Linux input module to use Microsoft® Remote Keyboard for Windows XP® Media Center Edition and the matching receiver as a keyboard and mouse replacement.
Technical Background
The data from the keyboard is transferred via infrared (IR) light. Therefore the infrared light is pulsed at a high frequency (usually round about 35 kHz). The receiver takes notice of that light and measures the time, it is received. It also measures the time, it does not receive infrared light. In this case, the digital information is encapsulated in the relation between on- and off-times.IR timing parameters used
RC6 - Media Keys
First, a synchronisation pulse of 2600µs to 3300µs is sent. Following that pulse, pulses and spaces of either 350µs to 600µs, 750µs to 1000µs or 1200µs to 1600µs are used. Each of these possible length is given a logical length of 1, 2 or 3. The sync has a logical length of 6. With this information, a series of zeroes (for spaces) and ones (for pulses) can be built. Due to limitations of the receiver used, the final space is missing and should be substituded. Here is an example of the green start key pressed:111111 00 10 10 10 01 0011 10 01 01 01 01 01 01 01 01 01 01 01 10 10 10 10 01 01 01 01 01 10 01 01 01 01 01 01 10 10 01 10A combination of two states gives us the final digital data. Whenever a combination 01 is seen, it results in a 0; 10 results in 1. All other pairs are not allowed. Be aware of the header consisting of the sync pulse (length 6), a space of length 2 and four bits followed by the so called 'toggle bit' -- in this case consisting of 0011 (i.e. double length). The four bits in header do not carry important information for this case. They can be used to identify the data packet, since possibly other remote controls use this kind of code, which could lead into confusion.
The final decoding of our above mentioned packet (omiting the section from sync to toggle) gives us:
1000 0000 0000 1111 0000 0100
0000 1101
The most significant bit (MSB) comes first. See below for information
on the content
of those data packets.
RC5 - Keyboard and Mouse
Basically the same technique as for the media keys is used. We have a sync pulse of 2600µs to 3300µs and pulse lengths of 150µs to 450µs or 500µs to 750µs, which are somewhat faster than for the media keys. Here, no toggle bits or long spaces are used. Beside the content, the data for mouse and keyboard differ in length. Some information shows up the possibility that a japanese keyboard exists with different timing.Data Payload
The information presented here is mostly derived from recording IR data and is incomplete and highly subjective.
Media Keys
The layout is as follows| Identification |
C |
Code Set |
Identification |
Pressed
Button |
||||
|---|---|---|---|---|---|---|---|---|
| 1000 |
0000 |
0000 |
1111 |
x |
xxx |
0100 |
xxxx |
xxxx |
The meaning of 'Code Set' is not known to me and is always 000 for the key strokes mentioned here. The bit 'C' seems to vary from keyboard to remote control and is not clear to me.
| Value |
Pressed Button |
|---|---|
| 0x00 |
0 (rc only) |
| 0x01 |
1 (rc only) |
| 0x02 |
2 (rc only) |
| 0x03 |
3 (rc only) |
| 0x04 |
4 (rc only) |
| 0x05 |
5 (rc only) |
| 0x06 |
6 (rc only) |
| 0x07 |
7 (rc only) |
| 0x08 |
8 (rc only) |
| 0x09 |
9 (rc only) |
| 0x0A |
Delete (rc only) |
| 0x0B |
Enter (rc only) |
| 0x0C |
PC Power |
| 0x0D |
Green Logo Button |
| 0x0E |
Mute |
| 0x0F |
Info |
| 0x10 |
Vol + |
| 0x11 |
Vol - |
| 0x12 |
Ch/Pg + |
| 0x13 |
Ch/Pg - |
| 0x14 |
Fwd |
| 0x15 |
Rew |
| 0x16 |
Play |
| 0x17 |
Record |
| 0x18 |
Pause |
| 0x19 |
Stop |
| 0x1A |
Skip |
| 0x1B |
Replay |
| 0x1C |
# (rc only) |
| 0x1D |
* (rc only) |
| 0x1E |
Up |
| 0x1F |
Down |
| 0x20 |
Left |
| 0x21 |
Right |
| 0x22 |
OK |
| 0x23 |
Back |
| 0x24 |
DVD Menu |
| 0x25 |
Live TV |
| 0x26 |
EPG |
| 0x46 |
TV (keyboard only) |
| 0x47 |
Music (keyboard only) |
| 0x48 |
Recorded TV |
| 0x49 |
Pictures (keyboard only) |
| 0x4A |
Videos (keyboard only) |
| 0x50 |
Radio (keyboard only) |
| 0x5A |
Videotext (rc only) |
| 0x5B |
Red (rc only) |
| 0x5C |
Green (rc only) |
| 0x5D |
Yellow (rc only) |
| 0x5E |
Blue (rc only) |
| 0x64 |
Messenger (keyboard only) |
Mouse
The data layout is as follows:| Identification |
unknown |
ΔY |
ΔX |
R |
L |
Checksum |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 |
0001 |
xxxx |
xxxx |
xxx |
xxxx |
xxx |
xxxx |
x |
x |
x |
xxxx |
The unknown bits also contain a 'code set'. The algorithm used for the checksum is not clear to me.
