Files are up on GitHub for buttons, joystick, etc. https://github.com/othermod/PSPi-1000-Version-4.
I’ve been steadily working on v4 for the last few months, and to a lesser extent since November of last year. Many improvement have been made, and quite a few were based off feedback from the Version 3 board.
Feel free to make requests for features or improvements. Before you ask it though, this will still use the Pi Zero (or Zero W). A Pi3 will not fit without serious modification (although I’m trying my hardest to make this Pi3 Compatible for those of you that want to do the modifying), and a CM3 will take much, much more time for design (not ruling out the CM3 for something later on, but I’m holding out for something similar to the Zero but with a quad-core). This board does not use an ATmega for GPIO and analog input. This means that the USB port on the Zero stays available and that no USB hub is needed.
Hardware Changes Planned for Version 4
LCD driven using GPIO
- All LCD control will be integrated into the all-in-one, meaning no external controller will be needed.
- Backlight dimming allows for reduction in power consumption.
- Greatly improves the quality of the display.
- Runs at the same resolution as the original PSP
Improved battery charging
- Charges the battery using a switching regulator instead of a linear regulator.
- Far less heat output during charging, as well as faster and more efficient charging.
- Better charging rates on depleted batteries
- Precision battery voltage monitoring. If included, this would allow the OS to monitor the exact battery charge percentage. This would open up many other software features.
- True analog input (in the games that support it)
- Can also be used it as a mouse. I won’t be supplying the code for this (at least initially), but the capability is there.
Less soldering required
- Uses the original PSP’s method of making joystick contact, so wires don’t need to be soldered to make a connection.
- Instead of soldering to the pads on the underside of the Pi Zero (for USB and microSD), gold-plated contact spring pins will be used and the Pi will snap or screw into position.
- Easier soldering of the GPIO pins. A header will be pre-soldered to the board, so only the Pi’s GPIO pins will need to be soldered.
- This wasn’t possible in Version 3 because the LCD controller used all the available space.
- Speaker wires will still probably need to be soldered. Didn’t want to do this, but the right connectors just don’t exist.
- Integrating more features allows for lower power consumption and more control over what features are enabled and disabled
- The removal of the LCD controller removes much of the power consumption and heat generation.
- LCD can be dimmed to lower power consumption
- Audio can be switched off to lower power consumption
- My tests (with the cell phone batteries from v3) put the play time over 6 hours and command line time at 18 hours. This relies heavily on the quality and capacity of the batteries.
Better emergency shutdown circuits
- Will kill power once battery is depleted past a certain voltage (probably 3.3-3.4v). This is a hard-wired feature that won’t require software to function. It serves as a backup in case the software features aren’t working for some reason.
- There will also be a software aspect to this. The battery indication LED will begin blinking orange when the battery is low, and then the system will properly shut down when the battery reaches a certain threshhold (probably 3.5v, or whatever voltage equates to 5% remaining)
- In v3, when there is a software or Pi Zero problem, the system automatically powers the board off. This makes trouleshooting a little difficult, because you have to solder a jumper wire to keep the system on. v4 will work differently. A software or SD card problem will not cause the system to power off. Only the complete absense of an installed Pi Zero will cause a power-off. In all other situations the board will stay powered on, and the system will power off only when the power button is held.
- More accurate hole positioning, which is needed for proper joystick alignment
- Better USB port positioning
Additional indication LEDs
- Power LED has the ability to blink when the battery is low instead of staying green or orange.
- LED indication on the left side for SD card activity (or any other use for those that know how to code)
- Improved audio filtering to get rid of a little more PWM noise.
- Very similar to the audio circuit in the Pi 2.
- Speakers can be switched off using the switch on the left side (which will lower power consumption and give a little more play time)
All of the PSP’s buttons will work.
- Volume buttons will be able to adjust volume up and down.
- Display button will adjust display brightness. This may be done by just alternating brightness in 10% increments when the Display button is pressed, or may be done by pressing and holding Display and then pressing Volume+ or Volume- to adjust brightness up and down. Still working out the specifics.
- Pressing the Home button will exit games in the same manner as pressing Start+Select (thanks for the idea Thorbiörn Teddy Biörrith)
Possible Changes for Version 4
- Ability to use Lakka or Retropie
- Wireless charging using Qi. If this is included, it will be optional. There just wasn’t enough room in Version 3 to make this possible. It’s very easy to integrate.
- Some change to the way the microSD adapter is relocated to the Memory Stick Pro’s slot. Whatever the final version looks like, it will be easier to solder than Version 3.
- Constantly measure power consumption of the system.
- Add headphone jack that connects easily to the V4 board.
- Add connector to use PSP battery (3.7v batteries only).
- More analog inputs to allow for dual joysticks
- Extra inputs so more buttons can be added.
Features Requested by You Guys (I’ll add these if possible)
- HDMI output capability – this one might not even be possible when driving the RGB display
- HD resolution LCD – could use help finding one that fits the PSP 1000. Might be too much for a Pi Zero.
Test 4.3″ aftermarket LCD over GPIO– Complete Find and test expansion module to replace GPIO pins used by LCD– Complete Write/modify code to get GPIO control buttons working with expansion module– Complete Design and test circuit for charging a 3.7v lithium/lipo battery more efficiently– Complete
- Design better emergency shutdown circuit – In Progress.
- Redraw outline for the PCB – Almost there
Design and test boost circuit with PWM dimming for LCD backlight– Testing Find and test module to add analog inputs– Complete Test PSP’s original battery– Complete
- Test Lakka with GPIO buttons, GPIO LCD, and joystick – Not started yet, will happen after software is working in RetroPie
- Test Qi Wireless Charging – Not Started Yet
Check it out on GitHub