Start up tv when RPI powers up?

[mahuti]

I have a TV I'll be using as a monitor (for now). It doesn't have a "start up after power on" feature... so the only way to turn it on is via remote, or button press.

When the raspberry pi powers on, I want to send that button press signal to the TV to power on. Has anyone done anything like this before? I'm guessing it's kind of a simple operation using the GPIO pins to control a relay. Might need to be something between the GPIOs and the relays.. I don't know. Any thoughts?

Worse comes to worse I could use IR to do it.... but meh.

[vinegar]

what happens if you supply power to the set while holding down the power button, and keep it held?

i'm thinking it might be better to permanently bridge the power button so it's always "pressed" if possible, and handle power on/off for the whole rig, pi and tv, at a central switch.  if you start trying to do this programmatically with an optocoupler or something, murphy's law applies and you'll end up out of sync at some point when it fails to turn "off" or "on" and the pi has no awareness of the tv's state.  and anyway, you'd be adding the pi's boot time and the tv's warm-up time together to get from switch to playable since the pi's gotta boot at least a bit before you can set GPIOs, which may get annoying.

[mahuti]

I'll check. Good idea.

[vinegar]

some virtual pinball heads do this with their playfield tvs now, since so few lcds have that power setting unless you go with expensive hospitality sets.

[Slippyblade]

I power my Pi's directly off of the TV.  Just poke around with a meter until you find a solid 5v and run the Pi off of that.  That way, you turn on the TV and the TV powers the Pi.

[mahuti]

what happens if you supply power to the set while holding down the power button, and keep it held?

I tried it. It powers up when held... stays on. I put in a foot switch to test while holding the power button. Popping the floor switch on and off while holding that switch down worked a treat. So I guess at this point I just need to jumper that power switch.

I power my Pi's directly off of the TV.  Just poke around with a meter until you find a solid 5v and run the Pi off of that.  That way, you turn on the TV and the TV powers the Pi.

Now that is an awesome idea too. How do you solve the shut down issue with the RPIs? The fact that you *could* get corruption through poor shut off? Or do you just go thelma and louise on it?


 

[vinegar]

you could move roms and things you absolutely positively need writable (some config dirs, maybe?) to usb, symlink their original paths as needed or change where whatever frontend/emu you're using looks for them, and make the sd card read-only.  then at least any possible corruption issues are more likely to be limited to the specific file that was being written to.

[mahuti]

So I jumpered it. Got out the soldering iron and that's that. Works as you'd expect. Power goes on... tv is on. Sweet. Sweet. Sweetness.

Now I just need to quit screwing around with the RPI and toss it in there. I don't have controls for this cab yet, but at least i could run some sweet 80's videos off of Kodi in the background :-) This will go in the Space Encounters machine there in the middle. Someone gave it to me about 10 years ago... non working... some parts removed. I tried trading it off for years, but no takers, so It's headed into emulator land. Going to set  up the existing controls intact as a hot swappable set, but usually it will just use a tastefully done panel in a similar style with a joystick and a few buttons for most things. Man, I need to finish those 4 cabs up. Various states of disarray. Whatever... it's a basement ;-) Nobody comes down here but me.


 

you could move roms and things you absolutely positively need writable (some config dirs, maybe?) to usb, symlink their original paths as needed or change where whatever frontend/emu you're using looks for them, and make the sd card read-only.  then at least any possible corruption issues are more likely to be limited to the specific file that was being written to.

I hot plugged the Raspberry pi probably 200 times while I was originally learning all the ins and outs of it and never *noticed* any issue. I'll probably just make a backup of the initial image and then just say "screw it" for awhile. Eventually I might go with some nicer raspberry pi switch to run the whole thing. Who knows. Problem for another time.

 

[mahuti]

The only downside to this method (on this TV) is that it blocks the function of the remote control. Weird. Whatever. If I need the menu sometime I can just cut the jumper or desolder it.

[vinegar]

put a rocker switch inline lol

[mahuti]

Yeah if I cut the jumper I'll wire something else interesting in its place.

[baritonomarchetto]

Place a 1uF electrolitic capacitor in place of the jumper: you will have a small current on start and then an open circuit.
Pay attention to the polarity of the cap.

[mahuti]

1uf capacitor!!! GREAT SCOTT!!




I may actually have one of those laying around. Thanks for the suggestion btw.

[yotsuya]

1uf capacitor!!! GREAT SCOTT!!




I may actually have one of those laying around. Thanks for the suggestion btw.

He didn't say put a 1.21 Gigawatt capacitor... ;-)

[mahuti]

See... this is the right audience for that. If only I could go back in time, I could just get a decent WG monitor and be done with this.

[mahuti]

Place a 1uF electrolitic capacitor in place of the jumper: you will have a small current on start and then an open circuit.
Pay attention to the polarity of the cap.

By the way, I tried that today. No luck. I ordered some of those 1uF electrolytic caps awhile back... just got around to soldering it in. When I plug in the tv, it sounds like power goes to the sound board, but the TV now doesn't come on without using the remote.. which is what it did before I put the original jumper in place.

[keilmillerjr]

http://www.raspberry-pi-geek.com/Archive/2015/10/Raspberry-Pi-IR-remote

[baritonomarchetto]

You placed it with the right polarity, do you?

[mahuti]

Yes.  When that didn't work I tried it the other way. Neither way works. Shrug.