Powering StereoPi via 40 way GPIO Header

StereoPi hardware discussion
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fraserbarton
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Powering StereoPi via 40 way GPIO Header

Post by fraserbarton » Sun Oct 06, 2019 12:12 pm

Does anyone know if it is possible to power the StereoPi from the 40 way GPIO header?

I want my Pi to be powered from 24V and was intending on putting a 5V switching regulator on an external board to supply the Pi and some other high IO.

It would make my design much more refined If I can just take the 5V from the switching regulator, and route it to pin 2/pin 4 for +5V and pin 6 for GND on the 40 way header.

Image

Otherwise I need to have a little dangling cable that I can attach to the 2 pin power header.

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Realizator
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Re: Powering StereoPi via 40 way GPIO Header

Post by Realizator » Sun Oct 06, 2019 7:52 pm

Hi Fraserbarton,
To say briefly, pins 2 and 4 are sitting on the same line as +5V pin on power connector, as shown on this picture:
Image

This is correct if power switch is turned On. So you can do your idea with routing 5V to pins 2/4 and pin 6 to GND.
Eugene a.k.a. Realizator

fraserbarton
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Re: Powering StereoPi via 40 way GPIO Header

Post by fraserbarton » Wed Oct 09, 2019 11:38 am

Realizator wrote:
Sun Oct 06, 2019 7:52 pm
Hi Fraserbarton,
To say briefly, pins 2 and 4 are sitting on the same line as +5V pin on power connector, as shown on this picture:
Image

This is correct if power switch is turned On. So you can do your idea with routing 5V to pins 2/4 and pin 6 to GND.
Do you know if there is any need to use any external protection to voltage spikes such as TVS diodes, fuses and capacitors?

On the Raspberry Pi 3 I have seen that powering from the GPIO header is not the same as powering from the MicroUSB port (Don't worry I am aware that the MicroUSB port on the StereoPi is just for flashing) as it bypasses a fuse and protective diode. It's doable but people say its not as safe for the board.

Having looked at the schematics it seems that the 2 pin power header and pin 2 and 4 on the GPIO header are directly connected when the switch is closed as you say.

Do you have any input with regards to that? Don't worry if not as I can't see myself resisting the urge to just power straight through the GPIO header.

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Re: Powering StereoPi via 40 way GPIO Header

Post by Realizator » Wed Oct 09, 2019 12:36 pm

Ok, let's go to the advanced users zone :-)
In our "before-the-stereopi" projects we used a lot of Raspberry Pis of all sizes (big size, A/A+ and Zeros). In most cases we were need to attach a high power consuming devices (long-range WiFi dongles etc.). And we faced a problem with power management on a Pi. Almost always we used soldering to the pads on the bottom part of the Pi to connect power directly to the USB devices.
fraserbarton wrote:
Sun Oct 06, 2019 12:12 pm
Having looked at the schematics it seems that the 2 pin power header and pin 2 and 4 on the GPIO header are directly connected when the switch is closed as you say.
That's why in the StereoPi we implemented direct power schematics. It means power goes directly from your power source to the power lines of USB connectors and GPIO pins, without any control from Broadcom's SoC side.

So we suggest that advanced users will be glad to find this solution and use it in their projects. That is having a BEC on your drone you can use several ways to power-up StereoPi-based solution.
fraserbarton wrote:
Sun Oct 06, 2019 12:12 pm
Do you have any input with regards to that? Don't worry if not as I can't see myself resisting the urge to just power straight through the GPIO header.
To say briefly, the most power-sensible element is RPi Compute Module. That is, ideally, you need to provide 5V (+/- 0.5V) without any aggressive noise and drawdowns. For example, if you use LiPo battery with insufficient current for your copter, and while aggressive fly your power voltage (BEC or other converter) will go to 4V or lower, CM3 will reboot. The second element - your USB devices. Taking two these points into account will help you to understand, if your powering approach is correct.
Eugene a.k.a. Realizator

cjonesy20
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Re: Powering StereoPi via 40 way GPIO Header

Post by cjonesy20 » Thu Oct 10, 2019 4:50 pm

I am successfully powering my StereoPI using this shield that has a 12V to 5V buck converter on it.

https://copperhilltech.com/pican3-can-b ... s-and-rtc/

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Re: Powering StereoPi via 40 way GPIO Header

Post by Realizator » Thu Oct 10, 2019 7:04 pm

Whoa! Cool!
If it is not a secret, what will you use CAN bus for?
Eugene a.k.a. Realizator

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