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Boot on power up with attached HDMI cable

Unread postPosted: Sun Nov 24, 2013 9:19 am
by jolmer
Hi everyone,

I think I have a solution to the issue where the XU doesn't boot on power up, when a HDMI cable is attached. I shot a brief and raw video with my cell and post it here:

https://www.youtube.com/watch?v=vw5e33j-zVc

I used a small elco (electrolytic condensator) of 4.7 uF to do the auto power on. The positive pole of the elco is attached to pin #1 and the negative pole to pin #12 of the I/O connector. This briefly shorts those two together, but not continually. That would cause the XU to power down after 10 seconds.

I hope this will help others with this issue.

Kind regards

Jolmer Tilstra

Re: Boot on power up with attached HDMI cable

Unread postPosted: Mon Nov 25, 2013 1:02 am
by jolmer
A little addition to the workaround above; it's possible to use elco's in the range of 0.47 to 4.7 uF and a operating voltage of at least 6.3 Volt. Keep in mind: the higher the capacity of the elco, the longer the 'on button' is 'pushed' at start up. Too long will result in a power down, like in a way that is usual on large PC's.

Keeping the capacity low has also the advantage of short power brown outs; the elco needs to be discharged on power down to be effective as a power on boot up aid, so with lower capacity this will take less time. The only thing to pay attention to is to pick the capacity large enough, so the XU will recognize the power on boot up.

~Jolmer

Re: Boot on power up with attached HDMI cable

Unread postPosted: Mon Nov 25, 2013 11:01 am
by odroid
Great !
According to our test, the 1uF~2.2uF seems to be an optimal value.
We will also try some ceramic capactiors and share the result.

Thank you !

Re: Boot on power up with attached HDMI cable

Unread postPosted: Mon Nov 25, 2013 11:35 pm
by jolmer
odroid wrote:Great !
According to our test, the 1uF~2.2uF seems to be an optimal value.
We will also try some ceramic capactiors and share the result.

Thank you !

You're welcome!

Indeed, that range seems most suitable. I intend to use a axial elco...

http://www.conrad.nl/ce/nl/product/4720 ... o-3540V-1F

... directly soldered to the back of a 2 x 15 pin 2 mm pitched IDC connector:

http://www.conrad.nl/ce/nl/product/7358 ... 43-30-60-1

This is a clean way to build a permanent version of this 'hack'. I'll post some pictures when I get my stuff and build this setup.

~Jolmer

Re: Boot on power up with attached HDMI cable

Unread postPosted: Tue Jan 21, 2014 12:24 am
by spcano01
Any update to this? Would love a permanent on/off button where I didn't need to undo hdmi to turn back on! Besides that, LOVE the XU lite.

Re: Boot on power up with attached HDMI cable

Unread postPosted: Fri Feb 14, 2014 11:46 pm
by rompelstilchen
spcano01 wrote:Any update to this? Would love a permanent on/off button where I didn't need to undo hdmi to turn back on! Besides that, LOVE the XU lite.


yep, the whole no ON/OFF button is really a painful concept

Re: Boot on power up with attached HDMI cable

Unread postPosted: Thu May 18, 2017 12:22 am
by hetii
Hello,

I also have trouble to use external power switch.
In my case I also need to have power status of odroid to know when cut of power from PSU.

So here is my solution: The pullup resistor can be in uC like in my case or external one.
In the below picture I connect it to pin 1 but not sure if this pin is always powered, if not then connect it before main switch of your power.

Also note that PWRON (pin12) should be connected to colector of this NPN.

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