Line-by-line explanation of the code that was programmed into the Arduino:

Format of this file: (“Line Number: Commentary”);

1: import premade EYW library to reduce work;
2: Construct a new “Altimeter” object named ‘a’;
3: begin setup() method, setup() runs once and returns nothing;
4: Initialize the refresh rate of the Serial connection to the computer;
5: output the string “Initializing…..\n” to the Serial monitor;
6: output the result of String begin() to the Serial monitor, begin() initializes the altimeter and sets up default ports for I/O;
7: run the calibrate(int i) method, more specifically it takes 10 measurements of barometric air pressure and sets the pressure sensor to 0;
8: runs the pinMode(int pin, mode) method, which initializes pin as a mode, either INPUT or OUTPUT, in this case, it initializes pin 5 as an OUTPUT;
9: declares two boolean values, lifted and dropped, which are used to determine when to begin taking altitude measurements and to determine if the capsule has landed;
10: declares an array of integers, heights[], which has a length of 20, to store height values to allow for data collection;
11: begin loop() method, this method is an infinite loop and will run until the Arduino turns off, it also returns nothing;
12: begin for loop, this iterates through the code inside the loop 10 times, once a second;
13: ouptut the string “Measuring Altitude: “ to the serial monitor for human observation;
14: takes 10 measurements of air pressure, converts each to an altitude, and then averages them, putting them into heights at index i, which increments with the for loop;
15: output the value stored in the i-th index of heights to the serial monitor;
16: checks if the value stored in the i-th index of heights is greater than the value stored in the i-1 th index of heights;
17: if the condition in line 16 is true, then set lifted to true;
18: checks if the value stored in the i-1 th index of heights is greater than the value stored in the ith index of heights;
19: if the condition in line 18 is true, then set dropped to true;
20: declare an integer speed which gets twice the sum of the i-3th index and the i-2th index of heights;
21: begin while loop, this only begins if the ith and i-1 th indices of heights are equal and both lifted and dropped are true;
22: begin switch statement to determine what sound is ouputted, the deciding value is speed%10, or the remainder when speed is divided by 10 (for two digit numbers);
23: this case will run if speed%10 is 1;
24: sound the alarm once for 250ms, a dot or dit;
25: wait 10 ms;
26: sound the alarm four times for 500 ms, four dashes or dahs;
27: break out of the switch statement and to the end of the while loop;
28-69: repeat for every digit from 2-9 and 0;
70: this case is the default case and will only run if there is an error in the code/altimeter failure;
71: wait 1500 msec between numbers;
72: check to see if current height is greater than the last height before beginning beeping;
73: set boolean lifted to false;
74: reset heights[] to zero;
75: set i to zero and reset the for loop;
77: wait 500 msec between loops of the for loop;