Any brave dive computer download testers out there?

Linus Torvalds torvalds at linux-foundation.org
Wed Apr 18 16:18:46 PDT 2018


On Wed, Apr 18, 2018 at 12:27 PM, Sébastien Dugué
<sebastien.dugue.subsurface at gmail.com> wrote:
>
>   I looked into this when writing a simulator of my 2G and as far as I
> remember, there's not much of the stack involved when talking to an irda
> DC. All special cases. I may still have the traffic captures laying around

Hmm. Which IRDA chip is it that is in the Uwatec dongle?

Is it perhaps the MosChip MCS7780? You'd know, because then it would
be using USB ID 9710:7780. That seems to be the common case.

You can find datasheets for it by just googling for

    MCS7780 Datasheet type:pdf

and from a quick look, the setup looks pretty simple. It has various
configuration bits, but it looks like the control register defaults to
al the normal bits, so you may not even need to touch it.

For example, it seems to default to 9600 baud, all automatic defaults
for SIR. Maybe I missed some bit, but it basically seems to default to
"ready to simply be used".

So you might be able to just set up plain USB bulk transfers to send
and receive the data. *Maybe* you need some setup, but it's not clear
that you do.

So accessing this thing with libusb looks fairly straightforward, if
you already have packet traces and know what the wrapping is (I think
the MCS7780 just wants to add a 2-byte little-endian packet length to
the data, but then whatever the IRDA address encapsulation etc is I
have no idea).

                      Linus


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