 0xE6
! Set Scaling 1:1
! The mouse sends ACK and setsets normal linear scaling "1:1"
 
|}
 
<br>
The status bytebytes lookslook like this:
<br>
Byte 1:
Line 259 ⟶ 279:
Byte 2:
{| border="1" cellspacing="0" cellpadding="5" align="center"
!resolution
!resoltion
|}
Byte 3:
Line 269 ⟶ 289:
Scaling: if it is 1, scaling 2:1 is enabled; if 0 then scaling 1:1 is enabled.<br>
 
=====Resolution, Scaling and Sample Rate=====
Definitions:
*Resolution: DeltaX or DeltaY for each millimeter of mouse movement.
*Scaling: Apply a simple non-linear distortion to mouse movement (see Non-Linear Movement, above).
*Sampling Rate: Packets the mouse can send per second.
 
=====Resolution, Scaling and Sampling rate =====
Those is some options about the mouse, when you move it, and about how many packets it can make pr second.
Resolution: this is how many packets pr millimeter movement.
Scaling: is a change to the packet reported for each millimeter.
Sampling rate: this is how many packets the mouse can send pr second.
Those “options” can (of cause) have different value, so let’s sum them up:
Resolution:
 
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|}
<br>
Scaling can either be "1:1" (linear = no scaling) or "2:1" (non-linear). This is the non-linear scaling:
For scaling, there is not many possibilities, since it can either be “1:1” or “2:1”, but looking at the scheme (below) we can see what happens if it is “2:1”
 
{| border="1" cellspacing="0" cellpadding="5" align="center"
Line 322 ⟶ 341:
!2 * Movement Counter
|}
 
<br>
SamplingSample rateRate can have the following values: (all values isare Decimal, NOT hex)<br>
{| border="1" cellspacing="0" cellpadding="5" align="center"
! value
Line 349 ⟶ 368:
!200
|}
 
*Note: human eyes don't see movement faster than 30 samples per second, and human fingers cannot click a button
that fast either. A sample rate lower than 30 will cause visibly jerky mouse movement, and may miss mousedown events.
A sample rate significantly higher than 30 will waste precious I/O bus bandwidth. You may test these things for
yourself, but sample rates of 10, 20, 100, or 200 are generally not recommended.
 
===Initializing a PS2 Mouse===
 
The PS2 mouse port on a PC is attached to the auxiliary input of the PS2 keyboard controller. That input
might be disabled at bootup, and needs to be enabled. It is usually also desirable to have the mouse generate
Line 359 ⟶ 382:
 
====PS/2 Device Unplugging/Hot Plugging====
SomeThe idiotperson who created the PS/2 device specs did not specify that PS/2 devices can be unplugged and replugged
while the computer remains turned on ("hot plugging"). A long time ago, some other idiotspeople actually designed motherboards that would
be slightly damaged if PS2 hot plugging occurs. However, mice and keyboards have cords that were made to be tripped over,
and sometimes it is very logical to try moving a mouse from one machine to another, temporarily, without powering
theboth systems down. So all computers made in the last 15 years should, in fact, support hot plugging of PS2 devices.
When a mouse is plugged into a running system, it may send a 0xAA, then a 0x00 byte, and then it will go into default state (see below).
 
====PS2 Aux Port Initialization====
When a computer is booted, the auxiliary port of the PS2 controller may need to be enabled, and IRQ12 may also
need to be enabled. This should only need to be done once.
 
=====Set Compaq Status/Enable IRQ12=====
Line 383 ⟶ 402:
=====Aux Input Enable Command=====
Send the Enable Auxiliary Device command (0xA8) to port 0x64. This will generate an ACK response from the <i>keyboard</i>,
which you must wait to receive. Please note that using this command is not necessary if you setsetting the bitsCompaq manually per theStatus instructionsbyte above.is
successful -- but it does no harm, either.
 
