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Wiring help for Raspberry Pi portable game console

vsaari

I'm building my own variant of the portable gaming console that operates on Raspberry Pi and runs RetroPie. I have little experience on small and simple electronics projects, but wiring a Raspberry Pi raises a few questions for me. I'm using Model A+ Pi as a base, run a Chinese 5" monitor through HDMI and controller is made with tactile switches that hook up to GPIO ports. The physical design is made to look something like GameBoy Advance SP with its clamshell design.

 

The question comes with running power to the system. Because I want to make it portable, I will be using a 3.7V LiPo battery and Adafruit Powerboost 500C for power. Now I wasn't really sure how I can hook this all up together. Can I run the 5V wire from the Powerboost parallel to both the 5V GPIO pin of the Pi and to the 5V pin of the screen? Ground would also be hooked from the Powerboost to both a ground on Pi's GPIO and ground on the screen.

 

I know that the Pi can power up the screen from the GPIO port if the Pi is hooked up to an USB power source. The screen has a 26 pin bus for connecting to the Pi and if that is plugged in, it works as a power source for the screen. The screen also has touch screen, which I will not be using.

 

The screen

  • Hi Ville,

     

    (a) The Pi can be powered by connecting a 5V supply to the pins on the GPIO header. By "connecting a 5V supply" I mean connect the +5V (usually red wire) to the +5V pin on the Pi, and the 0V (usually black wire) to the 0V pin on the Pi.

    (b) You can power as many things as you like from one power source provided they all require the same voltage. You'd connect all +5V connections together, and all 0V connections together, i.e. parallel as you say. Note that you need to be sure that the sum of current consumption doesn't exceed what your power source is capable of. So, if the Pi needs (say) 1A, and the display needs 1A then you need a power source that can supply 2A minimum. These 1A figures are pulled out of the air just for example purposes, you'd need to confirm (datasheets or google or measurements).

  • in reply to shabaz

    Thanks for the help.

     

    I was thinking this might be the case, which is one of the reasons why I chose Model A+. It has a very lean power consumption and according to these figures, it might run on even as low as 250mA.

     

    I tested the Pi and the screen by plugging them to a USB power source that is rated to give out 1.35A and they both seem to run off just fine. I might try to find an even lower rated power source and see what happens.

     

    Edit. I tested it now with a low quality Chinese USB charger rated at 500mA and both the Pi and the screen are barely running. I can boot it up, but it lost power when it got to the RetroPie main menu.

  • in reply to vsaari

    After printer and scanner manufacturers started exaggerating their resolutions, everybody followed suit. So the "rating" on your USB charger doesn't mean anything.

     

    I've measured a few chargers, and some barely manage 350mA. So, it could very well be that the adafruit powerboost, rated at around 500mA, but (and I believe them) often capable of 1000mA is up to the job. But as they say at adafruit: Make sure that your LIPO can handle it. Keep in mind that to deliver 1000mA at 5V, you need around 2000mA at the LIPO (starts out at less when the LIPO as 4.2V, but increases as the LIPO drains).