January 4, 2024I’ve been shipping PSPi 6 boards in small batches for about a month. It’s going well, and I’m gradually scaling up production. I have a large batch in right now (available on backorder), and I’m shipping them as I inspect and solder components to them. I’m not announcing the availability everywhere just yet because I need to improve the soldering and testing process so I can ship faster. The backlog is about a week for orders with the Solder Avoidance Service and about 1-2 days for orders without it. I’ll update this post as availability changes.
October 9, 2023
August 20, 2023
July 21, 2023
May 23, 2023 Update
The Redesigned PSPi
Back in 2021 when I released the PSPi Zero 5, I also shared my initial plan to create the PSPi Compute. The idea was for the Compute to mirror the features of the PSPi Zero, but to run with CM4 modules. Unfortunately, a shortage of ICs, CM4 connectors, and Raspberry Pi boards delayed the progress.
I recently went back to the work on it, and ordered a new prototype today.
I’m walking back the original plan to make distinct boards for the PSPi Zero and PSPi Compute, and the goal is now to create a single universal board that works with every Raspberry Pi (40-pin and CM4). This board has a normal-looking 40-pin Raspberry Pi connector which it is compatible with all standard 40-pin Raspberry Pi boards, and a carrier board will interface the CM4 board to this 40-pin connector. This is designed for the Pi Zero and Zero 2, but will work with Raspberry Pi 3 and 4 boards, although they will not fit into the shell.
I’ve also flipped the mounting position of the 40-pin Raspberry Pi, making it compatible with pre-soldered Raspberry Pi Zero headers and eliminating the painstaking task of soldering and snipping header pins. While I can’t say yet that it will be an entirely solder-free assembly, I can say that any soldering required will be minimal.
There’s a long list of improvements and modifications I’ve made, which you can find detailed below.
The schematics/PCB files are hosted here. Please remember that these schematics probably still have issues.
Changes since PSPi Zero 5:
I’ve improved the board’s standby/sleep mode. It now cuts power to everything except the Raspberry Pi. The only limitation is putting the Pi itself into a low-power state, which, as far as I know, isn’t currently possible.
The microcontroller has been swapped out. I’ve switched from an atmega328p to an atmega8. This change reduces the cost by a dollar or two without removing any features.
I’ve improved the color depth of the LCD. It’s been upgraded from 18-bit to 21-bit DPI when using a Pi Zero and to 24-bit when using a CM4.
I’ve added pads for an extra joystick or two analog inputs.
The battery charger has been upgraded. I’ve swapped out the linear charger (TP4056) for a switching battery charger that is faster and more efficient.
The power circuit has undergone a significant redesign. This is such a substantial change that it will require its own section or video to fully explain. The end result is that the system can now run on USB power without a battery, and the power-off feature is more reliable when using high-current CM4 boards.
The left switch now connects to a GPIO, meaning it can be programmed to perform any function you desire.
I’ve added another LED on the left side. The top one still acts as the activity LED, and the bottom one can be programmed to turn on whenever you want.
Lastly (for now), I’ve fine-tuned the board shape. It now more closely matches the shape of the original PSP board.
The PSPi is an interface board that replaces the motherboard in the original 1000-series Sony PSP. This board lets you use a Raspberry Pi as the brains, which means you can either turn it into an emulation system, or just run your favorite Linux distribution.
Features (will change as I prototype them):
Works with Raspberry Pi Zero, Zero 2, Compute Module 4 (with carrier) and PSP 1000 Series Case
The board has a 40-pin Raspberry Pi connector, and you can simply plug a Raspberry Pi Zero / Zero 2 into it. A normal Pi 3 or Pi 4 can also, be used, but you’ll probably need to use an extension cable or header.
With an add-in board, this is also compatible with every CM4 variant. Some have eMMC Flash while others use MicroSD cards. Some have WiFi, and some do not. The board has to work with all of them, which means it has to accept MicroSD cards on the Lite versions, and it has to allow USB flashing.
No PSP case modification is needed. The new board shape matches the PSP’s original one very closely, and doesn’t require any case modification.
The LCD is driven directly by the GPIO pins in 21-bit and 24-bit DPI Mode 7
Works with the 800×480 LCD from Buydisplay.
The LCD backlight is dimmable and you can cycle through brightness levels by pressing the Display button. The lower the brightness, the more play time you get per charge.
Hardware volume control (VOL – and + buttons adjust volume, and the Sound button mutes and unmutes the amplifier)
Tweaked audio filter to remove most of the sub 1000Hz frequencies that the PSP speakers can’t produce
Separation between power and audio circuits, which eliminates noise in the speakers and headphones. The PWM audio is buffered, filtered, and amplified with low-noise linear regulators.
Battery and Charging
The board has a standard JST PH connector for batteries. The battery charges using the round PSP charging connector (if wanted), or from the mini USB connector on top. The new charge IC uses a buck converter instead of a linear regulator, and is capable of charging the battery at 3A. I configured the IC to charge at a maximum of 1.35A because to keep the battery in good condition, and to keep board temperatures low.
