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//
// main.ino
//
// Testing reading from the receiver. We're expecting a PWM signal, on
// interrupt 0 (which is pin 2 on an Arduino Uno).
//
// This program tries to measure the frequency of the signal pulses in
// microseconds. It takes several measurements and prints out the average over
// serial.
//
// number of signal pulses to average
#define SIGNAL_SAMPLES 10
// set to the time that the last signal pulse was at
static volatile unsigned long _new_pulse_at = 0;
// ISR to handle the PWM signal
void signal_handler()
{
// record time
_new_pulse_at = micros();
}
void setup()
{
Serial.begin( 9600 );
// set up an interrupt handler on pin 2
attachInterrupt( 0, signal_handler, RISING );
}
void loop()
{
unsigned long last_pulse = 0;
unsigned long intervals[ SIGNAL_SAMPLES ] = {0};
int interval_idx = 0;
while( true )
{
// detect pulse
unsigned long new_pulse = _new_pulse_at;
bool got_pulse = false;
if( new_pulse < last_pulse )
last_pulse = new_pulse;
if( new_pulse > last_pulse )
{
// check interval
unsigned long interval = new_pulse - last_pulse;
if( interval < 300 )
{
Serial.print( "[" );
Serial.print( last_pulse );
Serial.print( "," );
Serial.print( new_pulse );
Serial.print( "]" );
}
// if( interval > 19000 && interval < 20500 )
// {
// update interval buffer
intervals[ interval_idx ] = interval;
if( ++interval_idx >= SIGNAL_SAMPLES )
interval_idx = 0;
got_pulse = true;
// }
last_pulse = new_pulse;
}
// display average?
if( interval_idx == 0 && got_pulse )
{
// calculate average
for( int a = 0; a < SIGNAL_SAMPLES; a++ ) {
Serial.print( intervals[ a ] );
if( a == SIGNAL_SAMPLES - 1 )
Serial.println();
else
Serial.print( " " );
}
}
}
}
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