Introduction: Pocket-Sized Linux Computer: Pi-Micro
Have you ever wanted to make a computer that could fit in your hand? One that was a full-fledged laptop, but tiny? Me too, so I built this little laptop, which I call the Pi-Micro. This is the third version of the Pi-Micro, almost a year in the making, and I felt that it was polished enough to share. The Pi-Micro runs a full linux operating system, and has the ability to browse the web, create and edit documents, use the terminal, create custom programming scripts, and play games. As far as I know, it is the smallest computer built using a Raspberry Pi that also has a full keyboard. It is built around the Raspberry Pi Zero W, which has WiFi and Bluetooth built in.
512 MB RAM
Built in WiFi and Bluetooth
1000mAh Li-ion Internal Battery
16GB Internal Storage
Full QWERTY Keyboard
Only 108mm x 19.5mm x 70mm (Or 4.25" x .75" x 2.75")
Step 1: The History of Pi-Micro
This is an optional part, so if you want start reading the instructions, skip to step two.
This laptop has been something that I have worked on for over a year, and during that year I went through a lot of different designs and prototypes, as you can see in the pictures above. My first two designs were rather top-heavy, and both hingeing mechanisms were inadequate for the weight of the screen/motherboard combo.
V1.0 (Black) My first version of the Pi-Micro was made on May 6, 2017. It used 3D Printed hinges, which were too loose, and didn't allow the screen to stand on its own. It had a design in which the keyboard was built into the case, which I like, but it was very thick and bulky. The edges on the top and bottom of the case were also not rounded, which gave it a cheap look.
V2.0 (Blue) My second version of the Pi-Micro was made around October 2017. I tried to fix the hingeing problems by using super small brass hinges, but they were also too loose. In this version, I made it look much nicer by rounding all of the edges, and by making the cutouts for the Raspberry Pi in the 3D modeling program instead of with my soldering iron. One unique thing about this version was that I made it so that the keyboard, which I attached the hinges to, could easily be detached from the top half. However, I ended up disliking how it looked, and thought that it did not look enough like a laptop.
Step 2: Project Overview, and a Brief Warning/Disclaimer
The best projects are never easy. I have been working on this computer for over a year, and have gone through several versions to get to the finished product it is now. This project requires a lot of difficult soldering/desoldering, and a basic understanding of Linux and Raspberry Pi.
DISCLAIMER: (Sorry, but my father is an insurance agent :)
This project involves things that can cut you, burn you, and shock you if you are careless. I have actually had all of those things happen to me, all because I was careless. I am not responsible in any way if you injure yourself, or anything. Always wear adequate protection, don't connect the red and black wires, and definitely don't puncture the battery. BE CAREFUL!
Step 3: Parts/Tools Necessary
For this project we will need a bunch of parts, I have attempted to add a link to all of the parts in addition to their names.
1. Raspberry Pi Zero W Link $10
2. Waveshare 3.5" Touchscreem Display Link $25 (I used a different one because it was free, but this one is much easier to set up)
3. 3D Printed Case $15
4. "Solar Juice" Power Bank Link $20
5. Mini Bluetooth Keyboard Link $12
6. Micro SD Card Link $12
7. Female USB Jack Link $1
8. Two Sewing Needles Link $1
9. Misc. Wires, Screws, and Glue
Total (Including Tax + Shipping) : ~$120
The total cost comes out to about $120 if you have to buy everything, but it would be less if you have some of the items needed.
Step 4: 3D Print the Case
Okay, now that the other stuff is out of the way we can begin working on the computer. The first thing to do to build this awesome little computer is to 3D print the case, or, if you do not have a 3D printer, order it. I have attached the files at the end of this step, and they should be printable on most 3D printers.
For the people without a 3D Printer, I would recommend using an online printing service such as Shapeways or i.Materialise to print the case.
For 3D printing people, my print settings are here:
Filament: ESUN PLA+
Layer Height: 0.2MM
Step 5: Disassemble the Power Bank
I apologize that I do not have any pictures of the disassembly, but it is pretty straight-forward, and the instructions make more sense when you have the power bank in front of you.
The objective of the disassembly is to get a battery/charger combo that is thin, has a power switch, and has a 5v output.
Step 1. Remove the screws from the case, and remove the innards from the aluminum shell.
Step 2. Cut the wires from the solar panel to the controller board.
Step 3. Disconnect the battery, and then reconnect it with two 3" long wires in between it and the controller board.
Step 3. This is the hardest part. Desolder the USB port, and solder wires to the positive and negative outputs of the controller board.
Step 4. DONE! Now you have a nice little battery that can be charged from a USB, and can safely power the computer.
Step 6: Prepare the Screen Assembly
IMPORTANT: This step is based upon the Waveshare 3.5" display. If you are using a different one, change the pins that you solder the wires to to fit your display specifications.
If you need any more info on the display check out this link: INFO
1. Using whatever method you want, desolder the headers from the Touchscreen. Personally, I found it easiest to use flush cutters to clip it off, and then to use my soldering iron to remove the bottom halves of the pins individually from the board.
