Frequency counter problem at low frequency

Projects Programming
1

I have a frequency counter code using pulseIn command. It's measuring a sweeping frequency, so 20 pulses at 1hz 20 at 2 hz to 20 at 6 hz. These all have a 10% duty cycle
I'm using Ltime to measure the low time and Htime to measure the high time.
The problem I have is for the 1hz and 2 hz the Ltime is measuring 0.0 , the high time measures correctly . The low time for the other frequencies measures fine.
the consiquence of this is the 1hz is displayed as 10hz and the 2hz displayed as 20 hz.

#include <LiquidCrystal.h>
LiquidCrystal lcd(7,6,5,4,3,2);
unsigned long Htime;
float Ltime;
float Ttime;
float frequency;
float hightime;


void setup() {
  // put your setup code here, to run once:
pinMode(8,INPUT);
lcd.begin(16,2);

}

void loop() {
  // put your main code here, to run repeatedly:
lcd.clear();  
lcd.setCursor(0,0);
lcd.print("Frquency ");
Htime=pulseIn(8,HIGH);
Ltime=pulseIn(8,LOW),
Ttime=Htime+Ltime;
frequency=(1000000)/Ttime;

lcd.setCursor(2,2);
lcd.print(frequency);
lcd.print("  Hz");
delay(2000);
}
2 
Htime=pulseIn(8,HIGH);
Ltime=pulseIn(8,LOW),

What type does pulseIn() return? Why are you storing the value in a different type?

What is the DOCUMENTED resolution of pulseIn() in the units it returns?

The problem I have is for the 1hz and 2 hz the Ltime is measuring 0.0 , the high time measures correctly .

Where is your proof?

3

It is not easy to measure low and high frequencies with the same code.
There are two good libraries, here is the difference: www.pjrc.com/teensy/td_libs_FreqMeasure.html#compare

4

Hi,
I replaced the "frequency" with Htime and then Ltime so that I could read ms it was measuring and for 1hz and 2 hz the Ltime came back as 0.0

5

Problem solved.
I added a long timeout on the Ltime function

Ltime=pulseIn(8,LOW,100000000)
it works perfectly now