Please give feedback on how difficult this guide is to follow. Let me know any areas that are confusing or that don’t give enough info.
This project is now complete and I’m starting Version 1000.3. I’m going to tweak this guide a bit to make it easier to follow, but for the most part it’s done. I’ve posted a video of PSPi Version 2 in action. Please continue to ask questions as needed. I’m happy to answer them.
Welcome to the PSPi Version 2 build page. Another dead PSP is being given a second chance using the $5 Pi Zero. The main goal with this project is to spend as little as possible on the components. When possible, I will create instead of purchase, and I’m making tutorials along the way that should be helpful for any Pi project. This one will have all the same features as Version 1000.1 and even a few more. I’m documenting every part of it with photos, and if anyone wants more information on any part of it I’m happy to respond to questions.
For those making your own version of the PSPi or a similar project, head over here to the PSPi Forum and create a topic if you have questions or need help.
For those that want to build your own, here are the components used in the build.
IRF7319 Dual Mosfet on eBay or Amazon
LM393 Voltage Comparator on eBay or Amazon
Lithium Charge Controller and Power Board on eBay or Banggood or otherMod.com
4.3″ Composite LCD on eBay or Amazon or otherMod.com
24-Pin FPC Connector on eBay or Amazon
24-Pin FPC Cables on eBay or Amazon
10-Pin FPC Connector on eBay or Amazon
10-Pin FPC Cables on eBay
Lithium Batteries on eBay or Amazon or otherMod.com
Audio Amplifier on eBay or Amazon or otherMod.com
BAT54C Dual Diode on eBay or Amazon
26 AWG Wire 6-Color Set on Amazon
USB Charging Cable on Amazon or eBay
MiniUSB to USB Adapter on eBay or otherMod.com
Mini USB Female Connector on otherMod.com
8GB MicroSD Class 10 SD Card with Adapter on Amazon
Pi Zero Kit with Class 10 8GB MicroSD and Power Supply on eBay or Adafruit
Miscellaneous Resistors and Capacitors
Features and Details:
4.3″ 480×272 Composite LCD
Completely gutted, and only the original button boards are used
GPIO audio output with Class D stereo amplifier
Working miniUSB port on top
The Sony Memory Card slot converted to microSD and wired to the Pi Zero
Original power jack is used to charge
Momentary press of power button turns the console on and off. Pushing the button when the Pi is on shuts the OS down and powers the system off.
Controls wired directly to GPIO pins
2 cell phone batteries in parallel for extended play time
Low battery warning LED and charging LEDs
The teardown process is straightforward. Some original internal parts will be reused.
Power Supply and Lithium Charge Controller Board Install
The power supply board handles 5v power in, 5v power out, and 3.7v lithium battery charging. The USB connectors have to be removed so everything will fit. Also, some case plastics need to be ground down to make room. For more information on how this board works, check out the lithium power supply tutorial.
I reused the headphone jack from the old PSP board. A rework machine does the removal job well. The headphone jack will not be functional in this version. It is not wired in a way that allows the speakers to be disconnected, so it has little purpose right now. This might be something added to the next version. Here is the jack hot glued back in its original location.
Running the yellow/black battery and the power input wires and the red/black power output wire. The green/black wires to the headphone jack are unnecessary and will not be used on this build. A ground wire should be soldered from the power output as shown in the last picture. This will be used for the audio amplifier.
Audio and MicroSD Wiring
SD to MicroSD adapter are glued into position and audio amp is set in place. Adding solder to the SD adapter in prep for soldering wires. Soldering wires to the amplifier. The green wires are the left and right positive outputs going to the speakers. The negative wires from the speakers are joined together and soldered directly to the GND on the output of the power board, and the GND is also connected to the GND for the power and speaker inputs on the amplifier. The audio circuit is explained here. The additional audio filter components will be added later.
It’s time to start wiring the MicroSD adapter. I made the wires long because I hadn’t decided which direction I was mounting the Pi Zero. I ran hot glue along the wires to keep them from moving. Notice that one pin on the SD card is not used. Different colors were used so it will be easier to solder to the Pi later. For more information on how the microSD wiring works, check out the external microSD guide here.
Test fitting the LCD bracket. Everything fits nicely and the wires are routed properly. The bracket has to be modified to make room for the LCD driver and for later modification of the joystick
Modifying the plastics to make room for the new components
Here is the new FPC cable and the cable original to the PSP. The blue rigid plastic needs to be removed from the new 24-pin FPC cable. I could have ordered an FPC 24 extender for $5-10, but this $0.10 cable does the trick by sandwiching the contacts together and it takes up no extra space. I had to be careful not to bend the contacts on the new cable. I did this by pushing the new cable into the connector first, then pushing the PSP one in next. The connector is hard to close, and it squishes them together really hard. I know you’re asking why this cable is being installed. The explanation is later in the guide.
