Date: Wed, 26 Oct 2016 17:37:11 -0700 From: Russell Haley <russ.haley@gmail.com> To: Koz Ross <koz.ross@retro-freedom.nz> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: BeagleBone Black - what still needs to be done for audio? Message-ID: <CABx9NuTk05jQ00HzFi2GHBAWpDaKtVaFRy-a%2BuNfCaribzyKrQ@mail.gmail.com> In-Reply-To: <CABx9NuSwFQtHQtiua_fGdCbYwv%2B4RCYD0qBEAWZR9QwMHZCjyQ@mail.gmail.com> References: <20161026091428.GA1468@Sebastian> <CABx9NuSRrvnvrT4CRvUOgGDVf3bwfBJ-BmHi7EJq9FEEx9Xy8A@mail.gmail.com> <CABx9NuSwFQtHQtiua_fGdCbYwv%2B4RCYD0qBEAWZR9QwMHZCjyQ@mail.gmail.com>
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On Wed, Oct 26, 2016 at 4:27 PM, Russell Haley <russ.haley@gmail.com> wrote: > On Wed, Oct 26, 2016 at 9:28 AM, Russell Haley <russ.haley@gmail.com> wrote: >> On Wed, Oct 26, 2016 at 2:14 AM, Koz Ross <koz.ross@retro-freedom.nz> wrote: >>> I've been meaning to get into both ARM and BSD for a while, so I decided I >>> would begin with FreeBSD and a BeagleBone Black I have lying around. I read >>> this page: https://wiki.freebsd.org/FreeBSD/arm/BeagleBoneBlack , which >>> states >>> that audio on the BBB 'still needs to be done'. >>> >>> I was wondering what it means by 'still needs to be done', and what >>> precisely >>> needs to be done to have working BBB audio. As I am very new to both ARM and >>> BSD, could someone please fill me in? I would like to contribute if I can. >> >> >> That page is a little out of date, but I don't have a recent image for >> my BBB. Have you tried running the latest image? If I remember >> correctly: >> >> https://www.freebsd.org/where.html -> download the sd card image. >> >> xzcat <download-dir>/FreeBSD-11.0-RELEASE-arm-armv6-BEAGLEBONE.img.xz >> | dd of=/dev/da<yer-sd-card> bs=1m (or is it bs=1M?) >> >> The FreeBSD handbook is the place to start at. It will give you >> directions on how to get your image set up: >> >> https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/ >> >> Once you're able to setup and test HDMI and have a running image, >> you'll be in a better position to start looking at audio issues. >> >> Do you know anything about the BBB hardware? You'll need to find out >> what the audio interface is and if the FreeBSD kernel supports it. >> Then you need to find out if it's in the default kernel, if not, >> you'll need to learn to build the kernel yourself (or build the module >> and install and load it). > > I'm bored of Javascript at work... This looks like a good lead for you: > > https://www.element14.com/community/community/designcenter/single-board-computers/next-gen_beaglebone/blog/2013/05/28/bbb--audio-notes Last post, I promise (with fingers crossed) and then I'll go home. Talking to a hardware engineer, his general outline was this: - I2S is a specific driver to output audio. It will typically be fed into a hardware codec chip. That jives with the previous link I sent. "The nice thing about the latter is what it derives the audio from; a hardware I2S interface inside the AM3359, which sends data out to an NXP TDA19988 for conversion to HDMI." - The codec chip will need to be supported by the OS and is typically set up using an I2C (Not I2S!)bus to set various configurations: mono/stero/multichannel, data rates, output frequencies and the like. So: - What is the state of I2S for Arm on FreeBSD (specifically for the TI AM3358)? I don't know. - What is the state of the support for NXP TDA19988? Well it seems to do video but not audio. BBB Hardware schematic: https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SCH.pdf?raw=true -->See Page 10 of 11 for the schematics. http://datasheet.octopart.com/TDA19988BHN-C1%2C551-NXP-Semiconductors-datasheet-67049582.pdf --> General datasheet with a nice simple picture of the inputs and outputs. >From those two diagrams one could surmize that pins AP0, AP1 and ACLK are input from the I2S bus. Finally, here is the driver set for the TI chips: https://svnweb.freebsd.org/base/head/sys/arm/ti/am335x/ I saw some HDMI stuff in am335x_lcd.c but didn't get any further than that. Good Luck! Russ
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