Comparing two output

Projects Programming
16

in this code Tx changes :

volatile float Tx = 0 ;

volatile float f = 0 ;

volatile float t = 0 ;
 
volatile int m = 0 ;

void setup() {
 
  Serial.begin(19200);
   Serial3.begin(38400);

  capture_pin2.config(CAPTURE_TIME_WINDOW);
attachInterrupt(digitalPinToInterrupt(2), measure , LOW );

}

void measure (){
  uint32_t status,duty,period;
  status=capture_pin2.get_duty_and_period(duty,period);

 t = (static_cast<double>(duty)/static_cast<double>(capture_pin2.ticks_per_usec()) );
  if ( (t > 1400) && (t < 1600))
{  Tx = t ;}

 }
void loop() {
 

  delay(20) ;

Serial.println(Tx); 
}

but in this code Tx doesn't change

volatile float Tx = 0 ;

volatile float f = 0 ;

volatile float t = 0 ;
 
volatile int m = 0 ;

void setup() {
 
  Serial.begin(19200);
   Serial3.begin(38400);

  capture_pin2.config(CAPTURE_TIME_WINDOW);
attachInterrupt(digitalPinToInterrupt(2), measure , LOW );

}

void measure (){
  uint32_t status,duty,period;
  status=capture_pin2.get_duty_and_period(duty,period);

 t = (static_cast<double>(duty)/static_cast<double>(capture_pin2.ticks_per_usec()) );
  if ( (t > 1400) && (t < 1600))
{  Tx = t ;}

 }
void loop() {

if (Tx - f > 5)
{
  
 f = Tx;
 
  m++;

 
}
  delay(20) ;

Serial.println(m);