R is the right button flag, L is the left button flag:
| Bit |
Meaning |
|---|---|
| 0 |
not pressed |
| 1 |
pressed |
The differences in X- and Y-direction are expressed as 7-bit signed integers in two's complement. I have not seen values less than -30 or values greater than +30. Positive X-values indicate movement to the right, positive Y-values indicate movement to the top. For completeness here the full value table (assuming the limit mentioned):
| Value |
Meaning |
|---|---|
| 0x00 |
0 |
| 0x01 |
1 |
| 0x02 |
2 |
| 0x03 |
3 |
| 0x04 |
4 |
| 0x05 |
5 |
| 0x06 |
6 |
| 0x07 |
7 |
| 0x08 |
8 |
| 0x09 |
9 |
| 0x0A |
10 |
| 0x0B |
11 |
| 0x0C |
12 |
| 0x0D |
13 |
| 0x0E |
14 |
| 0x0F |
15 |
| 0x10 |
16 |
| 0x11 |
17 |
| 0x12 |
18 |
| 0x13 |
19 |
| 0x14 |
20 |
| 0x15 |
21 |
| 0x16 |
22 |
| 0x17 |
23 |
| 0x18 |
24 |
| 0x19 |
25 |
| 0x1A |
26 |
| 0x1B |
27 |
| 0x1C |
28 |
| 0x1D |
29 |
| 0x1E |
30 |
| ... |
|
| 0x62 |
-30 |
| 0x63 |
-29 |
| 0x64 |
-28 |
| 0x65 |
-27 |
| 0x66 |
-26 |
| 0x67 |
-25 |
| 0x68 |
-24 |
| 0x69 |
-23 |
| 0x6A |
-22 |
| 0x6B |
-21 |
| 0x6C |
-20 |
| 0x6D |
-19 |
| 0x6E |
-18 |
| 0x6F |
-17 |
| 0x70 |
-16 |
| 0x71 |
-15 |
| 0x72 |
-14 |
| 0x73 |
-13 |
| 0x74 |
-12 |
| 0x75 |
-11 |
| 0x76 |
-10 |
| 0x77 |
-9 |
| 0x78 |
-8 |
| 0x79 |
-7 |
| 0x7A |
-6 |
| 0x7B |
-5 |
| 0x7C |
-4 |
| 0x7D |
-3 |
| 0x7E |
-2 |
| 0x7F |
-1 |
Keyboard
The data layout is as follows:| Identification |
unknown |
Code Set |
unknown |
Key Code |
Shift
Mask |
|||||
|---|---|---|---|---|---|---|---|---|---|---|
| 0 |
0100 |
xxx |
x |
xxxx |
xxxx |
xxxx |
xxxx |
xxxx |
xxxx |
xxxx |
As in the other codes, the 'Code Set' is unknown to me.
The shift mask uses basically bits used also in USB HID. The following table shows the contents of 'Shift Mask'.
