Taipan! on the Arduino(s). Part 8 (almost there)!

July 29th, 2012

More progress and things are finally almost complete. I laid everything out inside the hollow book to see that it would all fit. The batteries are made up of two AA cell holders, each holding four Ni-Mh cells.These fit either side of the keypad.The screen is at the top and in the middle is space for the controls and sockets –  a power switch, the RCA video output and a charging socket.

IMG_2636_1 Test fit.

To finish off the keypad I decided to make a brass cover that fits over the front, slightly larger than the aluminium. That would allow me to insert the keypad from the front of the wooden panel and attach it from behind to hold it in place. I cut some brass and carefully cut the holes for the keys. The keys themselves I super-glued to a piece of thin leather. This holds them in place but allows them to move to press the buttons beneath them. I also made a brass bezel for the screen.

IMG_2629_1 Keys on leather.

To age the brass I first cleaned it then left if to soak in apple cider vinegar fumes. You don’t put the brass in the vinegar but instead put the vinegar in a container and sit the brass above it. I used some plastic offcuts as blocks. You then put the lid on the container. The fumes will quickly tarnish the brass and remove the shine.The longer you leave it the more tarnish you get. I left mine overnight since I wanted them really filthy.

IMG_2648_1 Ageing brass in apple cider vinegar.

I also made the main circuit board for the game. This is basically two stand along Arduino circuits and a 5 volt voltage regulator. This board is the same side as the keypad board and sits underneath it. The two are connected via a pin and header. Long bolts go through both boards, the aluminium and the brass cover. Small brass tabs are used to clamp the keypad to the wooden front panel. I actually cut a new front with the grain running vertically since it looked better than my original one.

IMG_2624_1 Circuit board.

The keypad brass bezel is bolted to the aluminium and this is then inserted from the front of the wooden panel. Small brass tabs and nuts then clamp it to the front leaving the four long bolts extending up. The keys are put on next with the buttons fitting into the holes in the aluminium plate. Next the keypad board is slid down over the bolts. Then a spacer over each bolt then finally the main board. Plastic washers and nuts then hold everything in place. Under the middle set of bolts is an additional brass plate that holds the battery packs in place.

IMG_2666_1 Main board mounting.

I later moved the piezo so that the sound could be heard. It was too quiet mounted directly on the board. The 2 pin headers are for power and video output. There is also a header to attach a data LED but I didn’t use this in the final version. I couldn’t find a nice place to put the LED on the front panel.

In the centre of the wooden front I made a small well into which fit the switch and sockets. They need to be recessed of course so the book can close. I actually had to cut the recessed lip on the book deeper to allow room for the screw heads as I didn’t have any countersunk screws to use as I originally intended.

IMG_2638_1 Testing things.

The screen is attached via the two bolts holding the front bezel in place. I used double sides tape to hold the circuit board to the back of the LCD module. I intend to put a piece of glass between the bezel and the LCD but unfortunately I have misplaced my glass cutter so until I find it that piece will be left out. I made a copper plate to line the hole for the controls. That is handy since it means the recharge socket and the RCA socket can share a ground (via the copper).

I made a small additional circuit board containing a Ni-Mh constant current charge circuit. When the batteries are flat you plug in a 12 volt supply and the batteries are charged over 15 hours (overnight). It’s not a very smart charger but as long as you disconnect the batteries before 18 hours they will be fine.

IMG_2651_1 Charging board.

With the batteries in place along side the keypad the final brass plate holds them nicely in place. The whole unit is self contained on the wooden front which is then simply inserted into the book.

IMG_2649_1 IMG_2650_1 Complete unit.

As mentioned I moved the piezo and it now sits so the sound comes out of holes in the side of the well for the controls just underneath the toggle switch. The switch itself I extended slightly with some brass tube with a ball bearing soldered to the end.

Finally I sprayed the wooden front black. While the paint dried I fixed another bug in the code around the drawing of the ships. With that done I transferred the chips from the Arduino boards to my own circuit board and tried it out. And it worked!

IMG_2655_1 Central controls.

The next update will have the final pictures, the code and a small film of the game working and finally this will be done!

Am already collecting bits for my next project!

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