[Cryptech Tech] dev-bridge board

[Peter Stuge]

Pavel Shatov wrote:
>> True - but have you looked at the source code in the workshop project?
>>
>> Of course I know it quite well by now, but it is really not large.
>
> Yes, I've taken a look, but I'm not that competent with USB, I don't
> know how much code a typical USB project should have, so I'm not the
> right person to ask, whether that piece of code is large or small.

The USB specifics aside, just on the aomunt of C code, it's not large.

In the USB part actually some code can be thrown out, because there
is generic infrastructure in the code for multiple device classes
which are irrelevant in this case. (Audio, HID, storage, etc.)


> Given that we need two USB interfaces (one for management, one for
> data), do we need two LPC1343 chips?

That's a good question!

If two separate connectors is a hard requirement then yes.

Any actual product should probably make sure to isolate management
from regular use.

But if alpha is more of a development board / proof-of-concept then
it might be OK not to isolate them there. OTOH that would be a bad
example.

Since USB is structured we have the option to expose two USB
interfaces over one connector - in that case we only need one chip.

The p11 would use one interface, management software would use the other.
Different interfaces can be used simultaneously by different programs.

We might run into complications on Windows with this, but nowhere else.

(Btw, for maximum confusion 'interface' is a very specific thing in USB,
somewhat similar to a TCP port; a device can have several of them.)


Thanks

//Peter