Collecting bulk data with the Arduino

First, we'll expand our IR sensor reading sketch to wait for the sensor to show a stable reading. We'll use this stable reading algorithm to gather a batch of 16 samples from the sensor. This will give us some data that we can use for calibration.

The expanded version of the gather_data() function includes three separate features. We've left them in a single function, but they can be decomposed if required to make the Arduino more responsive. Here are the global variables shared by gather_data() and share_data():

unsigned long start_time, end_time;
int raw_reading;
#define MODE_LIMIT 6
int reading[MODE_LIMIT];
int count[MODE_LIMIT];

const int TIME_LIMIT = 5000; // Microseconds.

We defined three important features for our data collection: the start time for reading, the end time for reading, and the raw value that was read. We included two other pieces of data definition that are unique to the Arduino language.

The #define statement creates a symbol that...