[Cryptech Tech] CLI and UARTs

Peter Stuge peter at stuge.se
Tue Aug 16 14:11:57 UTC 2016

Rob Austein wrote:
> * The console (management port) seems to have serious problems using
>   the new UART.  I suspect this is some kind of line speed / buffer
>   overrun problem.

I've seen a similar issue in the past and fixed that some time ago,
but that was in the other direction - USB->UART, while this problem
is in the other direction UART->USB.

The other problem had to do with emptying the USB receive buffer too
early, before sending data out the UART. It was triggered by sending
more than 64 bytes over the UART "at once".

I'm mostly offline at the moment but I'll have a look into this next
week. Thanks a lot for the report! As always - if you can provide a
test case for the USER port that would be great.

>   It is of course possible that this is a hardware quirk in the
>   particular daughterboard I'm playing with, but I doubt it.

No, not likely. I would expect a firmware problem.


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