Luke,
Have you considered using the Audio Return channel in HDMI v1.4 to send digital multi-channel sound back to the EOMA68-A20? How about the Ethernet channel (also in HDMI v1.4)?
Does the processor support these? They are optional capabilities of HDMI v1.4 and I only ask because it would change the routing.
Sincerely, Richard
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Tue, Aug 1, 2017 at 5:53 AM, Richard Wilbur richard.wilbur@gmail.com wrote:
Luke,
Have you considered using the Audio Return channel in HDMI v1.4 to send digital multi-channel sound back to the EOMA68-A20? How about the Ethernet channel (also in HDMI v1.4)?
CEC etc i believe is supported i can't remember the details, it's covered by the processor and is somewhere in the datasheet. certainly i know there's an hdmi audio kernel module for sound playback in the sunxi-3.4 kernel.
so *i'm* not quotes considering it quotes - if it's there and there's a linux kernel module it's there, people can compile it and use it.
l.
On Mon, Jul 31, 2017 at 11:13 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
CEC etc i believe is supported i can't remember the details, it's covered by the processor and is somewhere in the datasheet. certainly i know there's an hdmi audio kernel module for sound playback in the sunxi-3.4 kernel.
Sorry, I explain things well enough. Sound playback normally refers to sound output from the kernel to D/A, amplifier, and speakers. Same direction as video playback: from computer to monitor.
CEC: Consumer Electronics Control Allows devices to pass control information around. Say you have a remote control for your television that has "Play" and "Pause" buttons on it, for instance. Through CEC the commands could be sent from your television to the EOMA68-A20 card via the HDMI cable and software there could respond appropriately to the events.
ARC: Audio Return Channel The Audio Return Channel supports sending digital multi-channel sound upstream (for input to the computer). This would allow recording, mixing, special effects, etc.
so *i'm* not quotes considering it quotes - if it's there and there's a linux kernel module it's there, people can compile it and use it.
From the sound of things, CEC was there from the beginning and ARC is
new in v1.4 but doesn't require circuit changes on the HDMI transmitter PCB to accommodate. ARC does require support in the HDMI block/subsystem of the SoC.
On the other hand, if we plan to support HEC (HDMI Ethernet Channel) it requires us to route one more pair of signals as a differential pair.
On Tue, Aug 1, 2017 at 6:44 AM, Richard Wilbur richard.wilbur@gmail.com wrote:
On the other hand, if we plan to support HEC (HDMI Ethernet Channel) it requires us to route one more pair of signals as a differential pair.
the micro-hdmi connector's pins are entirely packed out. i know that there's no extra pins available (there's only 19, 1 of them unused), and there are definitely no extra pads coming out from the A20 which could be identified as HEC.
l.
I forgot to cite some sources:
Audio Return channel[1] Claims to be able to carry the signals normally routed over an S/PDIF cable from the video signal receiver (sink) back to the video signal transmitter (source).
Ethernet channel[2] Offers up to 100Mb/s bandwidth networking.
HDMI Specification Availability: "HDMI Specification Ver.1.4b and the Compliance Test Specification Ver.1.4b (CTS 1.4b), released on October 11, 2011, are available for download only by Licensed HDMI Adopters." [3]
"The HDMI Specification Ver. 1.3a is available at no charge. To download this version of the HDMI specification, please complete the form that follows.
The HDMI Specification Ver. 1.4a is available to HDMI Adopters via the Adopter extranet. Adopters can click here to log into the Adopter Extranet."
Adopter Registration: "Licensing Option
Please select which HDMI Adopter agreement is appropriate for your company.
Manufacturers of End Products that will include HDMI:
Ten thousand fixed annual licensing fee plus royalty Five thousand annual licensing fee plus $1.00 administration fee per licensed product plus royalty"
I'd love to download the specification but they have it behind a signed agreement + steep pay wall.
References:
[1] http://www.hdmi.org/manufacturer/hdmi_1_4/arc.aspx [2] http://www.hdmi.org/manufacturer/hdmi_1_4/hec.aspx [3] http://www.hdmi.org/manufacturer/specification.aspx [4] http://www.hdmi.org/manufacturer/adopter_registration.aspx
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Tue, Aug 1, 2017 at 6:21 AM, Richard Wilbur richard.wilbur@gmail.com wrote:
Audio Return channel[1] Claims to be able to carry the signals normally routed over an S/PDIF cable from the video signal receiver (sink) back to the video signal transmitter (source).
yes. there exists a kernel module. absolutely no information is available about how it works.... except as can be read in the source code.
I'd love to download the specification but they have it behind a signed agreement + steep pay wall.
yyeah.. not hugely gonna worry about it. if it works it works, if it doesn't it doesn't.
l.
arm-netbook@lists.phcomp.co.uk
-
Luke Kenneth Casson Leighton -
Richard Wilbur