Build Your Own Retro Arcade Game
Build your own game console with a two-player table tennis game! Take
yourself back over 30 years and immerse yourself in the past, a time when the
first electronic game came to the market. The 'table' is depicted on a display
consisting of 120 individual LEDs and shows the bats and the ball. It is all
controlled by the modern ATmega8 microcontroller. Two knobs allow you and
your playing partner to move the bats. If you like, you can also play against
the microcontroller. Each new game is started by inserting a coin. The current
score is shown on the display and you can also choose the speed of the game.
Tips and tricks for the game as well as further information can be found online
at www.eight-innovation.com
Technical Information:
Operating voltage 4.5 V (three AA batteries required)
Operating time with a set of batteries: approx. 10 hours
ATmega8 microcontroller, 8kB flash, clock rate 8MHz
120 red SMD LEDs, multiplexed
Assembly
Components:
A)
B)
C)
D)
E)
F)
G)
H)
I)
Microcontroller circuit board with LED display
Two 10 kΩ linear potentiometers (‘pots’ for short)
Two knobs for pots
Battery compartment for three AA batteries
Insulated stranded hook-up wire
Two pre-cut bare wires (packed under ‘E’)
Plastic mounting housing
Plastic diffuser (not shown – packed under tray)
Four double-sided adhesive dots (not shown)
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The packaging also serves as the housing. All components are in the plastic
tray pack that is covered with a second transparent tray cover. The top tray is
required for assembly.
Click the circuit board into the tray and mount both pots into the housing with
the washers and nuts. The connections on the circuit board must point
towards the coin slot. Check from the front whether the LED field is centred
behind the screen opening. Adjust the position if required and then tighten
the first pot.
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The assembly should now look like this.
Next, prepare four pieces of wire. Cut two simple wires, one of 3cm and one
12cm.
Then cut two wires of about 15cm in length.
About 5mm on both ends of each wire should be stripped and tinned. If you
don't have much experience with soldering, tinning the ends of the wires is a
good practice as not much can go wrong.
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A short soldering course can be found at www.eight-innovation.com.
The longer 15cm wires should have an additional section stripped away,
approx. 3cm from the tinned end on the left side. Cut the insulation with a
sharp knife, be very careful and pull them apart from each other.
Tin the free ends. If this is difficult you could also use the separate wires that
are then connected on the circuit board.
Use the four prepared wires to wire the pots. The outside connections of both
pots are at connections P1 and P4. The central connection (pin) connects to
P2 (left) and P3 (right).
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Solder both of the pre-cut bare wires to the connections K1 and K2. The wires
must be guided through the mounting tray. The easiest way to do this is once
you have tinned the ends is to hot pierce them through the plastic tray.
Once the bare wires are soldered, you should bend them to form the coin
contact. Bend the wires so that they keep their distance but at the same time
so they can be connected together by a falling coin. Do a few tests and adjust
the contacts so that a coin can fall through fairly easily.
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Join the connecting wires of the battery compartment to the circuit board.
Pay attention to the polarity: The black wire (negative), goes to the GND
terminal on the left edge, the red wire (positive) goes on the 4.5 V connection
on the circuit board. On the circuit board you will find a polarity protection
diode. If you mix these wires up, nothing will break but the display will remain
blank.
The game is now more or less assembled. Now comes the big moment of
doing the first test. Insert the three batteries. Use 1.5 V AA alkaline
batteries.
If everything is connected correctly, the two bats will appear on the
display and they can be moved with the pots.
Now put the knobs on and adjust them so that they point at the bats.
Tighten up the grub screws.
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Once everything is working properly you can then mount the diffuser on
the display. There are double-sided sticky dots which can be used to stick
the lens onto the housing.
To close the magnetic cover, the mounting tray must be pushed in slightly
at the edge. However this can cause a problem should you want to take
the coin out the housing later. Therefore, very carefully cut off any excess
edging with a sharp knife or a pair of scissors.
Now you are ready to play!
Keep a few coins ready that you can use to start a new game. Should a
problem arise, take out the batteries and put them back in again after one
minute. This fully resets the microcontroller.
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Description of Functions and Playing Instructions
The players move their ping pong bats with the knobs. A ball is played back
and forth. If you manage to hit the ball past your opponent's bat, you win a
point. The winner is the first player to reach ten points. The first game starts
when the batteries have been inserted. At the end of the game, the display
turns off. You then need to insert a coin for every new game.
You can choose to play against the computer or a real opponent.
