AM2634-Q1: How to let AM26x go to STANDBY mode?

Gibbs Shih

Part Number: AM2634-Q1

Hi, Expert.

My question as title description, even I read TRM section "6.2.4.1 Overview of Device Power Modes" , I still feel very confuse.

If I want let device go to STANDBY mode, I need to stuff GATED bits (bit0-bit2) as 0b111 for these register as below? Am I right?

MSS_TOPRCM_R5SS0_CLK_GATE
MSS_TOPRCM_R5SS1_CLK_GATE
MSS_TOPRCM_SYS_CLK_GATE
MSS_TOPRCM_CLKOUT0_CLK_GATE
MSS_TOPRCM_CLKOUT1_CLK_GATE
MSS_TOPRCM_TRCCLKOUT_CLK_GATE

If device wants to swap into active(RUN) mode, wake up condition as below :
• the arrival of an interrupt, whether masked or unmasked
• a debug request, whether debug is enabled or disabled
• a reset.

My question : How to generate an interrupt to wakeup device?

I guess, Only main processor cores in standby (WFI/WFE), rest of active subsystems idles.

it's mean IO (ex:gpio/CAN/SPI) is still alive, so any I/O interrupt will let R5 core enter active mode.

Am I right ?

Many Thanks

Gibbs

over 2 years ago

0 Aakash Kedia over 2 years ago

TI__Mastermind 26145 points

Hi Gibbs Shih,

Gibbs Shih said:
My question : How to generate an interrupt to wakeup device?

You need to keep one of the CPUs in WFI/WFE and need to gate other CPUs (in case you don't need them and you need to save 70mW per CPU). You need to gate all the peripherals, you don't need.

You can keep the stable clocks enabled towards GPIO/CAN/SPI based your requirement. Any interrupt from these peripherals will wake-up the CPU and you can restart the peripherals as per your requirement.

Hope it helps.

Best Regards,
Aakash

0 Gibbs Shih over 2 years ago in reply to Aakash Kedia

TI__Expert 5285 points

Hi, Askash.

Thanks your reply.

so, another question follow you mention before.

How to let one of the CPUs in WFI/WFE (STANDBY Mode)?

May I have an example for setting sequence?

Many Thanks

Gibbs

+1 Aakash Kedia over 2 years ago in reply to Gibbs Shih

TI__Mastermind 26145 points

Hi Gibbs Shih,

You can use eithr of the 2 ways -

1. Either CPU instructions like this -

#if defined(__ARM_ARCH_7R__)

__wfi();

#endif

2. or, you can use SoC signals to assert WFI. Register description is mentioned below -

Hope it helps.

Best Regards,
Aakash

0 Gibbs Shih over 2 years ago in reply to Aakash Kedia

TI__Expert 5285 points

Hi, Askash

Base on previously discussion, WFI didn't work on customer's project.

because we measure current (power) consumption, and It doesn't have any change

All experiments base on AM26x CC EVB board

May you share "WFI sample code" for us to reference?

Many Thanks

Gibbs

0 Aakash Kedia over 2 years ago in reply to Gibbs Shih

TI__Mastermind 26145 points

Hi Gibbs,

You should be checking at 1V2 rail of the device. Are you checking the correct rail ?

Best Regards,
Aakash

0 Gibbs Shih over 2 years ago in reply to Aakash Kedia

TI__Expert 5285 points

Hi, Aakash

Thanks your replies.

I will double check with customer.

(1) Beside current consumption, Do we have another way to make sure R5_Core in WFI?

(2) Is this correct way to add __wfi() macro in main function?

Thanks

Gibbs

0 Aakash Kedia over 2 years ago in reply to Gibbs Shih

TI__Mastermind 26145 points

Hi Gibbs Shih,

Gibbs Shih said:
(1) Beside current consumption, Do we have another way to make sure R5_Core in WFI?

For self-core, prefer ASM instruction to enter into WFI.

For putting the other cores into standby, make sure the non-self cores are not making any transaction into the peripherals and then use the SoC peripheral registers.

Best Regards,
Aakash

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AM2634-Q1: How to let AM26x go to STANDBY mode?