What is a MAME Cablet and how do we get here?

MAME Cablet - Broken Tablets converted to eBook Readers
Broken Tablets converted to eBook Readers

Well you see, it begins with a tale of woe. My son broke his Android tablet, actually 3 of my kids broke their tablets within 3 weeks of each other also within a month of purchase. Shattered digitisers, fun. Not a bad average and as you may (or may not) know, replacement digitisers are generally as expensive as the tablet itself. The tablets themselves were Chinese Ainol (lawl) tablets and it _really_ wasn’t worth the hassle.

 

The original mod I did was to convert them to eBook readers, the system would boot straight into FBReader which would be controlled by the hardware volume keys. Tablets were now usable again, although we did have to plug in a USB mouse via the OTG connection to change books, remember no digitiser? An acceptable trade off.

The digitisers once removed were replaced by clear 2mm acrylic sheet (e.g. perspex). I measured and the cut a rectangle piece to fit with a Stanley knife and a rule. The rough edges were covered in black contact cut to mimic the digitizer bezel. The kind of contact you may have covered school books with when you were a kid. Worked a treat.

Then the eBook idea wore off; the kids received new tablets for Christmas one year and the old tablet come eBook reader was relegated to the back of the draws. They still worked well enough, it seemed a shame for them to go to waste. One was hooked up to the main TV via HDMI and cycled from a games machine to a XBMC installation, all a bit ‘meh’ basically.

There is always MAME I thought and over the Christmas break of 2014 I set my son and I a project to build the MAME Cablet. My son was interested in a project which contained 3 things, Gaming, Electronics and Woodworking. A MAME cabinet of sorts seemed like a good idea based on the project criteria.

Cabinet

MAME Cablet - Old school drill
Old school drill

So without any real tools (my had been stolen some years earlier) and just some basics that were fairly buggered we set down the path of building the MAME Cablet.

MAME Cablet - Cardboard Mockup
Cardboard Mockup

For giggles we started with a shaped mockup for the MAME Cablet cut and stuck from a Corn Flake box, seemed like and apt use of the item. Wife wasn’t too impressed with the box missing though!

 

We then, just to be thorough moved to Sketchup, building up the model in 3D CAD tweaking and changing some ideas. This was mostly for my son to get some ideas of a decent approach to the project.

 

MAME Cablet - Cabinet Frame
Cabinet Frame

Once we were happy with the shape, we went to see what materials we had available. This was intended to be a $0 exercise. We found some screws, some pieces of lumber and some MDF sheeting that had been given too us for something long forgotten. All the controller parts we had from a previous OzStick controller project. We also had an OTG cable and PSX->USB adapter. Then of course we had the ‘modded’ tablet. Pretty much ready to start.

We measured and we cut, unfortunately I don’t have many details on the sizes anymore, just a few photos. But the configuration! now that is something we can talk about a bit later. Anyway back to the build, some basic stuff really measured, cut, glued and screwed. Found out my jigsaw was stuff and the blade on my circular saw was toast but I digress, it did make me swear and forget to take photos though.

 

MAME Cablet - Bearers Mockup
Bearers Mockup

We did some fairly rudimentary mockups and adjusted as we went. With the tooling issues and a lack of skill we decided this would be the first of two and we began referring to this as the rough cut. In doing so we were free to make changes and just have fun with the project instead of getting bogged down in trying to repair the tools or our mistakes.

At this point we’d also made a few decision as to how the MAME Cablet would come together.

  • The tablet would remain complete and therefore would sit on a shelf which should be accessible by opening the front the cabinet.
  • The controls would be slightly angled forward to provide internal clearance and present them ‘ergonomically’ to the player.
  • It would take up as smaller footprint as we could with the existing parts we had.
  • We would be able to open the back for access to the wiring.

So we continued with the build, had a few basic “unskilled labour” problems but the cabinet itself came together without too many issues. The bezel we cut was complete junk but I can live it on the “rough cut”.

The hole pattern for the controls was done by tracing my sons hand and my hand in the then drilling as close as possible to the median position. Nothing too technical, no templates etc.

