accellerometer test

Andy Green andy at
Thu Apr 3 16:49:20 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:

| I notice you mention only one chip is currently working as isr source.
| But isn't there two independently configurable pins connected to irqs
| from that one chip?  I didn't dig into the schematic, not sure.

We have two physical chips on there, one at the "top" near the earpiece
and one at the "bottom" near the mic.  The top one is at 45 degrees to
the bottom one.  Having two is something to do with being able to sense
the attitude of the phone in space and not just the position.

Both of the chips interrupt the CPU independently at 100Hz when they are
being read from, but only one of the CPU interrupts has the magic power
to wake from suspend -- the other one is just a regular interrupt that
can't do it.  But I don't think it will make much difference to the wake
threshold scenario since both sensors see a gross action if you pick the
phone up or whatever.

Separately, there are two INT pins on each chip, but on A6 we only
connected one of them to eliminate the pullup.  You can select any
interrupt function on to either interrupt, it didn't seem that we need
more than one at a time.

- -Andy
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