Snake Game
Corbett Crook and Chris Rice
Our Project
● We chose to recreate
the classic snake game
● However, due to
limitations of the HCS12
we had to modify our
original design to create
an original game
inspired by snake.
How we changed it
● For our variation, the snake does not grow.
Instead it becomes faster every time you
eat.
● The goal is to eat as much food as you can
without running into a wall.
Hardware
● Graphic LCD from
SparkFun
● HCS12 Microcontroller
● Pushbuttons
● Logic Level Converter
(MAX232)
Schematic
Software Goals
● Communicate with the LCD via the SCI.
● Check for button presses periodically
using the RTI system.
● Create game logic for the snake
Snake Logic
●
To draw snake segments we need to store an x and y
position of the pixel and the direction that pixel
should move on the next frame
●
When a new frame is drawn the direction value on
the 0th pixel of the snake (the head) Is copied to the
second pixel, and the old value of the second pixel is
copied to the third pixel, and so on propagating down
the length of the snake vector
●
The direction value of the snakehead is determined
by a direction flags, which are set when a player
pushes a button
Get Input From User
●
We used the RTI system to get input from the user on
how the snake should move
●
At regular time intervals the system checks for a
button press from the user and sets the appropriate
flag
●
The system interrupt timing is set so that it should
always be able to catch a button press during the
time during which the user holds the button down
Draw Snake Segments
●
We used the putCharSCI function from previous labs
to put ASCII characters into the SCIDRL register
●
Then functions were created to clear the screen and
draw snake and food pixels, using special commands
included with the sparkfun LCD chip
●
Loops in our main function called these functions
each time it needed to draw or erase a pixel on the
screen
Conclusion
Just like many great video game classics hardware limitations actually
contributed to the game design by creating challenges for us to work
around
We feel like this game captures the spirit and fun of the original
snake without being the same game. It is enjoyable and entertaining
for everyone
Not only that but we also learned a few new tricks with the HCS12 in
addition to using our old ones in order to complete this project