LCD and LCD Driver Installation
I’m about to mount the LCD bracket. It won’t sit correctly on the left side because the motherboard is no longer installed. It will crush the left trigger and keep it from working. It needs two spacers for the screws that are the thickness of the motherboard. So I cut out the small section of the dead board and used them.
Installing the other two LCD screws that are in the battery compartment
LCD installation and LCD driver. Make sure the LCD driver has insulation on the bottom, otherwise it’ll short out on the bracket. I used a piece of plastic cut to the size of the board.
Mini USB connector installation. Not being soldered yet.
Test fitting and doing a quick test of the Pi and LCD before I start soldering.
Soldering the MicroSD Port
Soldering the MicroSD pins to the pads on the Pi Zero and soldering the ground wire from the power board to a ground pad on the Pi. Again, for more information on how the microSD wiring works, check out the external microSD guide here.
Battery Disassembly and Installation
This is a good time to do one more test to make sure everything still works after soldering the SD card wires.
FPC Cable Soldering
This next part is what separates the men from the boys. So we have a 24-pin FPC connector with contacts for the power/charge LED’s, power switches, and control buttons. We need a way to connect that to the Pi. Here is my solution.
Yes, you’re seeing that right. I’m using scissors to separate the individual wires on the cable, but a sharp knife works well too. I’m then soldering them directly to the GPIO on the Pi. There are multiple ground wires and I’m waiting until all other wires are soldered before soldering them. I’m going to bundle them together and solder them all at once. A more detailed description of this process is shown on the PSP FPC Guide.
So far I have the right side controls (circle, triangle, square, x) along with start and select soldered in place. The 5v LED power wire soldered up is also soldered up and the ground wire for the green power LED is going to be soldered to GND along with all the other GND wires. The LED’s can be powered directly by 5v because there are resistors already on the original PSP board (it’s like Sony knew I would want to do this)
Here are three important photos you will need to solder the GPIO wires in place. It will be your choice on which GPIO pins to use, and your software needs to be configured to look for input on each GPIO pin. Most of the GPIO pins are used up by the controls.
The R Trigger is the far right pin on the FPC connector in the photo above. The GPIO pinout is modified to match the orientation of the Pi Zero when its flipped upside down and mounted the way I have it.
Now it’s time to start on the left side controls. This is going to happen exactly how the right side controls did, except with a 10-pin FPC cable instead of a 24-pin. Once the wires are sandwiched together, the white FPC cable is routed to the motherboard compartment and the control board is clipped into position. Again, the wires must be separated and soldered individually.
Soft Power On/Off Circuit
For a detailed explanation, check out the power circuit tutorial.
Now that the controls are soldered it’s time for a power-on test. It is also a good time to build and test the power-on/power-off circuit. It’s a dual-mosfet (positive and negative) circuit. Pushing a momentary switch turns the power on.
This starts with a dual diode. I chose the BAT54C because it has the right characteristics. Basically it is 2 diodes with the cathodes connected together. This is needed because the power switch has two functions…it powers on the Pi by supplying GND to the P-channel mosfet gate, and it powers off the Pi using GPIO. The dual diode keeps the two functions from affecting each other. You don’t have to use a single component here. Soldering two separate diodes works just as well.
Here is the dual diode component soldered to the GPIO pin and to the power switch. The switch connects to ground when pushed. Before I build the full power circuit, I’m routing the wires a little better.
And here is what makes all the magic happen, the IRF7319 dual mosfet. The left half is an N-channel mosfet and the right side is a P-channel mosfet. Earlier in the guide the GND wire from the lithium power supply got soldered directly to a pad on the Pi. The positive side is the part that will get switched on and off.
The circuit works like this:
The +5v wire runs from the power supple to the input on the P-channel mosfet, and the output from the mosfet runs to the Pi. Power is only supplied when the gate on the mosfet is connected to ground. When the power button is pushed, the ground connects to the gate of the P-channel mosfet and power is supplied to the Pi.
The problem is that this will only keep the system powered as long as the button is held. This is where the other half of the component comes in… the N-channel mosfet. This mosfet works opposite of the P-channel, and has a negative input and output with a positive gate. Current only flows when the gate is positive. The output is connected to the gate on the P-channel mosfet.
Here is the output of the N-channel connected to the gate on the P-channel. The two pins on the top-right side are N-channel outputs and are internally connected together. It doesn’t matter which one you use. The bottom-left is the P-channel gate.
It’s very hard to see below, but a 300k ohm resistor is soldered between the gate and +5v input. This keeps the gate at +5v normally and keeps the mosfet from turning on due to electrical fields nearby. You don’t have to use an SMD resistor. I used one for the small size.
