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Building a handheld game console, need to work a few things out.

segadude

I will be making a handheld game console using the Raspberry Pi. But there is a few things I need to work out. First off I need to know how to power both the Raspberry Pi and an lcd screen that draws 12v of power off of batteries. I read that the Raspberry Pi can be powered by AA batteries. If my calculations are correct I will require 8 AA batteries just to power the screen alone. What is the minimum number of AA batteries needed to power the Raspberry Pi? More than 8 AA's doesn't seem very practical though. What other types of batteries could I use? Second, I don't know what material to make the case out of. I was thinking wood but that doesn't seem practical at all. What do you suggest I make the case out of? Lastly I need to pick which linux distro i'm going to use. I was just gonna download the x86 versions of each and run them in a virtual machine. But, is there a way I can test out the actual distros that will run on the Raspberry Pi? Like with some sort of emulator? If there is an emulator, will I be able to set it up and transfer to an sd card to use on my real Raspberry Pi when I get it? Thanks in advance for any help!

  • I plan on building a simple box from thin lexan plastic sheets. For my uses cosmetics are not really important. I'm not sure what to tell you about the batteries...  How many amps does your display draw?

     

    edited to add:  You know I might try and touch the plastic with a torch and mold a case.

  • in reply to Former Member

    It's not at all clear that the RP will run (sensibly) from AA batteries.

     

    The user guide says:

     

    The unit uses a Micro USB connection to power itself (only the power pins are connected - so

    it will not transfer data over this connection). A standard modern phone charger with a micro-

    USB connector will do, but needs to produce at least 700mA at 5 volts. Check your power

    supply's ratings carefully.

     

    Apart from the fact that many standard USB ports won't proivide this much power (and according to the USB spec are not obliged to)  the RP people don't say what range of supply voltage is acceptable or what the average or peak current demand will be.

     

    Let's assume 5V @ 700mA.

     

    To get the best life from an AA cell you must run it down to 0.9 and ideally 0.8V.

    Unfortunately 700mA is far too much current for an AA cell - Duracell reckon 3 hours life down to 0.8V.

     

    Let's hope that the 700mA is a maximum and it doesn't use that all the time (optimism is bad engineering but this an RP project so anything goes !)

     

    For simplicity let's use a regulator which will drop 300mV at 700mA. We need 5.3V minimum which is 7 AA cells.

    If you use  a linear regulator it will waste  a lot of the energy from the batteries because it will be dropping 5.5V when the batteries are new.

    So you had better use a switching regulator and if it's efficient it will extend the battery life quite a bit (by about 50%).

     

    So a sensible design will use 8 x AA cells and a switching regulator and the battery life would be about 5 hours if the RP draws 700mA all the time and more if it doesn't.

     

    (That bit in the 'interview' with Harriet green when the RPi man says it will run from a couple of AA cells is stretching things a bit (to put it mildly)).

     

    You will need a different regulator to power the screen but since you don't mention the current drain I can't help. (I expect it will use alt least as much power as the RPi - possibly quite a bit more.)

     

    If you still fancy the idea let me know and I'll suggest parts for the switching regulator - but you won't be able to get a modern switcher to work without a pcb designed for the job so you'll need to find an eval board that's cheap or learn pcb layout and SM soldering.

     

    Michael Kellett