forward from next generation GTA discussion
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Somebody in the thread at some point said:
| Yes, we been heavily on this issue this afternoon, allen and anthony
| might have more idea about this.
I am very glad to hear any ideas.
| 2 things I really interested:
|
| * Could this be a efficient and easy control sub-system
Thinking about the sources for this MPU, we can at least do it in C. I
think what will make all the difference is if we can run EVERYTHING
interrupt-driven.
We have to have a plan that we don't make things worse by trying to make
things better :-) At 16MHz the MSP430 will take 6mA for itself, this is
death for phone standby current. So I guess we run it at 1MHz normally
when active (270uA @ 2.2V --> 594uW).
But at the deepest standby mode, the chips take 500 - 700nA @ 2.2V -->
1.5uW at 25 degrees C. We can transition out of standby in < 1us by any
interrupt, and there are 16 GPIO interrupts in play in addition to
timers and so on. And after the interrupt, the MSP430 returns back to
the standby level we set automatically.
So by having no foreground process, we can guarantee to spend the
biggest amount of time in deep standby by default. Then if there are no
~ fast activities to service, our average current consumption will be
very low, the MPU itself can get pushed out of deep suspend by actions
like button press or internal peripheral service.
Another "feature" of interrupt driven is it imposes a particular order
on the sources, you have to deal with a particular interrupt in its own
ISR, etc.
So that's "efficient". "Easy to control", there is a bit of a serious
lack of IO peripherals on MSP430, I will think about this for a bit.
| * How many things(devices) should remove from non-RTOS control
I think we get a nice win from motion sensor(s) handled by this device.
Again I will have a think about it.
- -Andy
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