RTC only mode on AM335x - Risks and Timer based on/off

K Md Feroz Irfan

Dear Champs!

We have one technical query regarding the RTC Only mode of AM335x.
Assume processor is in RTC only mode and we have configured the RTC timer for lets say 1 hour. If RTC timer overflows whether it will interrupt the processor ?

If not any other wake up feature available in RTC only mode with respect to RTC timer overflow.

Best Regards

Feroz

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi Feroz,

In RTC only mode the processor is switched off. In this mode the RTC wakes up the PMIC and the processor practically executes a cold start. See sections 8.1.4.3.5 and 20.3.3.8 in the AM335X TRM Rev. J.

0 K Md Feroz Irfan over 11 years ago in reply to Biser Gatchev-XID

TI__Expert 7225 points

Hi Biser,

Thanks. Need some more clarity:

In datasheet section 8.1.4.3.5 RTC-Only mode it is written as " Wakeup from RTC-only mode can only be achieved using the ext_wakeup0 signal "

So how processor will wake up if the RTC timer overflow condition occurs. Whether any GPIO pin (output pin) is available in processor for indicating a RTC Timer overflow condition.

Best Regards

Feroz

0 Biser Gatchev-XID over 11 years ago in reply to K Md Feroz Irfan

TI__Guru**** 393215 points

See Table 20-62 in the TRM. The PMIC_PWR_EN output is turned on by ALARM event OR ext_wakeup event.

0 K Md Feroz Irfan over 11 years ago in reply to Biser Gatchev-XID

TI__Expert 7225 points

Thank you Biser!

Our concern was the statement in DM that only external wakeup can trigger the wakeup....from RTC only mode. So even the RTC timer can.....

Hope we can make changes in DM/TRM appropriately...

Thanks again!

Best Regards

Feroz

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RTC only mode on AM335x - Risks and Timer based on/off