Pulse-Eight traces its roots to XBMC and concentrates on hardware products (such as pre-built XBMC-based HTPCs and HTPC accessories). One of their most attractive products is the USB CEC adapter, aimed at providing PCs with HDMI CEC functionality. While almost all HTPC oriented GPU cards have HDMI outputs, none of them have CEC functionality. There are a number of CEC solutions for PCs, but none of them are as affordable as the Pulse-Eight USB CEC Adapter that we will be talking about.


Before going into the details, let us have a small detour to talk about HDMI's CEC feature.

HDMI CEC - A Primer

CEC stands for Consumer Electronics Control. It is implemented as a single wire bus in the HDMI connector (pin 13). It allows various HDMI-enabled products to connect and communicate with each other. The intent is to enable one remote control to interface with all the A/V components. Before we go into further details, let us get the Wikipedia link out of the way. It provides a very high level view of what CEC can do for the end user, and the various names under which it is advertised by the TV manufacturers. Various message opcodes can be exchanged between the connected systems in order to do device specific actions (like recording on a STB/DVR) or get general information across (like transferring remote control key press details).

In any HDMI setup, the display is considered to be the root, and gets allocated two special tags, a physical address of 0.0.0.0 and a logical address of 0. In any given system, all CEC enabled devices have both physical and logical addresses, while the non-CEC devices have only physical addresses. Physical addresses are taken up based on the position of the device with respect to the root. For example, if an A/V receiver's output is connected to HDMI1 of the TV, it gets the physical address 1.0.0.0. A device connected to the first HDMI input port of the A/V receiver would get the address 1.1.0.0, while one connected to the second HDMI port would get 1.2.0.0. Logical addresses are taken on by the devices depending on their functionality (as mandated by the CEC specifications document). When the HDMI device menu is brought up on the display (On a Sony KDL46EX720, this is achieved by pressing the Sync Menu button), the display sends a broadcast over the CEC wire to all the downstream devices. It then collects the responses arriving over the CEC wire and presents the user with a list of CEC enabled devices. Choosing one of them ensures that future remote key presses are transferred by the TV to that particular address.

If you are interested in learning about the bus protocol and a bit more in-depth overview, I suggest taking a look at QuantumData's excellent CEC whitepaper (PDF). For more details on the various messages which can be exchanged between the devices, the full CEC specifications from the official HDMI documentation may be perused (PDF).

CEC Solutions for HTPCs

CEC is more popular in consumer electronics equipment compared to HTPCs. As of December 2011, none of the video cards with HDMI output support it. The closest we have come to a big vendor officially supporting HDMI CEC is the Intel DH61AG mini-ITX board with its HTPC header, but it still requires a third party board (something that is not available in the market yet). The HTPC header provides a number of useful features such as a recording LED pin and a CEC pin which can be used by third party boards to implement CEC functionality. You can find out more about the DH61AG itself on MissingRemote.

CEC functionality has been an oft-requested feature from home automation solution developers as well. The first step towards getting CEC functionality in PCs involved some hardware mods as described in this link. A few companies built upon this solution and offered plug-and-play gadgets currently priced around $75. RCAware and RainShadow Tech are the players in that price range. Kwikwai's HDMI CEC-Ethernet-USB-Serial bridge is for high end home automation and is appropriately priced around $370. Kwikwai also runs the CEC-O-Matic website, which helps developers in decoding and creating CEC frames for communication. For the general user, it also gives an idea as to what can be achieved in a home automation system using CEC.

Pulse-Eight's solution, coming in at $48 is the cheapest and most recent option to come up. Since Pulse-Eight works closely with XBMC, support for the CEC adapter comes built into XBMC Eden. In the remainder of the review, we will take a look at the USB CEC adapter package, a description of our testbed, and how we went about installing the drivers. Following this, we take a look at how the adapter works in conjunction with XBMC Eden. In the final section, we will see what lies ahead for Pulse-Eight and its CEC initiative.
 

Setup Notes
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  • ganeshts - Thursday, January 26, 2012 - link

    You need to get the wire out and also get the logic to read stuff on the wire / write onto it (this is where the Atmel microcontroller in the box comes into the picture). What is read and written is transferred through the USB port and controlled by libCEC / XBMC Eden built-in code. Reply
  • Malard - Thursday, January 26, 2012 - link

    You are correct you could use our Internal Adapter (when it's released) and tap the CEC wire straight onto it, but the internal adapter relies on 3.3v constant power, which those mainboards supply, again, with enough soldiering you can rig any board to support CEC with the internal adapter, but its time vs reward, and you would be faster to just use the external adapter Reply
  • zilexa - Thursday, January 26, 2012 - link

    Wich case is being used in this setup? I can only see the back in the picture. I am looking for a new case for my new HTPC and this one seems interesting. I am looking for a small one but they have a limited power supply (60-75 watt). Reply
  • ganeshts - Thursday, January 26, 2012 - link

    zilexa, Please look up the specs of the Vision 3D 252B. It is ASRock's custom case and doesn't come with inbuilt PSU (there is a laptop power adapter sized unit delivering the power). Also, the case is pretty small, and I won't advise putting in CPUs of more than 45W TDP in there. Reply
  • Shadowmaster625 - Thursday, January 26, 2012 - link

    I would love to be able to remote control my receiver. But there aint no way I'm paying those kinds of prices. lol. What is wrong with a simple RS232 serial port? It only costs a few bucks for USB to RS232 converter so you are covered even if your pc has no serial port. It is ubiquitous and pretty easy to program. Reply
  • ganeshts - Thursday, January 26, 2012 - link

    That is a DIY solution :) and good luck getting it integrated all into XBMC. This is a OOTB answer to the home theater control issue. Reply
  • Monkeysweat - Thursday, January 26, 2012 - link

    I got a question you might be able to answer,, at home I have a LG TV and a Samsung HTIB that has no HDMI inputs,,,both units are CEC capable but don't work with each other as missmatched brands

    ,, however I can only plug my PC into the TV and the TV is connected to the HTIB by HDMI (receiver output to TV) and by optical cable (output from TV to receiver) - I have anything I play on my TV passthrough by optical output to the stereo as luck would have it, the TV allows DTS passthrough on HDMI

    If i use the CEC adapter from the PC to TV,, would it be able to control the hometheater in a box connected on a different hdmi line?
    Reply
  • Malard - Friday, January 27, 2012 - link

    Yes, they are a unified bus, so long as all the hdmi wires connect via some device or other, be in the receiver or the TV then you will be fine.

    There is also no restriction as to where in the chain you connect the CEC Adapter
    Reply
  • Monkeysweat - Friday, January 27, 2012 - link

    sweeeeeeeeet

    will this be made to work with raspberry pi as well? Kinda funny to buy an adapter that'll cost more than the device running it, but c'est la vie
    Reply
  • Googer - Tuesday, January 31, 2012 - link

    I suspect, It's not going to be long until nVIDIA and AMD both start implementing CEC in to their hardware and drivers. So devices like these may possibly become short lived. Reply

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