[AudioI] Audio Injector Isolated GPIO Pin Use

[Jonathan]

Hi All,

I did some more investigation. It looks like the UART TX and RX pins on the
Audio Injector Isolated are not connected to anything and do not connect to
the passthrough header.

Pin 11 on the Pi header, GPIO17 connects to one input of an AND gate and
the output connects to GPIO17 on the GPIO header. The other input of the
AND gate connects to a digital isolation IC and to the LMUTE pin of the
output header. On the RCA breakout board, LMUTE doesn't seem to be
connected to anything, but I'm not sure on that. With black solder mask,
the traces are hard to see. If it is floating, a HIGH should make it to
that input of the AND gate and a HIGH should make it to the output.

Pin 7 in the Pi header, GPIO4, directly connects to GPIO4 on the GPIO
header.

Matt,

Am I correct with this? I'd like to use GPIO17 and GPIO4 in my application,
as well as have the UART TX and RX on the passthrough header. Here is the
schematic I drew up:


Thanks.

Jonathan



On 9/25/21, Jonathan <emuman100 at gmail.com> wrote:

> Hello All,

>

> I did some investigation and it looks like one of the GPIO pins that is

> utilized is GPIO17 to trigger the muting relay on the audio output on the

> RCA breakout board.

>

> For my application, I will only be utilizing the audio input, so

> functionality of output muting isn't really needed. The issue is that I

> already utilize GPIO17. I can easily unsolder the GPIO pin header on the

> RCA breakout, but how can I free up GPIO17 in Raspbian then when I enable

> the driver?

>

> Also, are there any other GPIOs that might be utilized on the Audio

> Injector Isolated? I utilize GPIO4, 17, 24, 27, and the console port in my

> application.

>

> Thank you.

>

> Jonathan

>

>

>

>

> On 9/23/21, Jonathan <emuman100 at gmail.com> wrote:

>

>> Hello,

>

>>

>

>> Does the Audio Injector Isolated make use of any GPIO pins on the Pi

>

>> other than the I2C and I2S lines? If so, which ones does it use?

>

>>

>

>> Also, can I simply solder a header to the unpopulated passthrough

>

>> header and have direct access to the GPIO pins? I use a total of 4

>

>> GPIO pins in my project.

>

>>

>

>> Thanks.

>

>>

>

>> Jonathan

>

>>

>
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