Problem with using two interrupts (MEGA 2560)

Using Arduino Programming Questions
#1

Hi. i have some problem when using two interrupts on mega 2560 board. i use two hall effect sensor, one for water flow and other for rpm on a turbine. there are no output display on the serial monitor. i never use interrupts before and this is the first time.

here the code that i try to write. can anyone show me the correct way to write the code??

volatile int hallone;
int Calc;
int hallsensor = 2; 

volatile byte halltwo;
unsigned int rpm_hall;
unsigned long timeold;

void waterflow ()     
{ 
  hallone++;  
} 

 void turbinerpm()
 {
   halltwo++;
 }
 
void setup() 
{ 
  pinMode(hallsensor, INPUT);
  Serial.begin (9600); 
  attachInterrupt(0, waterflow, RISING); 
  attachInterrupt(1, turbinerpm, RISING);
  halltwo = 0;
  rpm_hall = 0;
  timeold = 0;  
}

void loop() 
{  
   interrupts ();
   hallone = 0;  
   Calc = (hallone * 60 / 7.5);
   Serial.print (Calc, DEC); 
   Serial.println (" L/hour\r\n");
   delay (1000);
  noInterrupts ();
  
  interrupts ();
  if (halltwo >= 20) 
  { 
  rpm_hall = 30*1000/(millis() - timeold)*halltwo;
  halltwo = 0;
  Serial.println(rpm_hall,DEC);
  noInterrupts ();
}
}

thank you…

#2

Check your wiring. Which Arduino pins are the Hall sensors connected to and do you have resistors on them to pull their voltage high or low ?

Incidentally, the result of this calculation  Calc = (hallone * 60 / 7.5);will be an integer despite the division by 7.5 because Calc is defined as an int.

#3

the pins for both sensor are correct. i use 10K on both sensors to pull high.

#4

Do the interrupt pins get pulled low by the Hall sensors when they are activated ? In other words are the Hall sensors wired from the interrupt pins to ground ?

#5

Why are you disabling and then immediately re-enabling interrupts:

  noInterrupts ();
  
  interrupts ();

?

Why are you disabling interrupts at the end of loop(), and then immediately re-enabling them:

void loop() 
{  
   interrupts ();
<snip>
  noInterrupts ();
}

Add an LED with resistor, and toggle it in the ISR, to confirm that interrupts are happening (after you stop diddling with them).

#6

Sorry for the late reply. Thanks for both reply. well, i just been school on interrupt on the other forum. it is my mistake to put interrupt() and nointerrupt(). i just have to put interrupt() on setup and it work. thanks for the reply.

#7

i just have to put interrupt() on setup and it work.

Since the default state is interrupts enabled, you don't even need to do that.

#8 
   hallone = 0;  
   Calc = (hallone * 60 / 7.5);

I'm going to go out on a limb here and predict that Calc is pretty much always ending up 0. Is this what you intended?

#9