GTA04 Block V4

Andy Green andy at
Fri Aug 15 18:18:18 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| Andy Green wrote:
|> Hash: SHA1
|> Somebody in the thread at some point said:
|> |> Really USB host is very "usable" and flexible for these tasks.
|> | It mandates a microcontroller, USB and programming,
|> So what?
| For some things - switches and buttons - it's a complication beyond just
| jamming an I2C peripheral on there.

Is that even true?  You still need a button <-> I2C device.  Then you
might as well have a USB <-> button device and so not need to open the
case -- and get power coming cleanly.  And your button / whatever works
on a laptop or desktop PC.

|> | and can't do wakeup well.
|> Citation needed.
| To clarify - as I understand it the likely power draw required for the
| SC* to be awake enough to do USB suspend negotiations is rather high.
| Plus it'd require a 5V source alive all the time.

What's an SC*?

If all your device is doing is a button, you can take it down during
suspend and re-enumerate it on resume.  Otherwise USB specifies clearly
about max suspend current, 500uA.

| 20 way 0.5mm FPC connectors are available off-the-shelf inexpensively.
| This would make it useful for expansion, in addition to its primary
| purpose, in a way that the existing one is not.

It's wrongheaded.  Use a standard interface that already exists.  This
week I tore my debug flat cable, they are evil compared to standard and
robust USB connector.  I will definitely be agitating that we forget
about any kind of nonstandard internal connector.

- -Andy
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