MIME-Version: 1.0
In-Reply-To: <ef4e8b01-c6c2-6456-1e5d-6daddc963302@abelian.org>
References: <ef4e8b01-c6c2-6456-1e5d-6daddc963302@abelian.org>
From: Andy Talbot <andy.g4jnt@gmail.com>
Date: Tue, 14 Feb 2017 16:03:28 +0000
Message-ID: <CAA8k23RC4oz=+gmqwma-7cV2FYS9HdxWic67xszsfCkB8y--hw@mail.gmail.com>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Raspberry Pi sound interface that works
Content-Type: multipart/alternative; boundary=94eb2c0b26b869423805487fb404
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: RO

--94eb2c0b26b869423805487fb404
Content-Type: text/plain; charset=UTF-8

Is it any more than a CODEC chip?

They use SPI or similar  and  DSP chips have custom interfaces to make the
most of them.    So the RPi wit its fast serial interface should cope with
most CODECs.   Someone just has to write the code ;-)

Andy  G4JNT

On 14 February 2017 at 15:52, Paul Nicholson <vlf0403@abelian.org> wrote:

>
> USB audio on the Raspberry Pi is pretty useless thanks to
> lost USB packets.   A much better solution for audio is to
> use the I2S bus via add-on boards such as the Wolfson.
>
> Unfortunately the Wolfson never worked with the quad core RPi.
> I'm just testing another one, called an Audio Injector from
> Flatmax Studios.  It uses the same wm8731 chip as the Wolfson
> but works with the quad core Pi:
>
>  http://audioinjector.net/
>  https://www.amazon.co.uk/gp/product/B01HBC8CJ0/
>
> Runs up to 96k samples/sec stereo in full duplex.
>
> Measured input performance is at
>
>  http://abelian.org/scard
>
> (Ignore the two spikes in the noise floor, these are from
> the neighbour's solar panel. I'll measure the noise again
> after sunset!)
>
> Noise is lower than 1uV in 1Hz and full scale input is
> quite high, so the dynamic range is great.  It runs at
> 32 bits per sample very nicely.
>
> It appears to run real well with ebsynth:
>
>  http://abelian.org/vlf/tmp/170214b.gif
>
> Uses about 11% of one core and appears as good if not better
> than even a PCI soundcard on a PC!
>
> It looks like Flatmax Studios are kick starting development
> of a multi-channel version with 8 outputs and 6 inputs. If
> that works it will be great for 3 axis coherent reception
> with just one Raspberry Pi.  Due apparently in April.
>
> A lot more testing to do but so far it looks promising.
> Sorry I just bought the last two from Amazon uk so they're
> out of stock for the moment!
> --
> Paul Nicholson
> --
>
>
>

--94eb2c0b26b869423805487fb404
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Is it any more than a CODEC chip?<div><br></div><div>They =
use SPI or similar =C2=A0and =C2=A0DSP chips have custom interfaces to make=
 the most of them. =C2=A0 =C2=A0So the RPi wit its fast serial interface sh=
ould cope with most CODECs. =C2=A0 Someone just has to write the code ;-)</=
div><div><br></div><div>Andy =C2=A0G4JNT</div><div class=3D"gmail_extra"><b=
r><div class=3D"gmail_quote">On 14 February 2017 at 15:52, Paul Nicholson <=
span dir=3D"ltr">&lt;<a href=3D"mailto:vlf0403@abelian.org" target=3D"_blan=
k">vlf0403@abelian.org</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_=
quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1=
ex"><br>
USB audio on the Raspberry Pi is pretty useless thanks to<br>
lost USB packets.=C2=A0 =C2=A0A much better solution for audio is to<br>
use the I2S bus via add-on boards such as the Wolfson.<br>
<br>
Unfortunately the Wolfson never worked with the quad core RPi.<br>
I&#39;m just testing another one, called an Audio Injector from<br>
Flatmax Studios.=C2=A0 It uses the same wm8731 chip as the Wolfson<br>
but works with the quad core Pi:<br>
<br>
=C2=A0<a href=3D"http://audioinjector.net/" rel=3D"noreferrer" target=3D"_b=
lank">http://audioinjector.net/</a><br>
=C2=A0<a href=3D"https://www.amazon.co.uk/gp/product/B01HBC8CJ0/" rel=3D"no=
referrer" target=3D"_blank">https://www.amazon.co.uk/gp/p<wbr>roduct/B01HBC=
8CJ0/</a><br>
<br>
Runs up to 96k samples/sec stereo in full duplex.<br>
<br>
Measured input performance is at<br>
<br>
=C2=A0<a href=3D"http://abelian.org/scard" rel=3D"noreferrer" target=3D"_bl=
ank">http://abelian.org/scard</a><br>
<br>
(Ignore the two spikes in the noise floor, these are from<br>
the neighbour&#39;s solar panel. I&#39;ll measure the noise again<br>
after sunset!)<br>
<br>
Noise is lower than 1uV in 1Hz and full scale input is<br>
quite high, so the dynamic range is great.=C2=A0 It runs at<br>
32 bits per sample very nicely.<br>
<br>
It appears to run real well with ebsynth:<br>
<br>
=C2=A0<a href=3D"http://abelian.org/vlf/tmp/170214b.gif" rel=3D"noreferrer"=
 target=3D"_blank">http://abelian.org/vlf/tmp/17<wbr>0214b.gif</a><br>
<br>
Uses about 11% of one core and appears as good if not better<br>
than even a PCI soundcard on a PC!<br>
<br>
It looks like Flatmax Studios are kick starting development<br>
of a multi-channel version with 8 outputs and 6 inputs. If<br>
that works it will be great for 3 axis coherent reception<br>
with just one Raspberry Pi.=C2=A0 Due apparently in April.<br>
<br>
A lot more testing to do but so far it looks promising.<br>
Sorry I just bought the last two from Amazon uk so they&#39;re<br>
out of stock for the moment!<br>
--<br>
Paul Nicholson<br>
--<br>
<br>
<br>
</blockquote></div><br></div></div>

--94eb2c0b26b869423805487fb404--