linux-kernel - Re: Help on testing ad5933 driver

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Message-ID: <CA+U=DsoWsWSfyrSneZfoWzXeYjO0u+G0PPtsPQi9ov11w+pcRQ@mail.gmail.com>
Date:   Fri, 22 Mar 2019 22:34:21 +0200
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Marcelo Schmitt <marcelo.schmitt1@...il.com>
Cc:     "Hennerich, Michael" <michael.hennerich@...log.com>,
        stefan.popa@...log.com, alexandru.Ardelean@...log.com,
        dragos.bogdan@...log.com, Jonathan Cameron <jic23@...nel.org>,
        linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        LKML <linux-kernel@...r.kernel.org>, kernel-usp@...glegroups.com
Subject: Re: Help on testing ad5933 driver

On Thu, Mar 21, 2019 at 9:39 PM Marcelo Schmitt
<marcelo.schmitt1@...il.com> wrote:
>
> Hello, would anyone mind helping me test ad5933 driver on actual
> hardware?  I went through this
> (https://oslongjourney.github.io/linux-kernel/experiment-one-iio-dummy/)
> tutorial so I was able to load iio_simple_dummy driver, create and
> inspect some dummy devices.  Now, as Jonathan has asked me, I would like
> to test ad5933 driver on an EVAL-AD5933 board which was donated to FLUSP
> (https://flusp.ime.usp.br/).
>
> So far I've been hesitating to plug this device on my Debian distro
> since this
> (https://www.analog.com/media/en/technical-documentation/user-guides/UG-364.pdf)
> user guide for Windows says not to connect it before driver
> installation. Is there something that could harm the board if plugged
> on a computer without a proper driver?
>

You should take into account that a lot of eval boards have their eval
SW written for Windows.
This is something of a legacy-thing, because most corporations have
been running their computers (for work & dev & offices) on Windows.

So, you shouldn't take things ad-literam (to the letter) when reading
stuff for Windows and when writing code for Linux.

> I also didn't understand the hardware configuration showed on this
> (https://wiki.analog.com/resources/tools-software/linux-drivers/iio-impedance-analyzer/ad5933)
> page.

Hmm, that doc was written a while ago.
The newer eval board doesn't look like the one in the wiki.

Also, since the eval SW was targeted for Windows, getting it to work
for Linux (and IIO) implies some hacking/reverse-engineering.
The reason for this (reverse-engineering) is because [traditionally]
eval boards are meant to highlight characteristics of the chip, so if
using Windows, this should be simple.

Unfortunately, the docs aren't helping in this case. So, in this case,
I would get some volt-meter & oscilloscope to help.
It looks to me that U2 is the AD5933 on the eval-board.
Worst case, you can solder directly to the pins and link them to a
Raspberry PI [on the I2C], power, ground, etc.
But, you can take a look at the T1 to T8 (if I didn't miss anything)
and connect to them, and see what each of them is for.
Hopefully, one of those test-points is for I2C, in which case you can
attach wires to them and connect them to a host.
I did not find a good doc for them yet.

But anyway, I would ask some HW guy to help here (because I'm a SW guy
mostly),and get help on figuring out the eval board

>
> Any advice will be greatly appreciated.
> Thanks in advance,
>
> Marcelo