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3.1.14 GAME– Not Not
=======================
Introduction
--------------------
In this lesson, we will make an interesting game device, and we call it \"Not Not\".
During the game, the dot matrix will refresh an arrow randomly. What you need to do is to press the button in the opposite direction of the arrow within a limited time. If the time is up, or if the button in the same direction as the arrow is pressed, you are out.
This game can really practice your reverse thinking, and now shall we have a try?
Components
---------------
.. image:: img/list_GAME_Not_Not.png
:align: center
Schematic Diagram
-----------------------
============ ======== ======== ===
T-Board Name physical wiringPi BCM
GPIO17 Pin 11 0 17
GPIO18 Pin 12 1 18
GPIO27 Pin 13 2 27
GPIO20 Pin 38 28 20
GPIO26 Pin 37 25 26
============ ======== ======== ===
.. image:: img/Schematic_three_one14.png
:align: center
Experimental Procedures
-----------------------------
**Step 1:** Build the circuit.
.. image:: img/image280.png
:width: 800
**Step 2:** Go to the folder of code.
.. raw:: html
.. code-block::
cd ~/davinci-kit-for-raspberry-pi/c/3.1.14/
**Step 3**: Compile.
.. raw:: html
.. code-block::
gcc 3.1.14_GAME_NotNot.c -lwiringPi
**Step 4**: Run.
.. raw:: html
.. code-block::
sudo ./a.out
After the program starts, a left or right arrow will be refreshed at
random on the dot matrix. What you need to do is to press the button in
the opposite direction of the arrow within a limited time. Then
\"**√**\" appears on the dot matrix. If the time is up, or if the
button in the same direction as the arrow is pressed, you are out and
the dot matrix displays \"x\". You can also add 2 new buttons or replace
them with Joystick keys for up, down, left and right— 4 directions to
increase the difficulty of the game.
.. note::
If it does not work after running, or there is an error prompt: \"wiringPi.h: No such file or directory\", please refer to :ref:`install_wiringpi_pi5`.
**Code Explanation**
Based on :ref:`1.1.6_matrix_c_pi5`, this lesson adds **2** buttons to
make an amusing game device.
The whole program process is as below:
1. Randomly select an arrow direction and generate **timer 1**.
2. Display the arrow image on the dot matrix.
3. Judge the button input. If the button is pressed or **timer 1**
reminds time’s up, judgement starts.
4. Display the image on the basis of a judging result; meanwhile,
generate **timer 2**.
5. Rerun **step 1** when **timer 2** reminds time’s up.
.. code-block:: c
struct GLYPH{
char *word;
unsigned char code[8];
};
struct GLYPH arrow[2]=
{
{"right",{0xFF,0xEF,0xDF,0x81,0xDF,0xEF,0xFF,0xFF}},
// {"down",{0xFF,0xEF,0xC7,0xAB,0xEF,0xEF,0xEF,0xFF}},
// {"up",{0xFF,0xEF,0xEF,0xEF,0xAB,0xC7,0xEF,0xFF}},
{"left",{0xFF,0xF7,0xFB,0x81,0xFB,0xF7,0xFF,0xFF}}
};
struct GLYPH check[2]=
{
{"wrong",{0xFF,0xBB,0xD7,0xEF,0xD7,0xBB,0xFF,0xFF}},
{"right",{0xFF,0xFF,0xF7,0xEB,0xDF,0xBF,0xFF,0xFF}}
};
GLYPH structure works like a dictionary: the **word** attribute
corresponds to the **key** on the dictionary; the **code** attribute
corresponds to the **value**.
Here, code is used to store an array for dot matrix to display images
(an 8x8 bit array).
Here, the array **arrow** can be used to display the arrow pattern in
up, down, left and right directions on the LED dot matrix.
Now **down** and **up** are commented and uncomment them if needed.
The array **check** is used to display these two images: \"**×**\" and
\"**√**\".
.. code-block:: c
char *lookup(char *key,struct GLYPH *glyph,int length){
for (int i=0;i>i);
hc595_out();
}
}
Display the specified pattern on the dot matrix.
.. code-block:: c
void createGlyph(){
srand(time(NULL));
int i=rand()%(sizeof(arrow)/sizeof(arrow[0]));
waypoint=arrow[i].word;
stage="PLAY";
alarm(2);
}
The function **createGlyph()** is used to randomly select a direction
(the word attribute of an element in the array **arrow[]:**
\"**left**\", \"**right**\"... ). Set the stage as \"PLAY\" and start
a 2-second alarm clock function.
**srand(time(NULL)):** Initializes random seeds that are from the system
clock.
**(sizeof(arrow)/sizeof(arrow[0]))：** Get the length of the array, the
outcome is 2.
**rand()%2:** The remainder is **0** or **1,** gotten from dividing a
generated random number by 2.
**waypoint=arrow[i].word:** The outcome should be \"right\" or \"left\".
.. code-block:: c
void checkPoint(char *inputKey){
alarm(0)==0;
if(inputKey==waypoint||inputKey=="empty")
{
waypoint="wrong";
}
else{
waypoint="right";
}
stage="CHECK";
alarm(1);
}
checkPoint() is used to check the button input; if the button is not
pressed or the button in the same direction as the arrow is pressed, the
outcome of the waypoint is wrong and \"**x**\" appears on the dot
matrix. Otherwise, the waypoint is right and dot matrix displays
\"**√**\". Here the **stage** is **CHECK,** and there can be set a
1-second alarm clock function.
alarm() is also called \"alarm clock\", in which a timer can be set, and
it sends **SIGALRM** signals to the progress when the defined time is
up.
.. code-block:: c
void getKey(){
if (digitalRead(AButtonPin)==1&&digitalRead(BButtonPin)==0)
{checkPoint("right");}
else if (digitalRead(AButtonPin)==0&&digitalRead(BButtonPin)==1)
{checkPoint("left");}
}
getKey() reads the states of the these two buttons; if the right button
is pressed, the parameter of the function checkPoint() is **right** and
if the left button is pressed, the parameter is **left**.
.. code-block:: c
void timer(){
if (stage=="PLAY"){
checkPoint("empty");
}
else if(stage=="CHECK"){
createGlyph();
}
}
Previously, timer() was called when set as the alarm() time’s up. Then
under the \"PLAY\" mode, checkPoint() is to be called to judge the
outcome. If the program is set to \"CHECK\" mode, the function
createGlyph() should be called to select new patterns.
.. code-block:: c
void main(){
setup();
signal(SIGALRM,timer);
createGlyph();
char *code = NULL;
while(1){
if (stage == "PLAY")
{
code=lookup(waypoint,arrow,sizeof(arrow)/sizeof(arrow[0]));
display(code);
getKey();
}
else if(stage == "CHECK")
{
code = lookup(waypoint,check,sizeof(check)/sizeof(check[0]));
display(code);
}
}
}
The working of the function signal(SIGALRM,timer): calling the timer()
function when a SIGALRM signal (generated by the alarm clock function
alarm()) is received.
When the program starts, call createGlyph() one time at first and then
start the loop.
In the loop: under PLAY mode, the dot matrix displays arrow patterns and
check the button state; if under CHECK mode, what is displayed is
\"**x**\" or \"**√**\".