====Mouse State at Power-on====
Line 389 ⟶ 409:
the following default state:
 
* streaming mode
* packets disabled
* emulate 3 button mouse (buttons 4, 5, and scroll wheels disabled)
Line 399 ⟶ 418:
During initialization, a mouse indicates that it has various features (a scroll wheel, a 4th and 5th mouse
button) by changing its mouseID in response to initialization commands. So you send a set of mouse commands,
and then ask for the mouseID byte, with the ReadGet MouseID command (0xF2). If itthe mouseID changed, thenfrom theits mouseprevious has changed modes.value,
Thenthen sendthe anothermouse sethas of commands, and maybe changechanged modes again. The mouseID byte is always the next byte sent after
the ACK for the Read MouseID command. At initialization, the mouseID is always 0. Other current legal values are
3 and 4.
Line 406 ⟶ 425:
====Init/Detection Command Sequences====
If you would like more than just 3 buttons, you will have to use the following sequence(s).
If the first sequence is accepted: the number of bytes in the mouse packets changes to 4, the scroll wheel on the
if a sequence is accepted, then the number of packets change ( see Format of First 3 Packet Bytes, and the Format of the optional 4 Packet Bytes), also notic the mouse ID changes if the sequence is accepted. So if the sequence is not accepted, the ID remains, if accpeted it change.
mouse becomes activated, and the mouseID changes from 0 to 3.
 
The first magic sequence goes like this:
* set sample rate to 200
* set sample rate to 100
* set sample rate to 80
* get the new id to verify acceptance
<br>
this will only activate the scroll wheel
 
<b>After using the above sequence to activate the scroll wheel</b>, the 4th and 5th mouse buttons can be activated
 
with the following additional magic sequence:
* set sample to 200
* set sample rate to 200
* set sample rate to 80200
* set sample rate to 80
* get the id
* get the new id to verify acceptance
<br>
If this second sequence is accepted, the returned mouse ID value changes from 3 to 4.
this will activate the scroll wheel, and the 4th and 5th button.
 
in order to try the second, you will need to do the first, you can not just skip the first.
 
====Enable Packets====
After the mouse has been initialized to theyour correctdesired mouseID value, its Samplerate is probably 80 samples per second,
its Resolution is probably 4 pixels/mm, and packets are still disabled. You may want to modify the Samplerate
and Resolution, and then you need to send a 0xF4 command to the mouse, to make the mouse automatically generate movement packets.
 
packets.
====Streaming Advantages and Disadvantages====
Instead of enabling automatic streaming packet mode, it is possible to request mouse packets one at a time. Doing this
has some advantages over streaming packet mode. You may see that you need to send or receive at least 4
extra bytes over the I/O bus in order to get each 0xEB command to the mouse, and the I/O bus is very slow. On the other
hand, a typical streaming mode probably sends hundreds more mouse packet bytes over the I/O bus than you need, every second
-- so if there is a disadvantage, it is probably small.
 
One of the biggest problems with streaming mode is "alignment" -- the packets were never defined to have an obvious boundary.
This means that it is very easy to lose track of which mouse byte is supposed to be the first byte of the next packet.
This problem is completely avoided if you specifically request single packets (instead of using streaming mode) because
every packet begins with an ACK (0xFA), which is easily recognizable.
 
===PC Serial Mouse===
 
For info on running a serial mouse on an RS232 port, see [http://freedos-32.sourceforge.net/showdoc.php?page=sermouse this document from the freedos documentation].
 
==Mac Mouse Interface==
 
{{Stub}}
(stub - to be written later)
 
 
==See Also==
===Threads===
* [http[topic://www.osdev.org/phpBB2/viewtopic.php?t=10247 |SANiK's mouse code]]
* [[topic:24277|Mouse driver code in assembly]]
* [http://www.osdev.org/phpBB2/viewtopic.php?t=8323 PS2 mouse IRQ]
* [http[topic://www.osdev.org/phpBB2/viewtopic.php?t=6942 8323|PS2 mouse linksIRQ]]
* [[topic:6942|PS2 mouse links]]
 
===External Links===
* [http://os-development.000webhostapp.com/mys.html Tutorial on page os-development]
* [http://www.isdaman.com/alsos/hardware/mouse/ps2interface.htm Adam Chapweske's tutorial]
* [https://www.avrfreaks.net/sites/default/files/PS2%20Keyboard.pdf Adam Chapweske on PS/2 Mouse and Keyboard protocols]
* [http://www.computer-engineering.org/index.php?title=PS/2_Mouse_Interface Alternate link to Chapweske's tutorial]
* [http://www.win.tue.nl/~aeb/linux/kbd/scancodes-13.html Linux PS2 mouse article with non-Microsoft mouse info]
* [http://houbysoft.xf.czcom/download/ps2mouse.html Tutorial with sample C code]
* [http://www.computer-engineering.org www.Computer-Engineering.org]
* [http://www.mcamafia.de/pdf/ibm_hitrc07.pdf IBM's Keyboard and Auxiliary Device (mouse) Controller documentation]
 
[[Category:Human Interface Device]]
[[de:PS/2-Maus]]
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