[Coco] The BIGGEST PROBLEM with (So-Called) NEW CoCo Hardware...

[Dave Philipsen]

On 3/6/2017 10:11 AM, Bill Gunshannon wrote:
> ________________________________________
> From: Coco [coco-bounces at maltedmedia.com] on behalf of Allen Huffman [alsplace at pobox.com]
> Sent: Monday, March 6, 2017 9:41 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] The BIGGEST PROBLEM with (So-Called) NEW CoCo Hardware...
>
>> On Mar 6, 2017, at 8:35 AM, Dave Philipsen <dave at davebiz.com> wrote:
>>
>> It's a much neater, more professional, more reliable way of powering the Pi in an embedded situation.  I wish that they had designed it with a header for the audio, video, usb, and ethernet signals too.
> Someone even sells a rechargeable battery shield (I forget what Pi calls them), so I bet it's powering it the same way. I had assumed it had a cable running off to the USB port.
>
> __________________________
>
> One would hope if they went to the trouble to make a shield they
> included the necessary circuitry to protect the Pi and didn't just put
> batteries on a board.  it's all about engineering. The power connector
> was engineered to take power in for the Pi, the pins on the GPIO were
> not.  With four lag bolts I can bolt a trailer hitch on the bumper of my
> wife's CRV. But I sure wouldn't want to try towing my 28' camper with
> it.
>
> bill
>
With a battery backup device you'd have to have a regulator.  But if you 
already have a good 5-volt power supply then you can interface directly 
to the pins on the GPIO to power the Pi.  At most, you might decide to 
have a pico fuse inline.

Even when powered through the micro-USB port the Pi requires the power 
supply to be regulated to 5 vdc.  So the only thing that happens, 
really, is that when you power it via the GPIO header you bypass the 
inline fuse between the micro-USB and the Pi.  And, really, the fuse is 
there mostly in case someone tries to power the Pi with a supply using 
the wrong voltage.  If the voltage is higher than 6 volts, I believe, a 
back-to-back zener effectively shunts off the excess and if the current 
is strong enough it will blow the fuse.

Dave


Dave