Power on delay.

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TbirdMan
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Power on delay.

Unread post by TbirdMan » Sun Apr 14, 2019 9:00 am

I am currently working on a project with my xu4 to put it into a PlayStation Classic case complete with functional USB ports and buttons/LED. One annoyance I have with this that I just noticed is that to turn the board on from a powered down state, I have to hold the power on button down for a short time. I would prefer if it booted the instant I pressed the button, is this possible? if not could I just add a capacitor to the button to hold the voltage high long enough to boot it without actually physically holding the button?

phaseshifter
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Re: Power on delay.

Unread post by phaseshifter » Sun Apr 14, 2019 12:00 pm

you could do it with a relay latching circuit on the main dc power rail..there is no switch one i named the momentary switch ..sw2 cause sw1 is on the odroid..

the relay coil is connected one side to the positive rail and the other pin of the relay coil goes to sw2 there is no ground/earth from the relay coil my pic shows a ground coming of the relay pin disregard that earth,,the other terminal of sw2 goes to ground..sw2 is momentary ..pick a switch you want as long as it is push button momentary......hence sw2 is pushed the relay opens the circuit causing a momentary break in the power rail to the board causing a power loss....sw2 is let go and power is reapplied ..hence the board commences to power up and boot....phase..

EDIT:: i redraw-ed the circuit ..inc the diode and the capacitor..you could add a cap across the switch if you were compulsive..point one microfarad 100 volt d.c greencap or mkt..
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Last edited by phaseshifter on Sat Apr 20, 2019 5:57 am, edited 2 times in total.
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phaseshifter
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Re: Power on delay.

Unread post by phaseshifter » Sun Apr 14, 2019 3:18 pm

i should add that this modification is a permanent feature that needs to be put in series into your input power line cable..etc.etc..

if you push sw2 at any time while the xu4 is operating it will cause a cold reboot and may corrupt your file system and or media...

it is only meant to be used as a power up after a poweroff command or shutdown via the desktop/gui..has been issued...

also note that the only time the relay will draw current/power..is when sw2 is pressed..so it wont inhibit any loss of power too the xu4


i just wanted to make this clear..
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phaseshifter
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Re: Power on delay.

Unread post by phaseshifter » Tue Apr 16, 2019 10:54 am

just to add fuel to the fire ...i missed the diode across the relay coil um 1n4001 or similar should do the job ,,really any rectifier diode will do as long as it is silicon..
..cathode to +Tve side of the coil and anode to Gnd/Earth..
so basically in parallel with the relay coil. sw2 remains the same position in the circuit.... i`ll also add an

Code: Select all

100 volt d.c.or  .1 Mfd mkt 
green cap across the contacts of the relay this ensures longer contact life
and the diode stops back rush current from the collapsing field of the coil once power is removed ..
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TbirdMan
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Re: Power on delay.

Unread post by TbirdMan » Sat Apr 20, 2019 7:19 am

Well, that seems a bit extreme, I think I will look into other options, I know a one-shot would do the trick, maybe that is the option I should look at.

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