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AM1808 sleep and wake on interrupts

Snehal Parmar
Intellectual 485 points
Other Parts Discussed in Thread: AM1808

Hi,

I want to put my AM1808 based board in low power mode (suspend to RAM mode.)

But I can not configure the wakeup event on any GPIO based IRQ. It is also not documented any where in the Reference manual.

So can I implement the some GPIO based wake up signal or I must have to use the hardware DEEPSLEEP signal ?

For our system we need the board to wake up on keypad interrupts, UART, SPI interrupts etc.

Any help will be appreciated.

 

 

  • 0
    TI__Intellectual 1265 points

    Snehal,

    Suspend to ram uses the processor deepsleep mode.

    From the processor perspective, deepsleep can exit only with the external DEEPSLEEP signal or via internal RTC alarm.

  • 0 in reply to IanB
    Intellectual 485 points

    Ian,

    Thakyou for the clarification.

    Thanks,

    Snehal

     

  • 0 in reply to IanB
    Intellectual 485 points

    Ian,

     

    Do you have an estimate of how long the processor takes to enter and exit the deep-sleep mode on Am1808 ?

    As of now it takes  ~250 milli-seconds to enter and ~350 milli-seconds to exit sleep mode, on our board. Seems to be on a higher side.

    This information is obtained for the rctwake command log.

     

    If it would take like 20-50 milli-seconds to enter and exit deep-sleep then rtcwake will be a good option for us.

     

    Thanks,

    Snehal

     

  • 0 in reply to Snehal Parmar
    TI__Intellectual 1265 points

    The numbers you are seeing look correct.  I have read other reports of 300-400ms for the full wakeup.

     

    Note that the physical hardware mechanisms to wakeup the device take much less time, and most of this time that you are seeing is software restoring the kernel and environment to the previous state.

  • 0 in reply to IanB
    Expert 1330 points

    Hi,

    I am also facing similar issue with AM1808.

    When i issued the coomand it goes to sleep mode and it is not wakeup using with this commad.

    root@am1808-evm:~# echo mem > /sys/power/state

    PM: Syncing filesystems ... done.
    Freezing user space processes ... (elapsed 0.02 seconds) done.
    Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
    Suspending console(s) (use no_console_suspend to debug)

    How to wakeup from sleep. Always my lcd screen shows white. using with this command we saved 100mA. Please give me any suggestions.

    Regards,

    Kumar