A computer vs. computer setting is also possible. The choice of player can be
selected at the beginning. Move one of the bats right to the top, this lets the
computer take control of the bat and this is indicated by flashing. You can give
the computer the left or the right side, or both if you wish. More options are
detailed below
Computer vs. Computer
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Left Player vs. Computer
For the first game to start, both bats must be in the middle position and then
you must wait for the game to start and the ball to appear on the server's
side. The serve is awarded to the player who has the lowest score.
Player vs.Player, server on the right
Serve the ball by touching it with the bat. Touching it on the straight side
makes it go horizontal. If the ball goes to the side of the bat, you need to
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move the bat and touch the ball with the edge of the bat so that it moves
either upwards or downwards at a 45-degree angle. It bounces off the side of
the court and will go to the opposite side of the angle.
The right bat hits the ball at an angle
The right bat hits the ball straight
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The opponent can hit a ball approaching at a horizontal angle with a flat bat
and return it at a 180 degree angle. A ball approaching at an angle can be
returned at a 90 degree angle.
If a ball approaches at an angle and hits an edge, it will be randomly returned
at either a 180-degree angle or horizontally. A horizontally approaching ball
can be returned at an angle with the edge.
Return with the edge
Return with the flat side
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Every time one of the two players misses the ball, the opponent wins a
point. The score is then displayed for a second as bars on the edge of the
playing area. Whoever has lost a point is the next to serve.
Score: 4:6
The game ends as soon as one of the players reaches a score of ten. The final
score will be displayed for three seconds. The game with then automatically
turn itself off. In order to start a new game, you must insert a coin. Now you
can chose the type of game again, who is the first to serve or if you want to play
against the computer.
The player options are displayed on the screen for about four seconds. In this
time you can also choose the difficulty level (Level 1 to level 5). A higher level
results in a faster game. Game level 1 is the slowest game speed. In order to
choose a faster speed, move your bats multiple times upwards and
downwards over the middle position. During this time, the level will be
displayed in the middle of the screen as a thick bar. Each level is represented
as a block of four dots.
When the bar reaches the top of the display you have selected the fastest
level.
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Speed level 3
At the start of the game you can also choose which of the two players will
serve. If both bats are placed at the top, the computer will play both sides
and the speed of the game will be chosen at random.
Technical Specifications
The game is built with an ATmega8-Controller. A matrix of 120 LEDs is
laid out in rows of ten, each with 12 LEDs. The microcontroller
controls the rows in a multiplex. The anodes are triggered directly by
ports, the cathodes by two HC4094 shift registers.
The pots are connected to ADC6 and ADC7. The upper end of the pot is
coupled to the VCC, the lower end to the PD2 port (INT0). At the end of the
game the PD2 programme switches up, so that there is no voltage is applied
to the pots. All LEDs are shut off, the AD converter stopped, and the
microcontroller is placed in power-down mode. Power consumption therefore
reduces to less than 1 µA. Therefore a master switch is not required. On PD2
and on GND there is also the coin contact (K1 and K2). These can interrupt
and start a new game.
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Further Projects!
You will find lots of unused connections on the circuit board. These are
partly required for manufacturing and are also useful for your own
projects. On the six pole ISP connection (bottom left) you can reprogramme the controller and create your own project. Only do this when
you are familiar with microcontrollers, because if you make a mistake the
system can be irreparably damaged. In addition there are also eight free
port connections that can be used for other things. The C4 connection has
active firmware and serves as a test input. If you put C4 in GND and connect
the operating voltage or trigger a reset, the display will perform a test in
which all LEDs are triggered.
More on additional uses and further technical information can be found
online at www.eight-innovation.com. When you have had enough of playing
the game and you want to know what else it can do, then that’s the place to
go!
Disclaimer
© 2015 Eight Innovation Ltd & Franzis Verlag GmbH
www.eight-innovation.com
All rights reserved, including photocopying and storing in electronic media.
Creating and distributing copies on paper on data carriers or on the
internet, in particular as a PDF is only permitted with explicit permission of
the publisher and failing to do so will lead to criminal prosecution.
Most of the product descriptions of hard- and software as well as company
names and company logos named in this document are, as a rule, registered
trademarks and should be treated as such. The publisher will largely use the
manufacturer's spellings in the product descriptions.
Everything presented in this book in regards to circuits and channels has been
developed, approved and tested with the utmost care. However any errors in
this book and in the software cannot be completely ruled out. The publisher
and author take no responsibility for any errors or incorrect information.
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