We're building an OMAP-L138 board that we'd like to be able to programatically put into DEEPSLEEP and wake with an external signal. SPRUH77A (OMAP-L128 Ref Manual), page 218 describes the procedure for entering deep sleep as follows:
7. Configure the DEEPSLEEP pin as input-only pin..
8. The external controller should drive the DEEPSLEEP pin high.
9. Configure the desired delay in the SLEEPCOUNT bit field...
10. Set the SLEEPENABLE bit in DEEPSLEEP to 1
11. Begin polling the SLEEPCOMPLETE bit...
12. The external controller drives DEEPSLEEP log to initiate Deep Sleep mode.
My questions are:
1) Is it okay to use GPIO lines to trigger DEEPSLEEP after step 10?
2) If the answer to 1 is no, then does the OMAP require a transition from high to low on the DEEPSLEEP after SLEEPENABLE is set to 1, or does it just look for a low? If the former, then it seems like step 8 is required to occur before step 10 and step 12 is required to happen after. But if the latter is adequate it seems like step 8 could be omitted and step 12 could happen anytime before 11, which could simplify the circuitry necessary to drive the DEEPSLEEP pin.
Thanks,
John Filo