kenmoini
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Power Pi Zero from GPIO?

Fri Dec 04, 2015 5:34 pm

With the Zero only having the one micro USB port, I'm wondering if it's possible to power the Zero via the GPIO port? Set the ground, and 5v pins and it should be able to boot and leave the USB port available correct?
My reference for the pinout is from these docs
https://ms-iot.github.io/content/en-US/ ... gsRPi2.htm
And since the Zero has the same 40 pin GPIO port, I'm assuming this is possible? It's be a while since I've dusted off my Pi but I do recall reading the ability to power the Pi from the GPIO port, maybe?

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Douglas6
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Re: Power Pi Zero from GPIO?

Fri Dec 04, 2015 5:42 pm

Yes, you can power the Zero from the GPIO pins. What you cannot do is to use the power USB port for anything but powering the Zero.

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mahjongg
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Re: Power Pi Zero from GPIO?

Fri Dec 04, 2015 5:52 pm

The zero has no polyfuse, so there is no downside to powering from the GPIO's (except you can reverse, or over-volt the power), so be careful!

redorzed
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 12:07 pm

Hi,

Sorry for dragging up an older post, but it is relevant to my question.

I have a Pi Zero & would like to power it from a 2A 5v transformer, via the GPIO - my question is what fuse should I put between the transformer and the Pi?

The Pi is to run OSMC or Kodi, with the HDMI out to TV and a Wifi adapter on the USB port.

Thanks in advance :)

Zed

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FTrevorGowen
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 5:16 pm

redorzed wrote:Hi,
Sorry for dragging up an older post, but it is relevant to my question.
I have a Pi Zero & would like to power it from a 2A 5v transformer, via the GPIO - my question is what fuse should I put between the transformer and the Pi?
The Pi is to run OSMC or Kodi, with the HDMI out to TV and a Wifi adapter on the USB port.
Thanks in advance :)
Zed
Do you really mean a 2A 5V transformer (ie. an A.C. device - I hope not)? I would suggest that a 5V 2A DC PSU needs a fuse rated at <=2A (to protect the PSU) but a fuse rated <=1.5A might be better (protection) for the Pi Zero. What type of fuse were you thinking of?
Trev.
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my 2xP3A+, P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

redorzed
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 6:10 pm

FTrevorGowen wrote:Do you really mean a 2A 5V transformer (ie. an A.C. device - I hope not)? I would suggest that a 5V 2A DC PSU needs a fuse rated at <=2A (to protect the PSU) but a fuse rated <=1.5A might be better (protection) for the Pi Zero. What type of fuse were you thinking of?
Trev.
Hi,

Looking at this sort of thing AC > DC 5V 2A

Hadn't really thought through the fuse yet, s'why I was asking on here for advice :)

Something like These jobs?

The smallest car-type blade fuse is 2A.

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FTrevorGowen
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 6:37 pm

redorzed wrote:
FTrevorGowen wrote:Do you really mean a 2A 5V transformer (ie. an A.C. device - I hope not)? I would suggest that a 5V 2A DC PSU needs a fuse rated at <=2A (to protect the PSU) but a fuse rated <=1.5A might be better (protection) for the Pi Zero. What type of fuse were you thinking of?
Trev.
Hi,
Looking at this sort of thing AC > DC 5V 2A
Hadn't really thought through the fuse yet, s'why I was asking on here for advice :)
Something like These jobs?
The smallest car-type blade fuse is 2A.
I suspect that that "sort of thing" will not be well enough regulated - why not use a standard uUSB connected PSU (remove the uUSB connector and wire directly to the appropriate GPIO pins) + inline fuse? (The O.P.'s reference to "freeing up" a uUSB connector may be a "red herring" as that's "power only" and cannot thus be used for anything else)
Trev.
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my 2xP3A+, P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

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davidcoton
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 6:51 pm

Difficult to tell from the ebay photo, but I don't see any active regulator -- it wouldn't be necessary for powering LEDs. So probably not good enough for a Pi.

Also:
Output voltage: DC5V 2 - 4A(max)
power :10W MAX
5V2A = 10W, so 4A is not compatible with 10W. Someone who wrote that spec doesn't understand what they are writing.

Proceed with caution. Your Pi is at risk with that PSU. Better to get a standard 5V 2A (or 4A) USB PSU and use the intended power socket. Add a fuse (preferably a polyfuse, as used on the other Pis) if the PSU can supply more than 2A. If the total design load does exceed 2A, don't let it all go through the Pi, the tracks probably won't take it.
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redorzed
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 7:49 pm

FTrevorGowen wrote:I suspect that that "sort of thing" will not be well enough regulated - why not use a standard uUSB connected PSU (remove the uUSB connector and wire directly to the appropriate GPIO pins) + inline fuse? (The O.P.'s reference to "freeing up" a uUSB connector may be a "red herring" as that's "power only" and cannot thus be used for anything else)
Trev.
That's really the crux of it - are the standard uUSB PSUs any better regulated? If they are significantly better and worth the extra cost, then it's not worth cutting the plug off.

If these cheaper PSUs can be easily regulated to the required level, it seems worth a go to make a nice little enclosed box, rather than a "wall wart" sticking out of a socket.

redorzed
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 7:52 pm

davidcoton wrote:Difficult to tell from the ebay photo, but I don't see any active regulator -- it wouldn't be necessary for powering LEDs. So probably not good enough for a Pi.

