Using the AM335x's PRUSS in deep sleep mode.

Nate Fudim

Hello,

I am using ti's 3.14 linux kernel on the beaglebone black. In my application I am trying to put the am335x in deep sleep mode, while still keeping the pru in operation(doesn't matter to me if its at a lower frequency). After researching online I found out that the pru can only be kept in operation in deep sleep 1 and above, but the kernel im using only has standby mode and deep sleep 0 mode (with gpio0 wake up) implemented. Does there exist an OS with deep sleep 1 implemented or is there any simple hack I can do to keep the PER domain awake as that seems to be the only difference between deep sleep 1 and deep sleep 0.

Thanks.

over 9 years ago

0 Joe G. over 9 years ago

TI__Mastermind 25886 points

Believe this is in the HW from pp. 1125-1126 of http://www.ti.com/lit/ug/spruh73m/spruh73m.pdf

Deepsleep1 Power domains:

PD_PER = ON

Deepsleep0 Power domains:

PD_PER = OFF

0 Nate Fudim over 9 years ago in reply to Joe G.

Prodigy 80 points

So is there any simple hack I can do so that when or before I run the deepsleep0 command "echo -n "mem" > /sys/power/state", I can prevent the m3 firmware from shutting down PD_PER?

0 Joe G. over 9 years ago in reply to Nate Fudim

TI__Mastermind 25886 points

Sorry, not sure if I fully understand the question.

But if you want to use Deepsleep1 (Keeping PD_PER=ON) instead of Deepsleep0 from Linux, you just type (in theory. I just not have tried in a while): echo standby > /sys/power/state
as documented here: processors.wiki.ti.com/.../AM335x_Power_Management_Standby_User's_Guide

Of course you will not get as low power as with Deepsleep0 (which for reference is documented here: processors.wiki.ti.com/.../AM335x_Linux_Power_Management_User_Guide )

Processors

Processors forum

Using the AM335x's PRUSS in deep sleep mode.