Hello,
I'm working with the Arduino Due ans I used the following code:
// period of pulse accumulation and serial output, milliseconds
#define MainPeriod 100
long previousMillis = 0; // will store last time of the cycle end
volatile unsigned long duration=0; // accumulates pulse width
volatile unsigned int pulsecount=0;
volatile unsigned long previousMicros=0;
void setup()
{
Serial.begin(19200);
attachInterrupt(6, myinthandler, RISING);
}
void loop()
{
unsigned long currentMillis = millis();
if (currentMillis - previousMillis >= MainPeriod)
{
previousMillis = currentMillis;
// need to bufferize to avoid glitches
unsigned long _duration = duration;
unsigned long _pulsecount = pulsecount;
duration = 0; // clear counters
pulsecount = 0;
float Freq = 1e6 / float(_duration);
Freq *= _pulsecount; // calculate F
// output time and frequency data to RS232
Serial.print(currentMillis);
Serial.print(" "); // separator!
Serial.print(Freq);
Serial.print(" ");
Serial.print(_pulsecount);
Serial.print(" ");
Serial.println(_duration);
}
}
void myinthandler() // interrupt handler
{
unsigned long currentMicros = micros();
duration += currentMicros - previousMicros;
previousMicros = currentMicros;
pulsecount++;
}
to measure the frequency.
I can measure frequencies higher than 1.5kHz accurately, but I can't seem to measure lower frequencies.
How can I measure lower frequencies, say 400Hz and above?
Thanks.