And now the +5v output is wired to the Pi power input. If the resistor wasn’t soldered right now, there would be a 50/50 chance that the Pi would have powered on when I soldered it in place. The resistor keeps that from happening.
Now for the rest of the circuit. As it sits right now, pushing the power button turns the Pi on, but as soon as the button is released the resistor will bring the gate back to +5v and the power will be cut off. It needs something to keep the gate connected to ground. The N-channel mosfet performs this task.
The ground wire is soldered from the ground on the Pi to the top-left pin on the component, which is the input for the N-channel mosfet. The output from the N-channel is already run to the gate of the P-channel, and now we need something positive to turn on the N-channel. The TXD pin on the Pi is perfect for this because it goes positive as soon as the OS starts booting. Not only that, but is switches to ground when the “sudo poweroff” command is run. This means that the Pi is completely powered off when the shutdown command is run. In this configuration, the power button needs to be held for about two seconds for the Pi to stay powered on.
There is one more component to solder in place to complete this. We need one more 300k ohm resistor and it goes between the N-mosfet gate and GND. This resistor drops the voltage of the gate down to zero as soon as the Pi shuts down and kills power to the rest of the circuit. The Pi will power off and no power will be drawn.
Now the system can be fully powered off by running the shutdown command. Pressing start in EmulationStation and selecting Quit and Shutdown will accomplish this, but who wants to do all that? A button is easier. The same button that turns it on also turning it off is much easier.
The other end of the dual diode is soldered to a GPIO pin, and when software detects falling voltage (which is what happens when the power button is pressed) the software issues the shutdown command. This allows the system to be shut off at the push of a switch, no matter what is running.
So that’s all there is to the power on/off circuit. I used surface mount components to save space, but standard ones will work fine.
Soldering the USB Port
A MiniUSB port has 5 pins, but only 4 are used. Here is the +5v wire being soldered from the LCD controller to the +5v pin on the port and the ground wire being soldered in the same way.
The first USB data pad is PP22 on the Pi Zero, and it is D+ and gets soldered to this pin on the USB connector
The other pad is PP23, and is D- and gets soldered right next to the other one on the Pi
Now for the +5v, GND, and composite video wires coming from the Pi. I should have done this before soldering the data cables. Better late than never.
One more ground wire is getting soldered to the LCD driver. It’s about to be used to solder all the ground wires from the FPC 24 cable. Until now, they have just been tied together. This is being done now because after the next step there is no going back. All the ground wires from both FPC cables join together now and are soldered to the ground wire coming from the LCD driver.
And the point of no return. This hot glue secures everything in place, keeping the USB port from moving when a cable is plugged in. Make sure you test the USB before doing this, since it’ll be really hard to fix those wires once the area is filled with glue.
The next step is the audio filter. The guide is complete and available here.
150 ohm resistors are soldered between the ground and the L and R audio inputs. Then, the 10uF tantalum capacitors are soldered to the L and R inputs. Tantalum capacitors were chosen because they sound much better than ceramic. The green wires come from GPIO pins 13 and 18 and solder to the capacitors. This completes the High Pass Filter. The Low Pass Filter is soldered to the amplifier output, and consists of a 270 ohm resistor soldered in line and a 33nF capacitor connected between the positive audio outputs and GND.
Low Battery Circuit
We are nearing completion with only a few more pieces to install. The low battery warning LED is next. At it’s heart is the LM393 voltage comparator, which compares two voltages and switches an output to either 5v or GND depending on which input voltage is higher. The function is explained in detail on the Low Battery Warning Circuit tutorial.
In this application we need a way of knowing the lithium battery is close to being depleted, so we compare the lithium voltage to a stable voltage.
This image shows the discharge curve of a lithium battery. When it reaches 3.6v it’s at about 20% capacity, so that’s a good voltage for a warning light. For this circuit to work, we need to generate a stable 3.6v so we have something to compare against the battery voltage. There are many ways of doing this, and in this situation I perfer a buck converter.
The buck converter is glued into place and the 5v and ground wires are soldered to the inputs. The variable resistor is adjusted until the output reaches 3.6v, or whatever you prefer your low battery warning voltage to be. The LM393 is then set on top of the buck converter to prepare for soldering. If you look at the 4th pic, you can see it glued into place.
I made a few changes to the low battery circuit. The LED now lights when the Pi is off and the charger is connected, giving an indication of charge status. Check out the changes here.
Plugged in and fully charged
So I’m calling the hardware side complete. I was going to add the joystick circuit, but I’ve chosen to add it to the next PSPi. I’ve got some changes to make to the software on this, then I’ll start on the next one.