Wiring

MAME Cablet - Joystick & Button Clearance
Joystick & Button Clearance

As I have said previously this was a $0 project and we reclaimed a bunch of buttons and a joystick from an OzStick arcade controller. The joystick was I have called “snub nosed” for the form factor. By that I mean we mounted it on blocks under the control panel so the controller looks shorter than it is. There was just enough clearance to do this in the design. The Same is true for the buttons as you can see in the image to the right. The snub nose controller makes a nice touch I think.

Within the OzStick controller we had a previously hacked PS1 digital controller board. We did have to remap/wire the controls for it to make sense to the android tablet without too much configuration on the software side. NB: I am still looking for my notes on the controller mapping.

MAME Cablet - Wired Up
Wired Up

We also added P1/P2 buttons as Start/Select to the site of the cabinet. When hacking the controller we scraped away the carbon on the tracks and soldered direct to the board, once we had a good join we hot glued over the soldered join to give it additional strength. This was then fed into a terminal block so we could adjust our mapping without affecting the soldered joints on the psx controller PCB.

The other side of the terminal block was hooked up to the joystick and buttons. Testing later determined the best configurations for the mapping.

Finally we hooked the PS1 controller up to a compatible PS1->USB adapter these can be picked up for peanuts from Deal Extreme or eBay. The USB side of the adapter was fed into the OTG cable that came with the table. You can see the full wiring setup pictured.

 

Adding the Tablet

MAME Cablet - Tablet and Shelf Installed
Tablet and Shelf Installed

Next we added the tablet, we butchered up a makeshift shelf and bezel to marry up with the tablet. Had a jigsaw remember? Yeh that didn’t work out so well for cutting the bezel so I found out. So I’ll invest in a router at some point (which I did later) and try and use that. Turns out I need more practise at that as well. Tablet was fitted with the OTG cable on the shelf with the bezel and we finally had a chance to test it. We had some wiring issues here and there but it was mostly a success and it looks quite swisho.

A bit more testing, some of the left over acrylic over the bezel, a back door and some “finishing” touches and we haven’t had a need to build a second one although the pieces are cut. It will have to come at some point in time.

 

Software Configuration

Software used for the build was all available via the Play Store

Install both the above, configure AutoStart to boot MAME4droid at start up. Doesn’t really get any more difficult than that.

I set the UI Cancel option to be a combination the buttons connected to the P1 / P2 buttons at the side of the cabinet. This allows you to exit the currently running game and return the menu by pressing them together.

Optional: Install an FTP Server for transferring games

MAME Cablet - Pride of Place
Taking pride of place in the games room

Since Then, Changes to the MAME Cablet

Direct AC Wiring

When we built this, as with all the (except ONDA) tablets we’ve purchased out of China we knew the AC adapter was sketchy when making a connection to charge the tablet. The idea was to then hard wire the AC adapter into the tablet to by pass the dodgy connection. We did this successfully without any real issues to speak.

MAME Cablet - AC Power Soldered
AC Power Soldered
MAME Cablet - AC Power Modded
AC Power Modded Case

Removing the Battery

After a few months with the Direct AC Wiring the battery began to play up and prevent the unit form staying on. Simple solution was to remove the battery all together. This was just a case of de-soldering the two connections on the main board.

MAME Cablet - Battery Connection
Battery Connection
MAME Cablet - Battery Connection Removed
Battery Connection Removed

Final Thoughts

This build from conception to complete was done over 2 days. It was intended to be a simple project with my son. Eventually we will build a prettier one but until that day comes this will serve its purpose. It has now travelled to birthday parties, sleep overs and become quite popular with my son’s friends.

References for MAME Cablet – Android Based MAME Cabinet

None really, I’ve been following MAME for a long, long time but I will include some good links to get you started

MAME 139u1 for MAME Cablet

This is a hard beast to find online, don’t ask me why but thankfully I had a compiled version in my archives. It is made available here for you. You can build a MAME set that is compatible with MAME4droid (139u1) using a tool like CLRMame