[Arm-netbook] Early UART output vs. housing board discovery
j.neuschaefer at gmx.net
Tue Jan 16 22:34:08 GMT 2018
Thanks for your explanations. That's all I really have to say after that
On Fri, Jan 12, 2018 at 10:29:14AM +0000, Luke Kenneth Casson Leighton wrote:
> > * If the CPU card spontaneously resets without first bringing the
> > housing into a state where it tolerates early debug output
> > (some housings might require such preparation before shutdown).
> exactly. and that is far too complicated. right now there is *zero*
> need - at all - for *any* kind of complexity on the Housings. the
> Micro-Desktop is.... it's just a bunch of connectors. as in, that's
> *all* that's needed.
I wasn't aware housings tend to be *this* simple.
> > Here's a *completely different* and significantly simpler proposal,
> > which also fulfills these goals. You probably won't like it because
> > (a) it takes away a pin from general purpose use, (b) it breaks
> > compatibility [see footnote 1] with current hardware.
> > Replace one of the GPIO pins (such as pin 21, GPIO 20) with a single-
> > purpose Debug UART TX pin, where the CPU card may print debug messages
> > in 8N1 format. Debug UART TX high/low is measured against VREFTTL.
> nope. not enough pins. you're thinking in terms of prioritising
> "Technical End-User" over "End-User".
> the volume of sales to "End User" is intended to be HUNDREDS OF MILLIONS.
> the volume of sales to "Technical End User" is expected to measure in
> the thousands.
Ok, makes sense. That's a valid design point.
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