Have you ever wanted a portable computer you can take with you? This is the easiest way to build your own. For those of you who do not know what a Raspberry Pi is, it is a complete computer about the size of deck of cards that can run many different kinds of Linux. This portable computer will be complete with a screen, keyboard, wifi, and a battery. This is just to show how to make the components work on battery, this indestructible does not have instructions for building a case. There are a lot of interesting ideas for cases and I did want to limit anyone's options. I tried to find the easiest way of making a portable all in one battery powered computer.
For this project you will need to be comfortable doing electrical soldering and desoldering; if you are have not done electrical soldering before, there are many tutorials online.
Parts required
- Raspberry Pi
- 3.5 inch screen
- Mini WiFi keyboard.
- Battery pack (need one wired to deans, and between 7 volts and 24 volts)
- 5 volt resistor
- 16 Gauge wire (Red and White)
- Single AV cable (at least one end needs to be male) (Optional, see step 4)
- Electrical solder
- SD card
- Micro USB cable
- Heat shrink
These instructions were designed for these parts, they can be interchanged but you may need to be adjusted.
Tools
- Soldering gun
- Small Phillips head Screwdriver
- Wire Strippers/cutters
Created May 29, 2014
Step 1: Figuring out the layout
Before doing any work in this project you need to take the screen, raspberry pi, battery, and 5 volt regulator and figure out where you will want them in the case you build. Keep in mind you will need space for the wires, SD card, and the micro USB cable going from the resister to the Raspberry Pi. Use this as a reference for length of wires throughout the project. The picture above shows the layout I used.
Step 2: Preparing the Screen
Materials needed for this step.
- Screen
- Small Phillips screwdriver
- Wire cutters
- Soldering Iron (optional)
In this step you are preparing the screen to be wired in later, the screen is in many different steps so it is important to get it ready first.
1.First turn the screen so the back side is up. There are two screws on the back as shown in figure 1 (note one screw is under a sticker).
2.Now using the wire cutter to cut the wire prior to the three point split, make sure you have enough length to reach the battery and the Raspberry Pi as shown in figure 2.
3.Pull the back casing off of the screen.
4.Strip the large black wire casing, this should expose 4 smaller wires as seen in figure 3, depending on the length you may be able to pull it off, but in some cases you will have to use the wire strippers. (Make sure if you use the wire strippers to go slowly and make sure you do not cut the wires inside)
5. The white wire is not needed so you can choose to ignore it, cut it, or desolder it.
Step 3: Wiring the Battery to the 5v regulator
Materials needed for this step
- Deans Connector
- 5 volt resistor
- 16 gauge wire
- Electrical Solder
- Soldering iron/gun
- Small Phillips screwdriver
In this step you will be wiring the 5 volt regulator to the deans connector that the battery will plug into. The 5 volt regulation is very important because the only made to run on 5 volts.
1. Take 1 red and 1 white 16 gauge wire and cut it to length, make sure it is long enough to reach the battery and the 5 volt regulator.
2. Use the 16 gauge hole in the wire strippers to cut 1/4 inch of the wire cover on each end of both wires.
3. Solder the red wire to positive and white wire to negative. If you are unsure which one is + and which one is - refer to figure 1.
4. Take the 5 volt regular and and unscrew the two screws until the head of the screws are just about the top of the plastic. You can see where the screw are located in figure 3.
5. Take the deans connector with the two wires connected and place the wire into its respective terminal on the 5 volt regulator, as shown if figure 4. The positive and negative ports are labeled on the bottom of the resistor.
Warning: It is very important you do not you mix up + and -. This could lead to short circuits and even fire.
Step 4: Wiring the screen
Materials needed for this step
- Wire cutters
- Screen
- Soldering iron
- Solder
- AV cable (optional, seen step 4 to see if needed)
- Raspberry Pi
1.Use the wire cutters to strip the casing of red, black, and yellow cable attached to the screen. Most wire strippers do not go that small of a gauge, this means you will need to use the cutters instead. Remember to cut slow.
2. Solder the red wire to the same deans connector as you did for the 5 volt regulator.
3. Solder the black wire to the same deans connector as you did for the 5 volt regulator.
Use figure 1 for reference to steps 2, and 3
4. for the next steps you have two options
Option A. You can desolder the AV input on the raspberry pi and solder the yellow wire directly to the board. Option A takes longer and is more difficult, but in the end takes up less space.
Option B. You can solder a male AV cable onto the yellow wire and plug it into the AV input. Option B is faster and easier, but takes up a lot more space.
Before wiring in the display and power to the Raspberry Pi install the operating system (OS) onto the SD card.This is important because the install of the OS can fail if the battery dies.
Option A.
- Desolder the 3 mounts on the under side of the Raspberry Pi. Use figure 2 as reference.
- After the AV mount is desoldered and removed solder the yellow cable coming from the screen onto the top right AV mount that was desoldered. Use figure 3 for reference.
Option B.
- Take the AV cable and cut it to length, it will need to be long enough to plug into the Raspberry Pi as well as touching the yellow wire from the screen.
- Use your wire strippers to strip the AV cable 1/4 inch.
- Solder the male AV cable and the yellow cable coming of the screen.(remember to put heat shrink over the wire before you start soldering)
Note: When cutting the AV cable you may notice wire surrounding the yellow cable inside. Those wires are the ground wires. The screen I am using shares a common ground with power, so these wires are not needed.
Step 5: Resizing the Micro USB cable
Materials needed
- Micro USB cable
- Wire Stripper/cutter
- Soldering iron
- Solder
1. Cut your micro USB cable to length, remember there are two sides you need to cut each side to 1/2 the length you need. this cable will need to go from the 5 volt regulator to the Raspberry Pi.
2. Use the wire Stripper to strip the outer casing of the USB. It should look like figure 1. Remember to leave room for the heat shrink, give it a decent amount of room between it and where you're soldering, if they are to close it will shrink when soldering.
3. Remove 1/4 inch of casing off each smaller wire within, do this to both sides.
4. Solder the the matching colors together. (Do not forget about the shrink wrap)
5. Depending of the form factor necessary, you may need to remove the casing around each end, as you can see in both picture above.
Step 6: Assembly
It is important to remember this step will vary based on your case and arrangement.
- Make sure everything fits in the original arrangement wanted.
- Plug the Micro USB cable into the raspberry pi and the 5 volt regulator
- Plug the Deans connector into the battery
- Make sure everything is operational
Step 7: Troubleshooting
- If you plug the battery in and you do not see a red led light on the Raspberry Pi this means the Pi is not getting power. Check your solders, as well as make sure your micro USB cable in firmly attached at both the Raspberry Pi and the 5 volt resister
- If the screen is not working, check the connection between the screen and the screen driver board as well as the connection to the Pi and the power solders. It is important to note that the screen will not turn on without video input.
- If the screen is white, it means that when the Raspberry Pi turned on the screen had no power, but got power later. This means you have a loose connection. Most likely the ribbon cable connecting the screen to the driver board, but could also be the AV cable plugged in or soldered to the Raspberry Pi.
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