i.MX6SX: Wake A9 up from M4

[gorgo]

Hi guys,
I'm working with a UDOO Neo full board at the moment and they have a i.MX6SX embedded.
I'm a newbye in this field and I can't find a solution for my problem.

In order to achieve a low power consumption I need a sleep/awake behavior between A9 and M4.
I can put the A9 into sleep if I do

echo standby > /sys/power/stat

But I need a way to wake it up through the ttyMCC serial, so with a serial.print() from M4 sketch. T

here is no wakeup in /sys/bus/platform/drivers/imx6sx-mcc-tty/mcctty.13/power/

This is the way I would like. If it's not possible, could I use gpio? How to enable one of them?

Thank you!

[igorpadykov]

Hi Davide

please check sect.10.4.1.4.1 Power distribution i.MX6SX Reference Manual:
Main SoC logic - The main SoC logic domain contains the rest of the logic of the
SoC including CM, SRC, GPC, M4..

Power domains usage in various power modes on Table 10-1. Power Modes

(check Soc power domain). Modules which can be used marked as "on" or normal voltage.

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6SXRM.pdf

Best regards
igor
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[menegolli]

Hi Igor, 

I am Edoardo, a colleague of Davide.
Just to point out that we need to put A9 into sleep mode, while the M4 still works doing its stuff.
We use a Real Time Clock in order to keep the system in sync with our server.

The desired behavior would be: RTC wakes up M4 --> M4 does whatever and then wakes A9 --> A9 listens on the serial port and then goes back sleeping until next cycle.
Is there some kind of tutorial/example code that we can use in order to fulfill these requirements?

Thank you in advance,

Edoardo

[igorpadykov]

Hi Edoardo

as described in Table 10-1. Power Modes in Suspend(Stop) mode

SOC will be put to Standby Voltage and M4 marked as "Always Clock Gated",

so M4 could not work in this mode. BSPs and FreeRTOS can be found on

i.MX 6SoloX SABRE Development Board|NXP 

Linux Manual  (in doc linux package) Chapter 21 Low-level Power Management (PM) Driver

gives description of low power modes with examples.

Best regards
igor