Also:
Output voltage: DC5V 2 - 4A(max)
power :10W MAX
5V2A = 10W, so 4A is not compatible with 10W. Someone who wrote that spec doesn't understand what they are writing.

Proceed with caution. Your Pi is at risk with that PSU. Better to get a standard 5V 2A (or 4A) USB PSU and use the intended power socket. Add a fuse (preferably a polyfuse, as used on the other Pis) if the PSU can supply more than 2A. If the total design load does exceed 2A, don't let it all go through the Pi, the tracks probably won't take it.
Sorry David, I'm not understanding what you meant by the bit in bold?

I am understanding the bit about risking my Pi though! :o

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FTrevorGowen
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Re: Power Pi Zero from GPIO?

Thu Dec 31, 2015 9:50 pm

redorzed wrote:
FTrevorGowen wrote:I suspect that that "sort of thing" will not be well enough regulated - why not use a standard uUSB connected PSU (remove the uUSB connector and wire directly to the appropriate GPIO pins) + inline fuse? (The O.P.'s reference to "freeing up" a uUSB connector may be a "red herring" as that's "power only" and cannot thus be used for anything else)
Trev.
That's really the crux of it - are the standard uUSB PSUs any better regulated? If they are significantly better and worth the extra cost, then it's not worth cutting the plug off.
If these cheaper PSUs can be easily regulated to the required level, it seems worth a go to make a nice little enclosed box, rather than a "wall wart" sticking out of a socket.
I've measured the "loading behaviour" of quite a few uUSB (and other) PSU's so you might find that of interest:
http://www.cpmspectrepi.webspace.virgin ... plies.html
However, w.r.t. the Pi Zero, given that it is most likely to be used only with a small number of USB peripherals (w/o the addition of a powered USB hub), I would use a powerbank** for its power (and charge that from a "wall-wart" instead).
Trev.
** links to some suitable examples of such can be found in this section of my webpages:
http://www.cpmspectrepi.webspace.virgin ... pecific.22
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my 2xP3A+, P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

redorzed
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Re: Power Pi Zero from GPIO?

Fri Jan 01, 2016 12:32 am

FTrevorGowen wrote: I've measured the "loading behaviour" of quite a few uUSB (and other) PSU's so you might find that of interest:
http://www.cpmspectrepi.webspace.virgin ... plies.html
However, w.r.t. the Pi Zero, given that it is most likely to be used only with a small number of USB peripherals (w/o the addition of a powered USB hub), I would use a powerbank** for its power (and charge that from a "wall-wart" instead).
Trev.
** links to some suitable examples of such can be found in this section of my webpages:
http://www.cpmspectrepi.webspace.virgin ... pecific.22
Interesting reads there, thank you 8-)

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davidcoton
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Re: Power Pi Zero from GPIO?

Fri Jan 01, 2016 2:01 am

redorzed wrote:
davidcoton wrote:Difficult to tell from the ebay photo, but I don't see any active regulator -- it wouldn't be necessary for powering LEDs. So probably not good enough for a Pi.

Also:
Output voltage: DC5V 2 - 4A(max)
power :10W MAX
5V2A = 10W, so 4A is not compatible with 10W. Someone who wrote that spec doesn't understand what they are writing.

Proceed with caution. Your Pi is at risk with that PSU. Better to get a standard 5V 2A (or 4A) USB PSU and use the intended power socket. Add a fuse (preferably a polyfuse, as used on the other Pis) if the PSU can supply more than 2A. If the total design load does exceed 2A, don't let it all go through the Pi, the tracks probably won't take it.
Sorry David, I'm not understanding what you meant by the bit in bold?

I am understanding the bit about risking my Pi though! :o
I looked at the photo of the product on ebay. I cannot see a regulator chip -- meaning that the PSU in question is likely to give out different voltages depending on the load. It will almost certainly not stay within the +/- 0.25V needed for a Pi. Yes, it claims to be "regulated" -- either the chip to do that is hidden, or the regulation relies on transformer design (not really regulated in terms of supplies for electronic devices), or someone is telling untruths, if not deliberate lies. As explained , for other reasons I do not trust the author and I think the third explanation is likely. LEDs (for which this supply is designed) are more tolerant of varying voltage supplies.
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rpdom
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Re: Power Pi Zero from GPIO?

Fri Jan 01, 2016 10:24 am

davidcoton wrote:I looked at the photo of the product on ebay. I cannot see a regulator chip -- meaning that the PSU in question is likely to give out different voltages depending on the load. It will almost certainly not stay within the +/- 0.25V needed for a Pi. Yes, it claims to be "regulated" -- either the chip to do that is hidden, or the regulation relies on transformer design (not really regulated in terms of supplies for electronic devices), or someone is telling untruths, if not deliberate lies. As explained , for other reasons I do not trust the author and I think the third explanation is likely. LEDs (for which this supply is designed) are more tolerant of varying voltage supplies.
There's a little 6-pin chip on the underside in the pictures. Could that be the regulator?

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davidcoton
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Re: Power Pi Zero from GPIO?

Fri Jan 01, 2016 10:33 am

Doh, it probably is. In which case regulation shouldn't be an issue. For some reason I only saw the top side photo :oops:
In my book that reduces the risk to acceptable levels.
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barsznica
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Re: Power Pi Zero from GPIO?

Mon Mar 19, 2018 6:18 am

I'm looking at this as,
Output voltage: DC5V2 @ 4A(max). Power :10W MAX
5V2 is shorthand for 5.2V, so it look correct, IMO.

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