HAA Infra Red
Since version 1.5.0 HAA has been able to control infra-red (IR) devices. In order to do this the HAA accessory must have an infra-red transmitter.
Examples of devices that have infra-red transmitters are:
Alternatively look at some examples on the Web of how to add an IR transmitter to an accessory.
To understand more about infra-red transmissions and how they are used to control devices around the home refer to the following sites for more information:
All IR commands consist of groups of infra-red light pulses sent sequentially.
These pulses are split into marks and spaces. With marks being the period
where infra-red light is transmitted and spaces being the period where no
infra-red light is transmitted.
A mark consists of an alternating burst of infra-red light where the
light is pulsed on & off at a particular frequency.
The most common frequency used by IR transmitters is 38KHz.
Manufacturers often define an IR protocol for their equipment.
This protocol defines the duration of marks & spaces as well as the commands
that can be sent and what those commands mean.
Sony TV remotes use the Sony Control-S protocol for instance.
For more details on IR data formats checkout this
Vishay document or this
IR Remote Control Theory
document.
HAA supports IR control by enabling the specification of either RAW
or Protocol formats for the data to be transmitted.
A RAW format defines the code to send as an exact replica of a captured signal.
HAA Setup mode is provided for enabling the capture of remote control codes using an IR
receiver hooked up to an HAA accessory.
A Protocol format defines the infra-red sequence exactly how the manufacturer
intended the codes to be sent.
HAA IR/RF Capture Tool, available into HAA Setup Mode.
In RAW mode the IR codes are sent exactly as captured using the HAA IR/RF Capture Tool.
Transmitting the raw captured data is not recommended because you are using a
copy of the signal and the quality of the captured signal may be degraded. Use
it only if you are unable to decipher the protocol being used by the equipment.
RAW mode also uses a lot more flash storage to hold the definition of the
codes, requiring 2 characters for each mark or space sequence.
Below is a sample output from using the tool.
The table shows the sequential codes that have been captured by the tool.
In order to re-transmit these codes using RAW mode the numeric values need to
be translated into a RAW code string.
This can be done using the IR Encoder Table.
From the table you can convert the integer code stream into a series of HAA
RAW codes.
Round the integers output by the tool to the nearest 0 or 5 and
then find this value in the N column of the IR Encoder Table.
The corresponding value in the C column can then be used to create a RAW
code sequence to be transmitted by your HAA accessory.
In the above table the RAW code string can be constructed as follows:
- The integer
3550is represented by the codeHt - The integer
1677, rounded down to1675, is represented by the codeDC - The integer
500is represented by the codeAQ - The integer
362, rounded down to- 360is represented by the code0=etc...
The RAW code string can then be constructed as
"w" : "HtDCAQ0=A5B>AP0=AR0=AR0=AR0=AR0=AR0=AR0=AR0?AR0A50=AR0ARCDAK0=AR0=AR0=AR0=AR0=AR0=AR0?AR0?AR0=ARB>AQ0=A50=AR0=AR0-AK0-AL0=AR0=AR0=AR0>AP0?ARCDAKB>APB>APB>AP0=AR0=ARB>AP0?ARCDAKCDAKC0APB>AP0?ARCDAK"
Note: see how long the string becomes when using RAW codes!
In Protocol mode the format and sequence is defined as a fixed pattern
consisting of a header, the data and a footer.
Almost all IR receivers for devices support defined protocols.
Unfortunately different manufacturers have different protocols.
There is no single IR protocol that is able to control all IR enabled devices.
Using the HAA IR/RF Capture Tool, accessible from Setup Mode,
it is possible to capture an IR sequence and decode that sequence into an IR protocol.
Once the protocol has been defined it is then possible to encode IR commands in
much shorter data strings than trying to re-transmit a RAW code sequence.
In HAA the Protocol is defined as having four fields:
-
Header: the first mark (+), space (-) sequence -
Bit 0: a mark (+), space (-) sequence defining a bit 0 value -
Bit 1: a mark (+), space (-) sequence defining a bit 1 value -
Footer: the last mark (+) transmitted in the sequence
To define the Protocol the captured RAW sequence must be analysed and decoded.
The captured code sequence below consists of a press of the power on/off button
from a Panasonic TV remote.
In this captured sequence the four fields are colour coded as Header, Bit 0, Bit 1, Footer
Breaking down the code sequence and using the IR Encoder Table
we start with the Header.
This has a mark (+) value of 3550, translated to Ht and a space (-) value
of 1677, rounded to 1675 and translated to DC.
Examining the Bit 0 values.
Marks are in the range 490 to 510, so we can use a value of 500, translated to AQ.
Spaces are in the range 360 to 365, so we use a value of 365, translated to 0?
Examining the Bit 1 values.
Marks are in the range 490 to 510, so we can use a value of 500, translated to AQ.
Spaces are in the range 1240 to 1260, so we use a value of 1250, translated to CA
Finally, we can see the Footer value of 473,
rounded to the value of 470 and translated to AK.
Referring to the details within the IR Action
definition we need to combine the results of the above into a Protocol string "p".
This is done using the format: "p": "HHHH00001111FF" where
| Field | Description |
|---|---|
| HHHH | Header mark & space |
| 0000 | Bit 0 mark & space |
| 1111 | Bit 1 mark & space |
| FF | Footer mark |
Resulting in a Protocol definition of "p": "HtDCAQ0?AQCAAK".
Defining the pattern for all IR commands that can be used to control the Panasonic TV.
All IR commands will be sent using a defined IR protocol.
Within HAA the default protocol can be set in the General Configuration
section of the device setup, but can be overridden at any time by adding a
protocol "p" key within an Accessory (in this case, protocol will be used
for all IR Actions inside accessory), or even within an IR Action.
Continuing with our captured data from above we can decode the IR command by analysing the sequence of Bit 0 and Bit 1 patterns then use the IR Protocol Multiplier Table to translate the number of times each bit must be sent into an IR command code.
The captured IR sequence shows a single Bit 0
(a), followed by a single Bit 1 (A),
followed by 11 Bit 0s (k), then a single
Bit 1 (A) etc.
The resultant IR command within the IR Action
becomes "c" : "aAkAiAhAaDbAaDaA"
Using the technique above any IR device can be captured and translated into
an HAA IR Protocol and set of IR commands.