ludespeedny
Posts: 103
Joined: Mon Oct 01, 2012 6:55 pm

powering the pi and camera

Mon May 26, 2014 10:46 pm

How do you power the pi and camera? Do you just use the power to micro usb, or do you go right to gpio pins?
Reason I ask is that I am thinking that I need more power to my pi with the camera on constantly.
I have a 5v .7a psu I am currently using but keep getting lockups. I am trying with a 5.1v 2a psu (android charger) and seems stable for now although I don't ever see the full 5v when measuring tp1+2. I normally see about 4.6v.
Any suggestions of power supplies to go with?

kaos
Posts: 108
Joined: Mon Mar 26, 2012 8:14 pm

Re: powering the pi and camera

Tue May 27, 2014 9:20 am

ludespeedny wrote:How do you power the pi and camera? Do you just use the power to micro usb, or do you go right to gpio pins?
I went with the gpio for my camera setup, mostly for convenience. If you do, remember to use a fuse or other overcurrent protection, as you will be bypassing Raspi's own self-resetting fuse, F3.
ludespeedny wrote:I have a 5v .7a psu I am currently using but keep getting lockups.
700mA is marginal for use with the camera module. I suggest 1A as a practical minimum, and higher if you are using other power-hungry peripherals at the same time. 700mA might do, if it's a high quality supply that doesn't blink at power surges up to it's full rating, and you are using no other peripherals.
ludespeedny wrote: I am trying with a 5.1v 2a psu (android charger) and seems stable for now although I don't ever see the full 5v when measuring tp1+2. I normally see about 4.6v.
That is a bit on the low side, certainly outside the generic TTL 5V +/- 5% spec. Interesting that the system is stable with this supply; possibly the raspi/cam setup is more sensitive to voltage drop from power surges (which a higher current power supply should more easily swallow), than absolute voltage level. You might want to measure the voltage drop over F3 (located near the micro-USB connector, possibly on the bottom side of the PCB), to see if that is the cause of the low voltage. There will always be some voltage drop there of course, but 0.5V is a bit much. Powering through the gpio pins will avoid that drop, but bear in mind that there will be some (though hopefully lower) voltage drop over the fuse you use instead.

--
Best regards, Kári

ludespeedny
Posts: 103
Joined: Mon Oct 01, 2012 6:55 pm

Re: powering the pi and camera

Tue May 27, 2014 2:08 pm

I'll try measuring the voltage at tp1+2 again today. How do I measure the drop?
Also, no matter what psu I use I can't seem to get much over 4.6.

Do you have any pics of how you put a fuse on the gpio?

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algorithm
Posts: 183
Joined: Mon Nov 25, 2013 9:09 pm
Location: Flatland

Re: powering the pi and camera

Tue May 27, 2014 2:47 pm

ludespeedny wrote:Also, no matter what psu I use I can't seem to get much over 4.6.
Perhaps try using a thicker/shorter cable to avoid voltage drop?

ludespeedny
Posts: 103
Joined: Mon Oct 01, 2012 6:55 pm

Re: powering the pi and camera

Tue May 27, 2014 2:48 pm

algorithm wrote:
ludespeedny wrote:Also, no matter what psu I use I can't seem to get much over 4.6.
Perhaps try using a thicker/shorter cable to avoid voltage drop?
Right now the cable is only about 3ft and I don't have any shorter.
I'll have to buy some more.

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algorithm
Posts: 183
Joined: Mon Nov 25, 2013 9:09 pm
Location: Flatland

Re: powering the pi and camera

Tue May 27, 2014 3:06 pm

That seems short enough, though. Or at least not unusually long. So perhaps that's not it.

ludespeedny
Posts: 103
Joined: Mon Oct 01, 2012 6:55 pm

Re: powering the pi and camera

Thu May 29, 2014 11:28 pm

I was able to get better readings today, here are the results:
All readings are taken with the same sd card, cable, wifi dongle, and camera running and no overclock. Measured at TP1+TP2
With the 5v 2a adapter: average 4.8v
With the 2 different 5v 1a adapters: 4.65

Do you suggest just sticking with the 5v 2a adapter?

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