The Pi Tablet

by Kirand1

37K34024

Intro: The Pi Tablet

Hello fellow makers, following on from last year when I made a Pi-Laptop, I will be making Pi Tablet (see the theme here!). Well I say its a Pi tablet but the main goal was to make a tablet which can house the vast majority of single board computers and each can be changed really easily such as the Raspberry pi etc. This project is not too hard to build and is quite cheap so I hope you enjoy this instructable.

PS: please vote for me in the competition :)

STEP 1: Parts and Tools...

Probably the most important step is the materials and tools needed for this build. Please remember these parts are just a guideline and don't be scared to experiment with other parts and ways of doing the project.

PARTS:

OPTIONAL PARTS:

TOOLS:

  • Adobe illustrator or a equivalent 2D Design tool
  • Laser cutter/ cnc mill / good ol'fashioned saw :)
  • screw drivers
  • pliars
  • soldering iron
  • solder
  • hot glue
  • electrical tape / heat shrink
  • super glue
  • hot glue

STEP 2: Building the Case

For this build, just like my Laptop build, I used a laser cutter but this time I experimented with an online cutting service for the majority of the cuts. I have to give a shoutout to the guys over at Razorlab for the support they gave me. I normally design my cuts on a program called 2D design which is okay apart from the propriety file format and that the majority of industry actually use adobe illustrator. These guys helped me to convert my drawings and make sure they would work properly.

The main reason why I like to laser cut my parts is down to the ease, accuracy and precision that comes with laser cutting. Also not to forget that when using an online service like Razor lab, the price is very reasonable. However using a saw and cutting each part manually can work as well although the final finish if you are using clear perspex like me won't be as good.I have provided the drawings in both a dxf and a dtd and they are all in scale if you want to try it out yourself.

After the parts were cut, I did do a test fit of the case to make sure everything fit properly but I didn't glue the case until the other parts were made.

Case.dtd (for 2d Design)

Case.dxf (for everything else)

If you want me to add another file format e.g svg just ask

STEP 3: The Power Supply

The easiest way to do this is to make use of those cheap usb backup power packs that you can get off amazon for under £20. However being the ambitious person I am I decided to make my own...

I wouldn't recommend this for people who are not experienced or skilled in the art of not blowing up a lipo and general soldering techniques.

For my tablet I decided not to use 18650 li-ion cells and use a 2s 5000 mah battery from hobby king. This is because the battery from hobby king fits perfectly in my case and is a whole lot lighter when compared to an equivalent setup of 18650 li-ion cells.

Most single board computers like the Raspberry pi require usb to power them or 5v at around 1-2A. The battery from hobby king was a 2s meaning it was 7.4v and only 5000 mah so to increase capacity and half the voltage I changed the cell arrangement to be wired in parallel. If you are going to try this make sure when modifying the battery that you don't short the battery or overheat it.

NB:Modifying lipos is like playing with bombs.

After the modifications are complete the new battery will now be a 10000mah battery running at roughly 3.7v. However the Raspberry pi won't take a varying 3.7v input so I used a cheapish charging circuit which does a few things. Firstly it allows for the battery to be charged with a micro usb plug and secondly it takes the varying voltage from the battery and uses an inline regulator to create a constant 5V supply.

Finally I soldered on an opposing battery connector onto the charging circuit while also soldering on the negative lead of a micro usb cable to the negative output on the charging circuit. The positive output will need to be soldered onto the common pin on switch and the positive lead of the usb cable will need to be soldered onto the other side of the switch. Remember to allow enough slack in the wires so the components can be fitted easily in the case.

STEP 4: IO

USB Ports

To allow access to the usb ports when the tablet is assembled, I used a usb hub which allowed me to have 3 external usb ports and 1 internal port. First disassemble the usb hub and discard of the case. Next I add some hot glue to where the wires are soldered to firstly provide some strain relief during assembly but also to insulate them. Finally glue on the plastic cover to the front of usb hub with super glue so it can be easily slotted into the case.

3mm Headphone port

This part is really easy. Take a 3mm headphone cable, strip one end to reveal either two cables, or a single cable with shielding. If your cable has two smaller cables inside then find which cable is positive(normally red) and negative(normally black or blue ) and solder to the corresponding pins on the female plug. If your wire has 1 wire in the middle with shielding, the shielding is negative and the middle wire is positive. So solder the shielding to the negative pin of the female jack and solder the centre wire to the positive plug. I have attached some diagrams to show the polarity of the plug. Again I test fitted and tested the audio before installing it.

STEP 5: HDMI Soldering

This is probably the most difficult soldering part of the whole project. I would recommend trying to find a flexible thin HDMI cable but I found that the majority of HDMI cables have a bulky plastic shielding in their plugs which are not very useful for a tablet. I definitely spent at least an hour on it if not more. I have attached a diagram which should show you the basics and here's a link to a video which I made a while back for my laptop, it gives the general idea but just ignore the part about threading wires through a hole.

First off you want to tin your HDMI plugs. The HDMI plugs already have solder pads but tinning them is recommended as it makes soldering the wires much easier. Next you want to get thin wires. I would recommend IDE cable as it can be easily bent and is thin so fits well in the case plus you can recycle the wires in that old beast of a computer from the 1900's which still uses IDE drives (heheheh...) . Cut two strips of the IDE cable, one with 10 wires, and another with 9. Cut the cable down to length so it fits well in the case and strip of the insulation at both ends to reveal the bare copper wire inside. Solder one end of the IDE cable to the first HDMI plug, twist the cable upside down, and solder the other end. Repeat this for the other side for the HDMI plug and test it out. If you get no signal first check the connection and then that you have the wires in the correct orientation.

