LEGEND383
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Joined: Tue Mar 11, 2014 9:01 pm

Gertduino Power Supply Components

Mon Jul 06, 2015 3:12 am

I would very much like to re-add the components that are missing from the on-board power supply, but am not quite sure what is required. I know I need a barrel connector (or a direct solder connection) but what else?

On a side note, is the VIN pin on the gertduino connected in the same way as the UNO, or is this the pin that's referred to as Vext in the manual, and thus disconnected?

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Gert van Loo
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Re: Gertduino Power Supply Components

Mon Jul 06, 2015 3:08 pm

The answer is simple: DONT!
The supply was dropped because of problems with the power chip which were
detected very late in the process so it was simpler and easier to
drop the whole circuit then to design a new one.
The switch mode regulator would get very, very hot if a normal Pi supply is used.
With hot I mean >90C. You can burn your fingers.
Secondly if you supply power to the Gertduino and forget to unplug
the normal regulator, the Gertduino supply can back-feed into your wall socket supply.
If it is a cheap one it can catch fire (that is with the old Pi models, the new B+ prevents back feeding.)

LEGEND383
Posts: 9
Joined: Tue Mar 11, 2014 9:01 pm

Re: Gertduino Power Supply Components

Mon Jul 06, 2015 4:03 pm

Well that sucks :(

So I would have to use external hardware to control the power to the pi, but how would I use the gertduino to control this external hardware? The gertduino would have to be powered from somewhere, is there a way to do this? Would I need to have two 5v regulators, one feeding the gertduino and one feeding the pi with jumpers between the other gpio connectors?

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Gert van Loo
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Re: Gertduino Power Supply Components

Mon Jul 06, 2015 8:05 pm

LEGEND383 wrote:Well that sucks :(

So I would have to use external hardware to control the power to the pi, but how would I use the gertduino to control this external hardware? The gertduino would have to be powered from somewhere, is there a way to do this? Would I need to have two 5v regulators, one feeding the gertduino and one feeding the pi with jumpers between the other gpio connectors?
I can't understand the reasoning in that.
Two regulators? Why? The regulator on the Gertduino would have fed power to both the Gertduino and the Pi.
Maybe if you tell us what you want to do we might help.

LEGEND383
Posts: 9
Joined: Tue Mar 11, 2014 9:01 pm

Re: Gertduino Power Supply Components

Mon Jul 06, 2015 10:34 pm

I was hoping to have an arduino constantly running with control of the power supply going to the pi. I would then have a push button connected to the arduino which would function similarly to an ATX power button. Was hoping to use the gertduino because it also has the RTC, which is something I would really like to include in my project so that it doesn't need to have a network connection on boot to get the time.

Guess I'll look at using an uno with a separate voltage regulator for the pi and separate RTC board.

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Gert van Loo
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Re: Gertduino Power Supply Components

Tue Jul 07, 2015 6:41 am

The Gertduino board has two processors. One can be run of a 3.3V battery and has an RTC crystal.
Instead of a battery you can use an external 3.3V supply to run it from. It's main advantage is that is designed
for minimal power consumption. It has a set of diodes to switch to the Pi supply when that comes up.
Of course you can also connect a push button to it and then use it to switch an external supply on or off.

If you don't need the RTC you can reduce the "off" power consumption to zero:
You connect the push-button between the supply and the second processor.
Then you need to write a program which operates as an on off/switch:
After a power-up reset it switches the PI main power on, when the button is pressed again it switches it off and then
waits for the button release.

Phimo
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Re: Gertduino Power Supply Components

Fri Oct 14, 2016 9:32 am

I know this is an older post but I am just beginning to look at the GertDuino. I wonder if you can tell me how accurate the RTC is?

I always use the DS3231 deevices and can get them down to about +- 10 seconds per year so how does the Atmega 48 based RTC compare?

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