[N2+] Add an additional power (sys) LED

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milaq
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[N2+] Add an additional power (sys) LED

Post by milaq »

Hey everyone!

I want to add a power led to the front of the N2 case which correctly indicates the power status of the device.
I.e. it needs to be OFF when in suspend or powered down and ON when the N2 is running.

I found two solutuions so far. None of them is doing what I want to accomplish:
1. Using Pin 4 and 6 as a 5V power supply for the led. Problem here is that the N2 supplies ~2.5V even when the device is off.
2. Modifying the DTB to reroute the sys_led (blue led at the power supply port) to a specific GPIO. Because I am using CoreELEC this involves modifying the DTB (with unknown values, the ones in the wiki are _not_ applicable). Additionally when an update to the CoreELEC kernel is released I need to repatch.

Is there a reason for the 5V line to supply 2.5V when in suspend and can I turn it off?
Is there any other solution to this or should I just solder two wires to the sys_led and use the front led in parallel with it? Would the board be able to supply two leds at the sys_led port (with a resistor to limit the current of course)?

Thanks in advance for you help!
Cheers

EDIT:
I solved it modifying the DTB eventually (see https://milaq.net/odroid-n2/ to check what I did).
Last edited by milaq on Sat Jul 03, 2021 5:45 am, edited 2 times in total.

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Re: [N2+] Add an additional power (sys) LED

Post by odroid »

The following two links should be helpful. But, I am not sure if it is applicable for CoreELEC OS or not.
https://wiki.odroid.com/odroid-n2/appli ... key_wakeup
https://wiki.odroid.com/odroid-n2/appli ... ed_control

There seems to be 3~4mA of leak current from 5 Volt power rail in the suspend mode which can't be fixed.

milaq
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Re: [N2+] Add an additional power (sys) LED

Post by milaq »

Thanks for the feedback.
After fiddling with Z-diodes and giving up eventually, I went ahead and changed the DTB.
For CoreELEC the endpoints differ from vanilla hardkernel.

I wrote down short instructions for CoreELEC if anyone else stumbles over this:
https://milaq.net/odroid-n2/
These users thanked the author milaq for the post (total 2):
odroid (Mon Jul 05, 2021 10:15 am) • m_ueberall (Thu Jul 08, 2021 8:44 pm)

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