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Is it possible to power the Grand Central with 5V....but not
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Is it possible to power the Grand Central with 5V....but not

by gradybooch on Wed Jun 12, 2019 3:57 pm

Adafruit documentation for the marvelous, wonderful, absolutely incredible Grand Central (yes, I like this board!) states (https://learn.adafruit.com/adafruit-gra ... al/pinouts) that

There are two primary ways to power the Grand Central:

-- Through the Micro USB port up at the top left
-- Through the DC jack at the bottom left

and goes on to observe that with the DC jack one should

Provide about 6V-12V here to power the Metro.

Is there a way to power the Grand Central with 5V NOT using the Micro USB port?

I'm using the M4 in the context of some outboard electronics that will draw about 1.5A at 5V, which means that I can't pull this through the board. Therefore, I've devised a power distribution circuit for that bit, but I hate to need a dual voltage power supply to bring 6-12v to the DC jack.

My questions are thus

-- can I power the Grand Central via the DC jack with 5v?
-- if not, is there a way I could safely bring 5v into the board other than the two primary ways listed in the aforemetioned pinout documentation?

I suppose I could stuff it in via the USB port, but I'd prefer to leave that port unused for when I need to attach this device to another computer, rather than using it just for power.

Thanks!

gradybooch
 
Posts: 8
Joined: Sun Sep 16, 2018 9:04 pm

Re: Is it possible to power the Grand Central with 5V....but

by fasteddy516 on Thu Jun 20, 2019 10:49 pm

I had a similar requirement on a project with a Grand Central and a Meanwell LRS-75-5 14A power supply that was supposed to be the common supply for everything in the system. I ended up "customizing" a USB cable by stripping off an inch of the outer jacket and isolating the 5V wire (the red wire in every USB cable I've ever seen). I clipped the red wire, insulated the part of it that comes from the host, and connected the 5V from the Meanwell supply to the part that heads into the Grand Central. This allowed me to power the Grand Central from the Meanwell supply and still connect it to my laptop for programming/etc.

It's not the most elegant of solutions, but it seemed like the best way to avoid offending the power circuitry (and bypassing the built-in protections) on the Grand Central and still get the connectivity I needed.

fasteddy516
 
Posts: 8
Joined: Wed Apr 12, 2017 10:38 pm

Re: Is it possible to power the Grand Central with 5V....but

by gradybooch on Fri Jun 21, 2019 1:52 am

Excellent hack!

In end end, I settled on a simple power distribution that routes 9v to the M4 and also a 9v to 5v 5A converter.

gradybooch
 
Posts: 8
Joined: Sun Sep 16, 2018 9:04 pm

Please be positive and constructive with your questions and comments.