Snake Game

1// The MAX7219 uses SPI communication protocol...Hence, import SPI.h library
2#include <SPI.h>
3
4// The chip select pin
5#define CS 10
6
7// Few necessary registers for configuring the MAX7219 chip
8#define DECODE_MODE 9
9#define INTENSITY 0x0A
10#define SCAN_LIMIT 0x0B
11#define SHUTDOWN 0x0C
12#define DISPLAY_TEST 0x0F
13
14// Buttons used for controlling the snake
15#define left_button 2
16#define right_button 3
17
18volatile byte move_left = 0;
19volatile byte move_right = 0;
20
21// Varibles for snake
22int snake_l = 2;
23const int max_len = 15;
24int snake[max_len][2];
25byte cur_heading = 0;
26
27// Variable for food blob
28int blob[2] = { 0, 0 };
29int is_eaten = 1;
30
31// The game scene
32byte scene[8] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
33
34// A general function to send data to the MAX7219
35void SendData(uint8_t address, uint8_t value) {
36  digitalWrite(CS, LOW);
37  SPI.transfer(address);   // Send address.
38  SPI.transfer(value);     //   Send the value.
39  digitalWrite(CS, HIGH);  // Finish transfer.
40}
41
42// Function to initialize the game variables
43void init_game() {
44  is_eaten = 1;
45  move_left = 0;
46  move_right = 0;
47  cur_heading = 0;
48  snake_l = 2;
49  for (int i = 0; i < max_len; i++)
50    for (int j = 0; j < 2; j++)
51      snake[i][j] = 0;
52  snake[max_len - 1][0] = 2;
53  snake[max_len - 1][1] = 5;
54  snake[max_len - 2][0] = 1;
55  snake[max_len - 2][1] = 5;
56  refresh_scene();
57  while ((move_left || move_right) == 0)
58    ;
59  move_left = 0;
60  move_right = 0;
61}
62
63// Function to draw snake on gamescene
64void spawn_snake() {
65  // If the snake goes out of the scene, it enters from the other side
66  for (int j = max_len - snake_l; j < max_len; j++) {
67    if (snake[j][0] <= 0)
68      snake[j][0] = 8 + snake[j][0];
69    else if (snake[j][0] >= 9)
70      snake[j][0] = snake[j][0] - 8;
71    if (snake[j][1] <= 0)
72      snake[j][1] = 8 + snake[j][1];
73    else if (snake[j][1] >= 9)
74      snake[j][1] = snake[j][1] - 8;
75
76    // Draw the snake on the LED matrix
77    scene[snake[j][0] - 1] |= (1 << (snake[j][1] - 1));
78  }
79}
80
81// Function to update the position and length of the snake
82void snake_move() {
83  // If snake eats a blob...Increase length
84  if (snake[max_len - 1][0] == blob[0] && snake[max_len - 1][1] == blob[1]) {
85    is_eaten = 1;
86    snake_l += 1;
87  }
88
89  // Move each pixel forward
90  for (int i = snake_l - 1; i >= 1; i--) {
91    snake[max_len - 1 - i][0] = snake[max_len - i][0];
92    snake[max_len - 1 - i][1] = snake[max_len - i][1];
93  }
94
95  // Move the head according to button input
96  if (move_left == 1) {
97    if (cur_heading == 0) {
98      cur_heading = 1;
99      snake[max_len - 1][1] -= 1;
100    } else if (cur_heading == 1) {
101      cur_heading = 2;
102      snake[max_len - 1][0] -= 1;
103    } else if (cur_heading == 2) {
104      cur_heading = 3;
105      snake[max_len - 1][1] += 1;
106    } else if (cur_heading == 3) {
107      cur_heading = 0;
108      snake[max_len - 1][0] += 1;
109    }
110    move_left = 0;
111  } else if (move_right == 1) {
112    if (cur_heading == 0) {
113      cur_heading = 3;
114      snake[max_len - 1][1] += 1;
115    } else if (cur_heading == 1) {
116      cur_heading = 0;
117      snake[max_len - 1][0] += 1;
118    } else if (cur_heading == 2) {
119      cur_heading = 1;
