This sketch is used by Exercise: Event-Loop Programming.
Full Source Code
The full code is all in one file EventLoopDemo.ino.
// EventLoopDemo.ino : demonstrate generation of two simultaneous square waves at different rates // The example program generates audio-frequency square waves at different // pitches on pins 4 and 5 to demonstrate a simple event-loop control structure // allowing parallel execution of two timed tasks. The exercise asks the // student to add an analog potentiometer input and use the input value to // modulate the pitch by varying the waveform timing. // Define the pin numbers on which the outputs are generated. const int outputPin1 = 4; const int outputPin2 = 5; /****************************************************************/ // This function is called once after reset to initialize the program. void setup() { // Initialize the digital output pins to output drive mode. pinMode( outputPin1, OUTPUT ); pinMode( outputPin2, OUTPUT ); } /****************************************************************/ // Global variables. long next_output_time_1 = 0; // timestamp in microseconds for when next to update output 1 long next_output_time_2 = 0; // timestamp in microseconds for when next to update output 2 long output_interval_1 = 500; // interval in microseconds between output 1 updates long output_interval_2 = 700; // interval in microseconds between output 2 updates int output_state_1 = LOW; // current state of output 1 int output_state_2 = LOW; // current state of output 2 /****************************************************************/ // This function is called repeatedly as fast as possible from within the // built-in library to poll program events.
Read more: Arduino Sketch Event Loop Demo