Power questions

[dragonscythe]

Hi!

I have just ordered a RPi B+ and a few peripherals, but am a little stuck on the question of how to power it.

I am planning on using it for RetroPi. I would like to plug in two controllers. I'm looking into PS2 vs wired PS3 vs wired XBOX 360 controllers, but that's another story. Regardless, I will to able to power the RPi, two controllers and a keyboard. I'm going to start out with just a wired network connection, so no WiFi dongle to worry about.

I am not sure if I should look into a powered hub. And, to understand, if I did go the powered hub route, would I plug the hub into one of the Pi's inputs and the plug the Pi's power port into one of the hub's ports? Then would I just plug the controllers and keyboard into the hub? Also, would that idea work well with http://www.amazon.com/JBtek-Raspberry-M ... roduct_top

The other route I was considering would be to still get
http://www.amazon.com/JBtek-Raspberry-M ... roduct_top
and combine it with this
http://www.amazon.com/Inateck%C2%AE-Dua ... v+2.5a+usb).
Since the on/off switch cable limits it to 2a, would this still be enough to power two controllers and a keyboard plugged directly in to the Pi?

Any advice or thoughts are well appreciated!

[fruitoftheloom]

You need to work out the power requirement of the peripherals and read this regarding max USB

https://projects.drogon.net/testing-set ... berry-pi-b

This is a good Power Supply

http://swag.raspberrypi.org/collections ... wer-supply

[dragonscythe]

Thank you for the response and the links!

One thing that I am trying to avoid with the power supply is having to unplug it to turn off the Pi every time I am done. I am trying to keep costs down, so I thought that USB on/off switch cord looked like a good solution. I'm not sure how I would do that with the linked power supply. It otherwise looks great and is reasonably priced.

I'm currently reading the max USB power link and trying to fully understand it.

[DougieLawson]

Look at how much a RPi costs to run per year. It's less than £2 for a model B/B+, less than £1.50 for an A and less than £1 for an A+.

[dragonscythe]

I guess I had not even considered just leaving it running all the time. Kind of against my nature, haha. That is a good thought, though. Any ideas as to reasons to not do this or should I just plan on shutting it down when it needs to be restarted? I only plan on using it for RetroPie and probably would not even being playing daily.

[dragonscythe]

Haha, just re-read my post. When I said "keep costs down" I wasn't thinking energy costs. I meant that I've seen some solutions that cost $30 or more for accessories that automatically turn off the Pi a couple minutes after shut down and other, similar, solutions. That cable found was around $7. But that is an interesting thought that it may not be needed at all.

[fruitoftheloom]

Thank you for the response and the links!

One thing that I am trying to avoid with the power supply is having to unplug it to turn off the Pi every time I am done. I am trying to keep costs down, so I thought that USB on/off switch cord looked like a good solution. I'm not sure how I would do that with the linked power supply. It otherwise looks great and is reasonably priced.

I'm currently reading the max USB power link and trying to fully understand it.

You can not use a general purpose on/off switch as that will just cut the power without the Operating System undertaking a controlled shutdown.

The RPi does not have an ACPI BIOS like a standard PC or Laptop:

http://www.philtopia.com/?p=1667

[DougieLawson]

I guess I had not even considered just leaving it running all the time. Kind of against my nature, haha. That is a good thought, though. Any ideas as to reasons to not do this or should I just plan on shutting it down when it needs to be restarted? I only plan on using it for RetroPie and probably would not even being playing daily.

All three of my RPis run 24*7. They don't normally get power cycled at all (unless I get a shutdown hang). All of mine normally run headless. I don't leave any TVs or monitors on all the time.

[dragonscythe]

Thanks! Good to know.

My only other concern would be that my 2-year old daughter (or anyone in my family) might power it off by mistake. If I do a software shutdown (sudo shutdown -h now) every time it's not being used but leave it on, would this be a solution (or do you have to unplug and plug back in after that command to get the device to power back on)? Then if it was powered off, no big deal, right? Although, that would be a problem if it happened more than once (lets say a power strip was turned on and off multiple times).
Anyway, I'm not trying to overcomplicate things, but I'm trying to get a grasp on what the best setup would be (staying within a reasonable price range).

[DougieLawson]

There's a small chance (worse if the system is busy writing data) that a sudden power loss will trash your SDCard.

I've pulled power, I've shorted the P6 (aka run) header and generally done bad things and haven't trashed an SDCard in more than a year. All three of my RPis run with very recent firmware and a 3.18.xx kernel, so I'm right on the leading edge.

The Raspberry Pi branded (Samsung in disguise) 8GB SDCards appear to be extremely reliable.

[dragonscythe]

Okay, good to know. Thank you! Maybe I'll give it a shot and see how it goes. I'm not really sure what to expect so far. I know that emulation station has a shutdown option, but I'm not really clear on exaclty what that does and how the Pi is powered back on (or does that just close emulation station?).

[Laurens-wuyts]

To power it back on you have a header (P6 - RUN) next to the DISPLAY connector. When you short these two pins when the pi is off, it should power back on.

http://raspi.tv/2012/making-a-reset-swi ... spberry-pi

Laurens