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
|---|---|---|---|---|---|---|---|---|
| Key |
Right Logo (n/a) |
Right Alt |
Right Shift |
Right Ctrl |
Left Logo |
Left Alt |
Left Shift |
Left Ctrl |
| Matching Key Code |
0xE7 |
0xE6 |
0xE5 |
0xE4 |
0xE3 |
0xE2 |
0xE1 |
0xE0 |
The right logo key is not existing on my keyboard. The bit is described only for completeness. This bit field enables the keyboard to also send key combinations like Ctrl + Alt + Delete, where Ctrl and Alt is stuffed into the shift mask.
The Key Codes also follow the USB HID standard and are described here only for reference. The assumption is made, that the keyboard is a US English keyboard (which mine is not). The keys have to be translated to your local character set. It is possible that some key codes are not sent by all keyboards, as well as some might be sent, which are not in this table.
| Keycode |
Meaning |
|---|---|
| 0x00 |
All keys released (except those
in Shift Mask) |
| 0x04 |
A |
| 0x05 |
B |
| 0x06 |
C |
| 0x07 |
D |
| 0x08 |
E |
| 0x09 |
F |
| 0x0A |
G |
| 0x0B |
H |
| 0x0C |
I |
| 0x0D |
J |
| 0x0E |
K |
| 0x0F |
L |
| 0x10 |
M |
| 0x11 |
N |
| 0x12 |
O |
| 0x13 |
P |
| 0x14 |
Q |
| 0x15 |
R |
| 0x16 |
S |
| 0x17 |
T |
| 0x18 |
U |
| 0x19 |
V |
| 0x1A |
W |
| 0x1B |
X |
| 0x1C |
Y |
| 0x1D |
Z |
| 0x1E |
1 |
| 0x1F |
2 |
| 0x20 |
3 |
| 0x21 |
4 |
| 0x22 |
5 |
| 0x23 |
6 |
| 0x24 |
7 |
| 0x25 |
8 |
| 0x26 |
9 |
| 0x27 |
0 |
| 0x28 |
↵ |
| 0x29 |
Esc |
| 0x2A |
← (backspace) |
| 0x2B |
Tab |
| 0x2C |
Space |
| 0x2D |
- |
| 0x2E |
= |
| 0x2F |
[ |
| 0x30 |
] |
| 0x31 |
\ |
| 0x32 |
Non-US # |
| 0x33 |
; |
| 0x34 |
' |
| 0x35 |
` |
| 0x36 |
, |
| 0x37 |
. |
| 0x38 |
/ |
| 0x39 |
Caps Lock |
| 0x3A |
F1 |
| 0x3B |
F2 |
| 0x3C |
F3 |
| 0x3D |
F4 |
| 0x3E |
F5 |
| 0x3F |
F6 |
| 0x40 |
F7 |
| 0x41 |
F8 |
| 0x42 |
F9 |
| 0x43 |
F10 |
| 0x44 |
F11 |
| 0x45 |
F12 |
| 0x46 |
Print Screen |
| 0x47 |
Scroll Lock |
| 0x48 |
Pause |
| 0x49 |
Insert |
| 0x4A |
Home |
| 0x4B |
Page Up |
| 0x4C |
Delete |
| 0x4D |
End |
| 0x4E |
Page Down |
| 0x4F |
→ |
| 0x50 |
← |
| 0x51 |
↓ |
| 0x52 |
↑ |
| ... |
|
| 0x64 |
Non-US \ |
| 0x65 |
Application (=context menu) |
| ... |
|
Available Source Code
mod_mce
Since
some new input functions are used in this project, please update your
kernel. You have to enable USB and input in your kernel configuration.
Building is done by executing 'make'. mce_lircd
This is a daemon for those without the USB receiver but with a lirc-compatible receiver. This daemon relies on user input to be activated in your kernel.
lirc_mod_mce
Due to popular demand, I quickly assembled this driver which is basically a combination of mod_mce and a lirc module. This driver allows you to use the keyboard/mouse features as well as the remote control features at the same time.lircd.conf
This config file can be used for the media keys. At the moment you can use either lirc or one of mod_mce or mce_lircd. It can be downloaded here.
Since the project is in some early stage, I unfortunately cannot give you more assistance right now.
For further information take a look at the SourceForge files page.