AM335x - DeepSleep0 and GPIO

John J Wu

Genius 3870 points

Other Parts Discussed in Thread: AM3352

Can the state of GPIO output pins be preserved during DeepSleep0.
Can USB peripheral, or at least its power control output stay active during DeepSleep0.

over 13 years ago

0 Biser Gatchev-XID over 13 years ago

TI__Guru**** 393215 points

Hi John,

According to the AM335X TRM, Table 8-13 the PD_PER power domain is off during Deep Sleep 0 and all of its context is lost, if not previously saved to SDRAM (SDRAM is in self-refresh during Deep Sleep 0). The USB controller and GPIO1...3 are part of the PD_PER power domain (Table 8-26), so they cannot be preserved in this power mode.

Best Regards

Biser

0 John J Wu over 13 years ago in reply to Biser Gatchev-XID

Genius 3870 points

Thanks Biser.

0 John J Wu over 13 years ago in reply to John J Wu

Genius 3870 points

Biser, even if the power supply for GPIO is on (according to the TRM, the power supply for the IO can be on when AM3352 is put in deepsleep0 mode), can the IO state be retained?

Thanks,

John

0 Biser Gatchev-XID over 13 years ago in reply to John J Wu

TI__Guru**** 393215 points

Hi John,

Table 8-13 in the TRM states that:

"PD_PER peripheral & CortexA8 / MPU register information will be lost. On-chip peripheral register (context) information of PD_PER domain needs to be saved by application to SDRAM before entering this mode."

The I/O state is driven by register information, so I don't see how it can be retained.

Best Regards

Biser

0 UNA over 13 years ago in reply to Biser Gatchev-XID

Mastermind 7980 points

Hi Biser

Is it better thinking that IO status is undefined when PE_PER was turn off ?

Or register value will return to Reset value?

Best regards、

Chi

0 Biser Gatchev-XID over 13 years ago in reply to UNA

TI__Guru**** 393215 points

Check Section 8.1.4.3 in the AM335X TRM. Subsection 8.1.4.3.4 is about Deepsleep0.

0 UNA over 13 years ago in reply to Biser Gatchev-XID

Mastermind 7980 points

Hi Biser

I can not find a point of TRM that status of IO and registers when PE_PER was turn off.

I want to know the state of the pin when PD_PER was turned OFF. Hi? or Lo? or Hi-Z?

Best regards、

Chi

0 Biser Gatchev-XID over 13 years ago in reply to UNA

TI__Guru**** 393215 points

Have you looked here: http://processors.wiki.ti.com/index.php/AM335x_Linux_Power_Management_User_Guide#Lower_standby_power_via_optimum_pad_configuration_during_suspend-resume

0 UNA over 13 years ago in reply to UNA

Mastermind 7980 points

Biser

Sorry to keep pestering you.

I understand that PINMUX set to GPIO during the sleep mode.

but I'm not sure status of GPIO pin(except GPIO0) during suspend.

For example, When I was set as follows:

mcasp0_aclkx.gpio3_14=0x27 > suspend_pad_conf

What is the status of GPIO3[14] pin ? (input/output?, Hi/Lo/Hi-Z?)

Best regards、

Chi

0 JJD over 13 years ago in reply to UNA

TI__Guru* 95521 points

Chi, the status of all pins during suspend will depend on the pad configuration set in the conf_* registers before going to suspend. As Biser states, you will not be able to drive any signal during suspend because power domains will be shut down, but you can set pullup/pulldown on each pin using the conf_* registers (this is what the wiki explains)

Regards,

James

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AM335x - DeepSleep0 and GPIO