1. //L293D
2. //Motor A
3. const int motorPin1  = 9;  // Pin 14 of L293
4. const int motorPin2  = 10;  // Pin 10 of L293
5. //Motor B
6. const int motorPin3  = 12; // Pin  7 of L293
7. const int motorPin4  = 11;  // Pin  2 of L293
8.  
9. #define TIME_WAIT 15000
10.  
11. void setup() {
12.   //Set pins as outputs
13.   pinMode(motorPin1, OUTPUT);
14.   pinMode(motorPin2, OUTPUT);
15.   pinMode(motorPin3, OUTPUT);
16.   pinMode(motorPin4, OUTPUT);
17. }
18.  
19. void left_stop() {
20.   digitalWrite(motorPin1, LOW);
21.   digitalWrite(motorPin2, LOW);
22. }
23.  
24. void right_stop() {
25.   digitalWrite(motorPin3, LOW);
26.   digitalWrite(motorPin4, LOW);
27. }
28.  
29. void stop() {
30.   left_stop();
31.   right_stop();
32. }
33.  
34. void left_forward() {
35.   digitalWrite(motorPin1, LOW);
36.   digitalWrite(motorPin2, HIGH);
37. }
38.  
39. void left_backward() {
40.   digitalWrite(motorPin1, HIGH);
41.   digitalWrite(motorPin2, LOW);
42. }
43.  
44. void right_forward() {
45.   digitalWrite(motorPin3, LOW);
46.   digitalWrite(motorPin4, HIGH);
47. }
48.  
49. void right_backward() {
50.   digitalWrite(motorPin3, HIGH);
51.   digitalWrite(motorPin4, LOW);
52. }
53.  
54. void forward() {
55.   left_forward();
56.   right_forward();
57. }
58.  
59. void backward() {
60.   left_backward();
61.   right_backward();
62. }
63.  
64. void left_rotate() {
65.   left_backward();
66.   right_forward();
67. }
68.  
69. void right_rotate() {
70.   left_forward();
71.   right_backward();
72. }
73.  
74. void left_circle() {
75.   left_stop();
76.   right_forward();
77. }
78.  
79. void right_circle() {
80.   right_stop();
81.   left_forward();
82. }
83.  
84. void wait() {
85.   delay(TIME_WAIT);
86.   stop();
87. }
88.  
89. void loop() {
90.   forward();
91.   wait();
92.   backward();
93.   wait();
94.   left_rotate();
95.   wait();
96.   right_rotate();
97.   wait();
98.   left_circle();
99.   wait();
100.   right_circle();
101.   wait();
102.   stop();
103.   delay(2000);
104. }