2. Solder wires to pins 1, 2, 6, 11, 18, 19, 21, 22, 23, 24, and 26.
3. Label all of the wires, so that you can tell which one is which without seeing the back of the display. I included a couple of photos of my labeling system.
4. Double-check the labeling.
4. Drill holes in both 3D printed display parts, so that they can be screwed together.
6. Triple-check the labeling. Trust me, it'll save A LOT of frustration.
5. Place the screen inside of the parts, and screw it together.
Step 7: Solder the USB Jack to the Raspberry Pi
Everyone knows that computers need USB ports (except the people at Apple apparently), so we are going to install one in the bottom right half of our computer.
1. First, we'll start by using wire cutters to clip the small tabs on either side of the USB jack (NOT any of the four pins), because we won't need them to hold the USB in place.
2. Next, bend the four pins down at a 90 degree angle, so that they stick out the back, and the jack has nothing sticking out the bottom.
3. Now solder a wire to each pin, making sure they are long enough to reach from one side of the case to the other, and then insulate the terminals with heat shrink tubing if you want.
TIP: Use different colors of wire; it helps keep track of which is which when you are connecting them to the Pi.
4. Using the circuit diagram above, solder the wires to the pads of the Pi.
Step 8: Solder the Battery to the Raspberry Pi
1. Solder the red wire from the power bank 5V output the the Pi 5V pin.
2. Solder the black wire from the power bank GND output to the Pi GND pin.
Step 9: Solder the Screen to the Raspberry Pi
This is a tricky step, so go carefully. I went through three touchscreens because I was careless, and caused myself a lot of frustration.
1. Shorten your wires, if applicable. If your wires are too long, they will bunch up inside the bottom case and make it hard to close. Try to measure the distance that each wire will need, and approximately cut them so that when the display and the bottom half are laying out, there will be a 2CM gap between the edge of the bottom case and the edge of the display.
2. Connect the labeled wires to their corresponding pins on the Pi. Before you do it though, think long and hard to make sure that you aren't doing it backwards.
Step 10: Software...
For this build you will need a micro SD card that is at least 8GB big, but the size you use will determine the size of your Pi-Micro's internal storage.
This is an important step, because it also helps determine whether the screen and battery have been connected correctly.
1. Format your Micro SD to FAT32
2. Download the pre-made image for the Waveshare display here: https://www.waveshare.com/wiki/3.5inch_RPi_LCD_(A)
3. Using Etcher, burn the image onto the Micro SD.
4. Insert the card into the Pi, turn the battery on, and pray.
5. If you made no mistakes, it should all work. If it doesn't, double check all of the solder joints and wiring. Good luck!
6. Pair your bluetooth keyboard to the Pi. This means that later we will not have to access the pairing button on the keyboard, and that it will automatically connect on every boot.
Step 11: Slim the Keyboard Down, and Solder It to the Raspberry Pi
For the keyboard of the Pi-Micro we'll be using a mini bluetooth keyboard with the battery removed, and soldered to the Pi instead. This is a
1. Split the keyboard case open. I found that the easiest way to do this was to bend the keyboard until a crack appeared between the top and bottom halves of the case, and then to use a flathead screwdriver to pry it apart.
2. Remove the micro-USB charging port. This can be done easily with a soldering iron by heating the area directly behind the port, which will easily slide off with the solder melted.
3. Desolder the battery. Then, remove it.
4. Solder two wires to the terminals where the battery used to connect to.
5. Turn it on. (It won't do anything now, but when we connect it to the Pi, it ensures that it will turn on at the same time.)
6. Solder the wire from the positive battery terminal to the 3.3V pin on the Pi
7. Solder the wire from the negative battery terminal to any of the GND pins on the Pi.
Step 12: Putting It All Together
Now the most nerve-racking part: the final assembly. For the hingeing mechanism, I decided to use needles as axles, which is an idea I got from one of my other recent projects.
TIP: If something in the case is preventing it from sitting flush, don't try to force it. It's always better to shuffle stuff inside the case than to try to squeeze it.
1. Make sure everything fits. Put it all in the case, put the lid on the bottom half, and make sure that it sits flush. If not, it is much easier to fix BEFORE everything is glued.
2. Hot Glue everything down (EXCEPT THE BATTERY, WHICH COULD EXPLODE). This ensures that nothing rattles when you shake the completed computer, and that the USB and charging ports don't get pushed into the computer when you attempt to use them.
3. Now that everything is secure, put the lid on the bottom half and use whatever screws you have to secure it. You may have to pre-drill the holes, which I didn't put into the design because of the varying thicknesses of screws that can be used.
4. Put the display on the bottom half. Make sure that it can fit over the bottom hinges, and that it can rotate.
5. Install the needles. I recommend using the largest diameter needles that you can, because it will make the hinges stiffer. You also will probably need to use the end of a block of wood or something to push them in.
6. If you want, use your soldering iron to melt the plastic over the ends of the needles, so they don't slide out.
7. If necessary, go around the edges of the bottom and lid of the lower half, and use a soldering iron to weld any places where there is a gap.
Step 13: Enjoy!
DONE! Show your friends, who will be in awe of your electronics wizardry. I hope that you enjoyed making this project! If you liked it, please vote for this Instructable so I can share more cool projects! Thanks for reading.