120      snake[max_len - 1][1] -= 1;
121    } else if (cur_heading == 3) {
122      cur_heading = 2;
123      snake[max_len - 1][0] -= 1;
124    }
125    move_right = 0;
126  } else {
127    if (cur_heading == 0) {
128      snake[max_len - 1][0] += 1;
129    } else if (cur_heading == 1) {
130      snake[max_len - 1][1] -= 1;
131    } else if (cur_heading == 2) {
132      snake[max_len - 1][0] -= 1;
133    } else if (cur_heading == 3) {
134      snake[max_len - 1][1] += 1;
135    }
136  }
137}
138
139// Function to generate a blob and draw the blob on the gamescene
140void blob_generator() {
141  // If blob is eaten by the snake, generate one
142  if (is_eaten) {
143    blob[0] = random(1, 9);
144    blob[1] = random(1, 9);
145  }
146
147  // Draw the blob on the gamescene
148  scene[blob[0] - 1] |= (1 << (blob[1] - 1));
149  is_eaten = 0;
150}
151
152// Function to redraw the gamescene to the LED matrix with updated variables
153void refresh_scene() {
154  for (int i = 0; i < 8; i++)
155    scene[i] = 0x00;
156  snake_move();
157  spawn_snake();
158  blob_generator();
159  for (int i = 1; i < 9; i++)
160    SendData(i, scene[i - 1]);
161}
162
163// Callback for interrupt attached to left button
164void update_left() {
165  move_left = 1;
166}
167
168// Callback for interrupt attached to right button
169void update_right() {
170  move_right = 1;
171}
172
173// Setup function
174void setup() {
175  // GPIO Configuration
176  pinMode(left_button, INPUT_PULLUP);
177  pinMode(right_button, INPUT_PULLUP);
178  pinMode(CS, OUTPUT);
179  
180  // SPI configuration
181  SPI.setBitOrder(MSBFIRST);     // Most significant bit first
182  SPI.begin();                   // Start SPI
183  SendData(DISPLAY_TEST, 0x00);  // Finish test mode.
184  SendData(DECODE_MODE, 0x00);   // Disable BCD mode.
185  SendData(INTENSITY, 0x01);     // Use lowest intensity.
186  SendData(SCAN_LIMIT, 0x0f);    // Scan all digits.
187  SendData(SHUTDOWN, 0x01);      // Turn on chip.
188
189  // Random seed generation...Uses the noise in the analog channel 0 to create a random seed
190  randomSeed(analogRead(0));
191
192  // Attach interrupts to the buttons
193  attachInterrupt(digitalPinToInterrupt(left_button), update_left, FALLING);
194  attachInterrupt(digitalPinToInterrupt(right_button), update_right, FALLING);
195
196  // Enable interrupt
197  sei();
198
199  // Start the game
200  init_game();
201}
202
203void loop() {
204  // Check if snake is at max length
205  if (snake_l == max_len) {
206    // If yes, display win and restart
207    byte win_scene[8] = { B11100011, B00100100, B01000010, B11100100, B00000011, 0, B00011100, 0 };
208    for (int i = 1; i < 9; i++)
209      SendData(i, win_scene[i - 1]);
210    delay(5000);
211    init_game();
212  }
213
214  // Check if snake has collided with itself
215  for (int i = 0; i < max_len - 1; i++) {
216    if (snake[i][0] == snake[max_len - 1][0] && snake[i][1] == snake[max_len - 1][1]) {
217      // If yes, blink all leds and restart the game
218      delay(1000);
219      for (int j = 0; j < 4; j++) {
220        SendData(DISPLAY_TEST, 0x01);
221        delay(500);
222        SendData(DISPLAY_TEST, 0x00);
223        delay(500);
224      }
225      init_game();
226      break;
227    }
228  }
229  
230  // Keep refreshing the matrix with updated data....
231  refresh_scene();
232  // ...Every 0.5 secs
233  delay(500);
234}