Any brave dive computer download testers out there?
jef at libdivecomputer.org
Thu Apr 19 01:20:54 PDT 2018
On 2018-04-19 09:42, Sébastien Dugué wrote:
> On Thu, Apr 19, 2018 at 1:50 AM, Linus Torvalds
> <torvalds at linux-foundation.org> wrote:
>> On Wed, Apr 18, 2018 at 4:18 PM, Linus Torvalds
>> <torvalds at linux-foundation.org> wrote:
>>> 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.
>> Hmm. Googling around, I see that it might also be the Sigmatel
>> Stir4200 (USB ID 066F:4210).
>> That actually has better documentation, and shows exactly the framing
>> for the normal MIR format (which it would be for the normal 9600
>> baud). I suspect the MCS7780 needs that same format, it's just not
>> documented as well.
>> The packet wrapping looks like this:
>> 0x55 0xaa 2-byte LE length, 0xC0*n .. escaped data .. 2-byte LE
>> CRC 0xc1
>> and from what I can tell, the Stir4200 also resets to sane default
>> values (9600 baud SIR).
>> But you may have to do some USB control transfers to set the data
>> direction. It *looks* like the MCS7780 is simpler and defaults to just
>> "automatic data direction" (which presumably just means "send if there
>> is TX data, receive otherwise").
> Yes, but to me talking to the chip is the easy part. I'm more
> about implementing enough of the irda protocol stack to be able to talk
> to all those embedded stacks.
I discovered this a while ago:
It seems to be based on some minimal IrDA stack for micro-controllers:
This is probably a good starting point!
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