The tower of Hanoi animated on an OLED display

1/****** The Tower of Hanoi ******/
2
3#include <U8g2lib.h>
4U8G2_SH1106_128X64_NONAME_F_HW_I2C
5  u8g2(U8G2_R0);
6
7int disksNumber=5;
8int speedDelay=400;
9int animDelay=7;
10
11int tower[3][10];
12
13const int downPin=A7;
14const int upPin=2;
15const int startPin=3;
16volatile bool downPressed=false;
17volatile bool upPressed=false;
18volatile bool startPressed=false;
19
20/* Display the 3 towers on the screen */
21
22void displayTowers(void)
23{
24  u8g2.clearBuffer();
25
26/* Draw the 3 rods */
27  for(int i=0; i<3; i++)
28    u8g2.drawBox(30+32*i, 23, 3, 40);
29
30/* Draw the disks */
31  for(int i=0; i<3; i++)
32    for(int j=0; j<10; j++)
33      if(tower[i][j]!=0)
34        u8g2.drawBox(28+32*i-tower[i][j],
35                     60-4*(j),
36                     8+2*tower[i][j], 3);
37
38  u8g2.sendBuffer();
39}
40
41/* Manage the speed of the game by controlling
42   the speed delay with up and down push
43   buttons then by applying this delay */
44
45void manageGameSpeed(void)
46{
47  if(upPressed)
48  {
49    if(speedDelay>=100) speedDelay-=100;
50    upPressed=false;
51  }
52  if(downPressed)
53  {
54    if(speedDelay<1000) speedDelay+=100;
55    downPressed=false;
56  }
57  delay(speedDelay);
58}
59
60/* Adjust the number of disks with the up
61   and down push buttons then start the game
62   with the start push button */
63
64void initGame(void)
65{
66  bool buttonPressed=true;
67
68  while(!startPressed)
69  {
70    if(upPressed)
71    {
72      if(disksNumber<9) disksNumber++;
73      buttonPressed=true;
74      upPressed=false;
75    }
76    if(downPressed)
77    {
78      if(disksNumber>1) disksNumber--;
79      buttonPressed=true;
80      downPressed=false;
81    }
82    if(buttonPressed)
83    {
84/* Empty the 3 towers */
85      for(int i=0; i<3; i++)
86        for(int j=0; j<10; j++)
87          tower[i][j]=0;
88/* Then put the right number of disks onto
89   the first tower */
90      for(int i=0; i<disksNumber; i++)
91        tower[0][i]=disksNumber-i;
92
93      displayTowers();
94      buttonPressed=false;
95    }
96  }
97  startPressed=false;
98}
99
100/* Calculate the height of a tower */
101
102int height(int towerNumber)
103{
104  int h;
105
106  for(h=0; tower[towerNumber][h]!=0; h++);
107  return h;
108}
109
110/* Move one disk from a tower to another. An
111   animation is obtained by some intermediate
112   positions */
113
114void moveOnediskAnimated(int from, int to)
115{
116  int hFrom;
117  int hTo;
118  int diskToMove;
119
120/* Calculate the heights of the two stacks */
121  hFrom=height(from);
122  hTo=height(to);
123  diskToMove=tower[from][hFrom-1];
124  
125/* Lift the disk just above its original  
126   position then wait for animDelay */
127  tower[from][hFrom-1]=0;
128  tower[from][hFrom]=diskToMove;
129  displayTowers();
130  delay(animDelay);
131
132/* Erase the disk then wait for animDelay.
133   Your brain will imagine that the disk is
134   between the two towers */
135  tower[from][hFrom]=0;
136  displayTowers();
137  delay(animDelay);
138
139/* Draw the disk just above its final position
140   then wait for animDelay */
141  tower[to][hTo+1]=diskToMove;
142  displayTowers();
143  delay(animDelay);
144
145/* Draw the disk at its final position */
146  tower[to][hTo+1]=0;
147  tower[to][hTo]=diskToMove;
148
149  displayTowers();
150  manageGameSpeed();
151
152/* Manage the pause with the start push
153   button */
154  if(startPressed)
155  {
156    startPressed=false;
157    while(!startPressed);
158    startPressed=false;
159  }
160}
161
162/* Recursive function that moves a stack
163   of n disks from a rod to another in the
164   minimal number of moves. If the stack
165   to be moved is not empty move the n-1 disks
166   which are above the stack towards the third
167   rod by calling the move function, then move
168   the disk which was at the bottom of the
169   stack towards its final position, then move
170   the disks which has been put on the third
171   rod towards the final rod by calling the
172   move function again. */
173
174void move(int from, int to, int n)
175{
176  if(n!=0)
177  {
178/* Calculate the intermediate rod number */
179    int intermediate=3-to-from;
180
181    move(from, intermediate, n-1);
182    moveOnediskAnimated(from, to);
183    move(intermediate, to, n-1);
184  }
185}
186
187/* The 3 interrupt routines that are called
188   when you press a push button */
189void interruptRoutineReadDown(void)
190{
191  noInterrupts();
192  delayMicroseconds(10000);
193  if(digitalRead(downPin)==LOW)
194    downPressed=true;
195  interrupts();
196}
197
198void interruptRoutineReadUp(void)
199{
200  noInterrupts();
201  delayMicroseconds(10000);
202  if(digitalRead(upPin)==LOW)
203    upPressed=true;
204  interrupts();
205}
206
207void interruptRoutineReadStart(void)
208{
209  noInterrupts();
210  delayMicroseconds(10000);
211  if(digitalRead(startPin)==LOW)
212    startPressed=true;
213  interrupts();
214}
215
216void setup()
217{
218  u8g2.begin();
219  pinMode(downPin, INPUT_PULLUP);
220  pinMode(upPin, INPUT_PULLUP);
221  pinMode(startPin, INPUT_PULLUP);
222  attachInterrupt(digitalPinToInterrupt
223                   (downPin),
224         interruptRoutineReadDown,FALLING);
225  attachInterrupt(digitalPinToInterrupt
226                   (upPin),
227         interruptRoutineReadUp, FALLING);
228  attachInterrupt(digitalPinToInterrupt
229                   (startPin),
230         interruptRoutineReadStart, FALLING);
231}
232
233void loop()
234{
235  initGame();
236  move(0, 2, disksNumber);
237  while(!startPressed);
238  startPressed=false;
239}