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3.1.13 GAME– NotNot

Introduction

In this project, 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?

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Raphael Kit	337	Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
GPIO Extension Board	BUY
Breadboard	BUY
Jumper Wires	BUY
LED Matrix Module	BUY
Button	BUY

Schematic Diagram

T-Board Name	physical	wiringPi	BCM
GPIO22	Pin 15	3	22
GPIO23	Pin 16	4	23
SPIMOSI	Pin 19	12	MOSI
SPICE0	pin 24	10	CE0
SPISCLK	Pin 23	14	SCLK

Experimental Procedures

Step 1: Build the circuit.

Step 2: Turn on the SPI before starting the experiment, refer to SPI Configuration for details.

Step 3: Go to the folder of the code.

cd ~/raphael-kit/c/3.1.13/

Step 4: Compile the code.

make

Step 5: Run the executable file.

sudo ./3.1.13_GAME_NotNot

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, then “√” appears on the dot matrix. 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 Install and Check the WiringPi.

Code Explanation

This C program is designed to run on a Raspberry Pi using the WiringPi library. It interfaces with an 8x8 LED matrix display controlled by the MAX7219 driver chip and uses two buttons for user interaction. The program randomly displays a left or right arrow on the LED matrix, and the user must press the corresponding button. It then displays a check mark for a correct response or a cross for an incorrect one.

Header Files:
- wiringPi.h: Provides functions for GPIO control using the WiringPi library.
- wiringPiSPI.h: Provides functions for SPI communication.
- stdio.h: Standard input/output functions (printf, etc.).
- stdlib.h: Standard library functions (rand, srand, exit).
- time.h: Functions for manipulating date and time (time, NULL).
Type Definitions:
- #define uchar unsigned char: Defines uchar as an alias for unsigned char.
- #define uint unsigned int: Defines uint as an alias for unsigned int.
Constants and Macros:
- SPI_CHANNEL: SPI channel used for communication (0 or 1).
- SPI_SPEED: SPI communication speed set to 1 MHz.
- AButtonPin: WiringPi pin number for Button A (GPIO 22).
- BButtonPin: WiringPi pin number for Button B (GPIO 23).
Global Variables:
- int stage = 0;: Tracks the current stage of the game (displaying arrow or result).
Data Arrays:
- uchar arrow[2][8]: Contains two 8-byte patterns representing right and left arrows for the LED matrix.
  - arrow[0]: Right arrow pattern.
  - arrow[1]: Left arrow pattern.
- uchar check[2][8]: Contains two 8-byte patterns representing correct (check mark) and incorrect (cross) symbols.
  - check[0]: Correct symbol pattern.
  - check[1]: Incorrect symbol pattern.
void Delay_xms(uint x) Function:
- Wrapper function for delay(x) provided by WiringPi.
- Delays program execution for x milliseconds.
void Write_Max7219_byte(uchar DATA) Function:
- Sends a single byte (DATA) to the MAX7219 via SPI.
- Uses wiringPiSPIDataRW to perform SPI data transfer.
- DATA: The data byte to send.
void Write_Max7219(uchar address1, uchar dat1) Function:
- Sends a command and data to the MAX7219.
- Combines address1 (register address) and dat1 (data) into a buffer and sends via SPI.
- address1: Address of the MAX7219 register.
- dat1: Data to write to the register.
void Init_MAX7219() Function:
- Initializes the MAX7219 display driver with necessary configurations.
- Configures decode mode, intensity, scan limit, shutdown mode, and display test.
- Clears any previous data on the display.
void Init_WiringPi() Function:
- Initializes the WiringPi library and SPI interface.
- Sets up the button pins as input with pull-up resistors.
- Checks for successful initialization and exits if failed.
int get_index() Function:
- Generates a random index (0 or 1) to choose between left and right arrow.
- Returns: 0 or 1.
int get_key(uint num) Function:
- Waits for the user to press a button and determines if the input matches the displayed arrow.
- Parameters:
  - num: The index of the displayed arrow (0 for right, 1 for left).
- Returns:
  - 1 if the user input is correct.
  - 0 if the user input is incorrect.
- Functionality:
  - Enters an infinite loop checking the state of the buttons.
  - Uses digitalRead to detect button presses (active LOW).
  - Compares the pressed button with the expected input based on num.
void display(uint index) Function:
- Displays either an arrow or a result symbol on the LED matrix based on the stage.
- Parameters:
  - index: Index to select the pattern from arrow or check arrays.
- Functionality:
  - If stage == 0, displays an arrow pattern.
  - If stage == 1, displays a check mark or cross symbol.
Main Function:
- Initialization:
  - Seeds the random number generator with srand((unsigned)time(NULL)).
  - Calls Init_WiringPi() to set up GPIO and SPI.
  - Calls Init_MAX7219() to initialize the LED matrix display.
  - Introduces a short delay with Delay_xms(50).
- Game Loop (``while (1)``):
  - Stage 0 (Display Arrow):
    - Calls get_index() to randomly select an arrow direction.
    - Calls display(direction) to show the arrow on the LED matrix.
    - Sets stage = 1 to move to the next stage.
  - Stage 1 (Get User Input and Display Result):
    - Calls get_key(direction) to wait for user input and determine correctness.
    - Calls display(key) to show the result symbol (check mark or cross).
    - Waits for 1 second using Delay_xms(1000) to allow the user to see the result.
    - Sets stage = 0 to restart the loop.

Program Flow Summary:

Setup:
- Initialize WiringPi and SPI.
- Configure button pins and MAX7219 settings.
- Seed the random number generator.
Display Arrow:
- Randomly select an arrow direction (left or right).
- Display the corresponding arrow on the LED matrix.
User Interaction:
- Wait for the user to press either Button A or Button B.
- Determine if the pressed button matches the arrow direction.
Display Result:
- Show a check mark if the user’s input is correct.
- Show a cross if the user’s input is incorrect.
- Wait for 1 second before the next round.
Repeat:
- Loop back to display a new arrow and continue the game.