AM3352: How to make LED flash during kernel loading?

WOODY

Intellectual 480 points

Part Number: AM3352

Hi Team,

Do you know how to config GPIO pull high/low with 1 Hz (500 ms on, 500 ms off) ?

I know I can config LED behavior in dts file like ON/OFF/BLINK, but there is no flash option.

Could you provide suggestion? Thank you.

over 2 years ago

0 Bin Liu over 2 years ago

TI__Guru**** 178611 points

Hi Woody,

By flashing, do you mean "rapidly" blinking?

0 WOODY over 2 years ago in reply to Bin Liu

Intellectual 480 points

Hi Bin,

No, I mean the LED would 0.5s ON then 0.5s OFF during kernel loading until boot finished.

0 Bin Liu over 2 years ago in reply to WOODY

TI__Guru**** 178611 points

Hi Woody,

What is the difference of blink and flash? I thought they are basically the same thing.

0 WOODY over 2 years ago in reply to Bin Liu

Intellectual 480 points

Hi Bin,

OK, I would like the LED blink with 0.5s ON and 0.5s OFF during kernel loading.

Do you know how to config it?

0 Bin Liu over 2 years ago in reply to WOODY

TI__Guru**** 178611 points

Hi Woody,

Please check the kernel device tree bindings: Documentation/devicetree/bindings/leds/common.yaml

I think you can use 'linux,default-trigger = "timer";' to specify the blinking pattern. Then the LED will start to blink once kernel loads the pwm led driver, and you need to stop the led blinking in Linux userspace once kernel is loaded.

Processors

Processors forum

AM3352: How to make LED flash during kernel loading?