5V Boost Converter for Pi
The Raspberry Pi boards all receive 5v from an efficient boost converter.
Instead of just monitoring the voltage and detecting whether the charger is plugged in, the microcontroller can constantly monitor power usage to provide accurate information about the battery status (see Input).
The board has some basic reverse polarity protection in case your battery has a swapped pinout. The board is clearly marked + and – to prevent hooking the battery up in reverse. It’s always best not to stress-test these protection features.
The board will kill all power if the battery drains below 3.1v.
The on/off circuit got a full redesign, and it now only supplies power to the microcontroller. The microcontroller then enables power to everything else in the system. It is more tolerant to quickly powering the system off and then back on. The previous version needed a few seconds to reset after poweroff, but this new one is able to power the board back on immediately after a shutdown completes. Functionally, this is identical to previous versions. A quick push of the power button will turn the system on, a quick push when the system is on will shut the system down and power it off, and a long hold of a few seconds will kill power to the board entirely regardless of whether the Pi has completed shutting down.
The miniUSB port is properly isolated from the battery . When the system is turned off, no battery power reaches the miniUSB port. Power is also unable to backfeed to the Raspberry Pi from a powered USB device.
The miniUSB port powers USB devices directly from the battery when the system is powered on with a working Raspberry Pi, and it will range from 3.0v to 4.2v depending on the charge state of the battery. This power flows through an ideal diode, and experiences no loss in voltage.
If a USB device needs the full 5v (which may be unlikely, none of my USB devices needed 5v) or high amperage, the round charging cable can be plugged in, and the board will pass 5v directly to the miniUSB port, which will power the USB device regardless of whether the PSPi is off or on.
The miniUSB port is able to both provide and receive power. When using a USB device such as a thumb drive or keyboard, the PSPi will power the device using the battery (unless the round charger is plugged in, as stated previously). When a USB charger or other powered USB device is plugged in to the miniUSB port, the PSPi will begin receiving power and charging the battery.
The CM4 uses a lot of power. Right now, I’m using a thermal pad to move the heat from the CM4 and into my board, and it seems to be adequate and eliminates the need for a cooling fan. There’s still some testing to do, but it looks promising.
An atmega8 microcontroller handles all the input for buttons, joystick, and battery monitoring. The microcontroller is constantly calculating, storing, and transmitting button and analog statuses to the Raspberry Pi using I2C. The firmware can be updated using the FPC-10 connector.
The microcontroller has 6 ADCs in use. Two are used for the joystick, one for battery voltage detection, one for battery amperage detection, and two are available for anything you want to use them for. The joystick readings are sent directly to the Raspberry Pi, and the voltage and amperage calculations are done on the microcontroller before being sent to the Pi. The remaining pins are used for buttons, data transfer, and PWM output for the LCD brightness control.
The Raspberry Pi code is all written in C and runs more efficiently than the Python scripts used previously.
Prototype 1 – ordered February 1, 2021:
Rough proof of concept. I reused as much as I could from PSPi v4, just to see whether this project is doable with the CM4.
The ATMega328p microcontroller is up and running with very beta firmware. So far, I have the display, audio, buttons, joystick, and battery monitoring working, and I’m working out a few bugs with the I2C communication.
I’ve tested with an eMMC CM4, and I successfully flashed firmware over USB
The CM4 antenna connector is compatible with the internal antenna on the PSP case
I’ll probably film a video soon, and go over Prototype 1 thoroughly.
Prototype 2 – ordered February 21, 2021:
First test of DPI mode 7 (RGB888 reduced to RGB777 to save some pins)
Better PCB layout and pin usage
Includes connector for headphone/MicroSD board
Includes an expansion header for an Ethernet board (just testing this in case I use a non-wifi CM4, since every CM4 has gigabit ethernet)
Testing a new audio header that should be compatible with the original PSP speaker cable
Prototype 3 and 4 – ordered March 11, 2021:
Better circuit layout for the boost IC to reduce switching noise
New audio filter layout to decrease bass on the PSP speakers
Full Redesign Prototype 1 – ordered October 7, 2021:
Full redesign to include everything from the PSPi Zero and to substitute components that keep going out of stock
Switched to 2.1A synchronous buck charging IC instead of the 1A linear charging TP4056 to reduce the amount of heat generated during charging.
Switching from RGB777 to full 24-bit RBG888 for the display, giving the best quality possible.
This one is a major test of JLCPCB’s assembly capabilities
Full Redesign Prototype 2 – Ordered May 23, 2023:
Redesigned power circuit that fixes some problems that occurred due to the way the CM4 powers on and off.
Finished the basic design for the carrier board that interfaces with the CM4.
Flipped the Pi Zero connector so that pre-soldered headers will work with the board.