STEP 6: The Screen

First thing to sort out is the power for the screen. The screen requires a micro usb cable which not only powers the screen but also drives the touch part of the screen. Therefore the screen needs to be powered off the raspi usb port. A thin micro usb cable is needed but as I didn't have one available, I made one from a bare micro usb port, a bare usb port and some wire but you could strip off the insulation carefully of an existing cable.

The case I made was specifically designed for my screen so I included the mounting points which meant the screen was held well. I installed the screen in the top part of the case to make it easier when the whole tablet was assembled. I made sure that the bottom piece of the case could be removed easily so that I could replace the screen if need be.

STEP 7: Case and Assembly

The top half of the case is where the screen sits and is also where the machine screws will be fitted to fasten the whole case together. For the bottom half, I started from the bottom up. First the parts are test fitted on a jig using the 4 machine bolts to make sure the parts fit well. Next stage by stage, each layer is glued using a few drops of super glue and every layer is checked so that the case is square.I didn't glue the middle layers so that I can easily open up the case if I want to change out the board or change the battery etc.

To mount the pi, first bolt on mounting screws to the pi, apply a bit of super glue to the heads of the screws and place the pi in the recess in the case, and glue the screws in. This means it is easy to mount and unmount the pi in the case and this method will work with any single board computer as long as it fits in the recess.

Next all the ports are fitted to the case. The usb port simply slots into the topside of the case and is stuck in with a few drops of super glue. The charging port, which is the micro usb port, is glued into the little slot on the side, and finally the audio port is screwed and glued into its corresponding slot.

STEP 8: System Setup and First Startup

I used a fresh install of Raspian for this tablet and I find it works really well. Before starting up the tablet, make sure the battery is charged fully and all the connectors are properly inserted. Insert your SD card and push the power button and it should start up right into the desktop.

Some Notes

  • The touch screen works great on its own for mouse movements but for keyboard I recommend either using the mini wireless keyboard or installing a software keyboard using sudo apt-get install matchbox-keyboard click here for more info.
  • Here is a link to a guide to set up Raspbian.
  • If you enjoyed this instructable please vote for me in the competition as I would greatly appreciate it:)

22 Comments

TheGrayAssassin 7 years ago

I guess you could call it......... the PiPad!!!!

seasteven 5 years ago

i don't get it how about the raspad!

MakerMan234 7 years ago

or the pilet oh wait that sounds like toilet

seasteven 5 years ago

wow ! you and i have just about the same interests am building a re-usable shuttle for stratospheric flights got any ideas and how old are you

Hamids 7 years ago

very neat project , I was wonder if there is any solution in market so we could convert our old laptop to the tablet , I mean using such raspberry board just the prototype hobby solution , but special ready- to- use board to convert old devices could be huge save

JackB64 6 years ago

yes there is ,lcd driver boards can be found on ebay ,you just contact the seller with the model of the back of your lcd , mine is not finished yet but its almost 2 years old ,lol

Kirand1 7 years ago

Would be interesting to try. Maybe have a touch screen available in 3 different sizes where you connect the old device to and a modular case to connect batteries and extra storage. Could be a cool idea!

actuonix 7 years ago

Curious what the total cost was.

Kirand1 7 years ago

Well the casing cost around 40 pounds and was the most expensive part so I would estimate around 80 pounds although I did have the usb port, raspberry pi and those cables lying around. :)

Andrew COC 7 years ago

Can it get games? if so, is there an application just for it?

mindwave 7 years ago

I would also imagine that, if you look up one of the "PI ARCADE" instructables you will find links to the games and emulators that they use. At that point your only challenge (and it could be big) would be controls.

HOWEVER (and this is why I LOVE THIS PROJECT) since this is a real "pc" based tablet and runs a real OS you can find whatever controllers you want and plug it in the USB.

This could truly make this one of the most useful and productive tablet types ever designed.

mindwave 7 years ago

If you dont mind me asking what did the case cost to get made from the folks you linked to? I like to look and wouldnt mind dealing with them, but havent ever done it remotely so just looking for some details.

zThanks

Kirand1 7 years ago

Hey, I don't have the exact figures but I paid around 10 pounds for the actual acrylic (400mmx700mmx3mm) and 20 pounds for the making process. Plus vat and shiping costs etc the price was about 40 pounds which was well below the other competitors and I felt was well worth the money. These guys also have a wide range of materials, excluding any metals and you even have the option of sending your own material in if you needed. As a bonus the customer service people are very helpful and as I mentioned above they helped me to fix many of my drawing files due to the inconsistencies between the software I was familiar with and adobe illustrator.

Hope this helped:)

mindwave 7 years ago

Kirand1,

Thats awesome, just what I was looking for a round ball park figure is what i need.

I always wanted a linux laptop, so i bought a refurb and made one, now for the past couple of years I have hated the windows tablets. Personally I just think that windows NEEDS a bigger screen. However since Linux is my OS at home, having the vailability of a full OS on a tablet, and it being MUCH easier to read and use (hey im 50, I had to get glasses because I read my tablet so much) Linux would be PERFECT!

thnaks

j

ivorcadiramen 7 years ago

Hey, you are 50 and I am 65. I started Electronics as a serious hobby not long ago and was gifted a Raspberry Pi kit recently.

Thank you Kirand for the tip, since I am retired I am looking for reasonable solutions to my issues. Appreciate the post.

More Comments