My PSP (PiStation Portable)

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This topic contains 6 replies, has 3 voices, and was last updated by Profile photo of ellindsey ellindsey 2 years ago.

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  • #99323
    Profile photo of ellindsey
    ellindsey
    Participant

    Here is my PSP-styled Retropie Portable implementation. I’ve been working on this since about the beginning of the year, which is why I built it with a Pi B instead of the Pi 2.0. There are several things I’d do differently if I were starting this from scratch now, but I’m happy with how it came out.

    I designed this with the aim of having good ergonomics, to have a gaming station that I could comfortably play for a few hours at a time without hurting my hands. I didn’t like the feel of the little membrane pushbuttons everyone seems to be using, and instead opted for the nice 16mm illuminated mechanical pushbuttons from Adafruit instead. They have a really smooth action and a nice mechanical feel, and they glow in different colors when I turn the power on. The overall size and placement of the buttons and analog joystick was determined by what felt most comfortable in my giant man hands, I went through several design iterations before settling on this one.

    The case is all printed on my 3D printer. There are only two printed parts, making up the front and back halves of the case, although they are huge parts that barely fit on my print bed. In the interest of saving space I decided to forgo connectors and just solder the power, video, and internal USB lines directly to the Pi board. Doing that let me fit everything but the joystick and buttons behind the video screen.

    Still working on the power control, my goal is to have push-button on and software off power instead of the dumb toggle switch I have now. No speakers, headphone output only, and the audio quality is pretty poor, but that’s what you get with the default audio out on a Pi B.

    So far I have Atari 2600, GB, GBC, and NES emulation working well. SNES works but is a little slow and the audio stutters. Still working on MAME.

    Lots more details on my blog at http://drewsrobots.blogspot.com/2015/06/building-my-psp-pistation-portable.html

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    #99748
    Profile photo of ShadowKnight
    ShadowKnight
    Participant

    Thats one beautiful pie you’ve got there. Thumbs up on your 3d design! What type of screen are you using though? I was not planning on making another handheld but I just might now. 😀

    #99760
    Profile photo of ellindsey
    ellindsey
    Participant

    The screen is part B005CFLMNC from amazon or from many other online resellers. It’s a 4.3″ TFT LCD meant for car backup cameras. I removed the rear case and mounting hardware, but kept the front case and incorporated it into my design rather than burying it inside the case like most people do.

    Surprisingly this screen runs fine off 5V, despite it claiming it needs 12V and most of these needing at least 6V to work properly.

    #99880
    Profile photo of meat
    meat
    Participant

    Very Impressive! What sort of battery life do you get while running?

    #99894
    Profile photo of ellindsey
    ellindsey
    Participant

    Not completely sure as I haven’t yet done a full test of running it with a completely full battery down to shutoff, but it looks like about 2 hours of run time. I can run it with the charge cord plugged in which extends the run time, but it still discharges faster than it charges so I can’t run it indefinitely.

    #99940
    Profile photo of ellindsey
    ellindsey
    Participant

    Working on the soft power switch. I’m working on a latch circuit which uses the GPIO14 output of the Pi to indirectly drive the Enable line on the Powerboost circuit. Tapping the red button turns it on, holding the red button for 5 seconds forces it off. The first attempt didn’t work as I didn’t realize that when GPIO14 goes low on shutdown it’s not a hard low but a soft pull-down and it’s not strong enough to turn the latch off. Going to make some changes to the schematic to get that to work.

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    #100433
    Profile photo of ellindsey
    ellindsey
    Participant

    Here’s how I have the power control circuit set up.

    I’m using a Powerboost Charger 500 circuit from Adafruit, which made the power control circuit fairly easy to build. I did have to desolder the pull-up resistor on the powerboost enable line to prevent it from turning on all the time. This circuit uses GPIO14 (the UART TX line on the Pi) as part of the latch circuit. Pressing the power button momentarily brings the enable line high, then the output from pin GPIO causes the latch to stay on. When I shut down the Pi through the Emulationstation menu, GPIO14 is brought low when shutdown is complete, which discharges the 10uF capacitor and pulls the enable line to shut power off. You can also manually turn it off by holding the power button down for about 3 seconds.

    I don’t have any feedback from the power button to the Pi to trigger software shutdown when the button is pressed, although that wouldn’t be hard to add if I wanted it. Shutting down through the menu seems to work fine for me, and the current setup doesn’t require any software modification to work.

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