julyjim
Posts: 117
Joined: Tue Jan 31, 2017 5:04 am

Raspberry Zero power spec?

Thu Apr 19, 2018 12:30 am

This post is a result of another discussion in this forum.
After letting Mrs Google drive me nuts basically linking ALL my requests for Zero spec to same copy of BCM2835 datasheet. Fine.

Nowhere does it say what is current capacity of plain GPIO port.

For real - I want to connect multiple I2C expanders to Zero.

So how much current can I SAFELY get from BCM2835 SDA/SCL ports?
Or any GPIO port?

A link to real hardware spec would be nice .

No, I do not want to "try and watch for smoke method".

wh7qq
Posts: 1475
Joined: Thu Oct 09, 2014 2:50 am

Re: Raspberry Zero power spec?

Thu Apr 19, 2018 1:30 am

I have not noticed any spec for the sda/sdl ports specifically but the gpio spec probably applies...15 ma for any gpio port.

User avatar
Imperf3kt
Posts: 3860
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Raspberry Zero power spec?

Thu Apr 19, 2018 2:21 am

16mA per GPIO. 50mA max (so if you use 5 GPIO,, 10mA each)

The 3v3 and 5v pins are not part of the GPIO.


Information from raspberrypi.org, not google.com
55:55:44:44:4C
52:4C:52:42:41

julyjim
Posts: 117
Joined: Tue Jan 31, 2017 5:04 am

Re: Raspberry Zero power spec?

Thu Apr 19, 2018 1:54 pm

Thanks
Just out of curiosity - could you post the link where you got the info?

User avatar
Imperf3kt
Posts: 3860
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Raspberry Zero power spec?

Thu Apr 19, 2018 11:32 pm

Sorry, I am afraid I cannot find it.
55:55:44:44:4C
52:4C:52:42:41

julyjim
Posts: 117
Joined: Tue Jan 31, 2017 5:04 am

Re: Raspberry Zero power spec?

Fri Apr 20, 2018 1:21 am

No problem.
I am keeping a "lab log" of my development and found thus note

"60mA " of power consumption of Zero - "unconfirmed".

Then I recall I got it from somebody who measured Zero power draw.

Nothing to indicate Zero port power output, of course.
But seem to follow the same "business" trend of not supplying much of real data for the device.
Perhaps Broadcom is to blame?

wh7qq
Posts: 1475
Joined: Thu Oct 09, 2014 2:50 am

Re: Raspberry Zero power spec?

Fri Apr 20, 2018 7:33 am

If you don't believe the spec, go ahead and sacrifice an RPi or two by loading them more. You aren't sacrificing much if it smokes. It is probably a little conservative but its like a parachute to those of us who don't sky-dive...not to be counted on but better than going down with a burning aircraft. If you feel like a river-boat gambler, go ahead and burn 'em. I would not design for even that much 'cause I like stuff to last. The CPU will throttle back if it gets too hot but that probably won't help a GPIO overload.

I expect neither Broadcom or the RPi Foundation want a lot of fried cpus out there but the non-profit educational foundation's motives may be purer than the corporate marketing approach you are probably more familiar with. The primary customer is schools and kids and it would be counterproductive to the educational goal to have lots of frustrated kids with overcooked Rpi's.

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 9565
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Raspberry Zero power spec?

Fri Apr 20, 2018 8:48 am

julyjim wrote:
Thu Apr 19, 2018 1:54 pm
Thanks
Just out of curiosity - could you post the link where you got the info?
https://www.raspberrypi.org/documentati ... T-V1_0.pdf
Table 8 note b
Each GPIO can supply up to 16mA, aggregate current per bank must not exceed 50mA
All the GPIOs accessible via the 40pin header are in the same bank.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

froggyfox
Posts: 8
Joined: Wed Feb 28, 2018 9:37 pm

Re: Raspberry Zero power spec?

Thu Apr 26, 2018 12:20 am

Thanks
Just out of curiosity - could you post the link where you got the info?
This is a great resource for specs:
.

julyjim
Posts: 117
Joined: Tue Jan 31, 2017 5:04 am

Re: Raspberry Zero power spec?

Thu Apr 26, 2018 1:46 am

Great article.
Little scary since I did not first notice they describe DIFFERENT I/O header than what is used on RPi 3B.
Still one cannot keep from wondering WHY Raspberry "foundation" cannot provide such info.
Broadcom is pretty much same issue.
Perhaps their philosophy is same as another "popular" device vendor - push button and flash LED "applications" only.

Return to “Interfacing (DSI, CSI, I2C, etc.)”