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Topic: what input pin is it using? (Read 6017 times) previous topic - next topic

Joes

hi there just looking into using a hall sensor on my arduino and came across this code below, i dont know if im being blind but where does it state which input pin its using?

Code: [Select]



const int ledPin = 13;
volatile int rpmcount;
int sensorState = 0;
unsigned int rpm;
unsigned long timeold;

void rpm_fun()
{
      rpmcount++;
      digitalWrite(ledPin, HIGH);
      delay(50);
      digitalWrite(ledPin, LOW);
}

void setup() {
  pinMode(ledPin, OUTPUT);     
  Serial.begin(9600); 
  attachInterrupt(0, rpm_fun, FALLING); 
}

void loop(){
 
   if(rpmcount>=5) {
      rpm=(60000*rpmcount)/(8*(millis()-timeold)); //the 8 changes to 4 if 4 magnets are used.
      timeold = millis();
      //Serial.println(rpmcount,DEC);
      rpmcount = 0;
      Serial.println(rpm,DEC);
   }
}

AWOL

Code: [Select]
attachInterrupt(0, rpm_fun, FALLING); 
Right there, pin 2.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

James C4S

http://arduino.cc/en/Reference/AttachInterrupt
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

GoForSmoke

There's a delay(50) in the ISR. Not a good idea.

Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

Joes

o ok i see thanks for that link one problem i can see is i am using an arduino uno and i will eventually need 3 hall inputs so how will i overcome that?

Quote

There's a delay(50) in the ISR. Not a good idea.

yes there is where it is blinking the led i dont actually need that led how can i get rid of that function as ive noticed if i remove void rpm_fun() i get a error

PeterH


yes there is where it is blinking the led i dont actually need that led how can i get rid of that function as ive noticed if i remove void rpm_fun() i get a error


You could remove the blinking by taking out the two lines of code that write HIGH and LOW to the ledPin, and the delay between them.
I only provide help via the forum - please do not contact me for private consultancy.

Joes

ok so basically leave it there but take the internals out of it.

would this work or am i barking up the wrong tree?

Code: [Select]



volatile int rpmcount;
int sensorState = 0;
unsigned int rpm;
unsigned long timeold;
int rpm1 =1;


void setup() {
  Serial.begin(9600); 
pinMode(INPUT, rpm1);
}
void loop(){
 
   if(rpm1>=5) {
      rpm=(60000*rpmcount)/(8*(millis()-timeold)); //the 8 changes to 4 if 4 magnets are used.
      timeold = millis();
      //Serial.println(rpmcount,DEC);
      rpmcount = 0;
      Serial.println(rpm,DEC);
   }
}

CrossRoads

"i will eventually need 3 hall inputs so how will i overcome that?"

You can have an interrupt on any pin, they are called PCINT.
See NickGammon's writeup on them here
http://www.gammon.com.au/forum/?id=11488
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

GoForSmoke

You can keep the blinking led.
Move the blink part outside of the ISR. Set up a global byte variable and make it volatile to use as a blink flag, maybe call it bFlag. When the ISR runs, set that to 1 in the ISR. Then in loop() set up an if ( bFlag ) { } that makes the led blink and sets bFlag = 0.

So your ISR increments rpm count and flags the blink, it runs in next to nothing flat and is ready to service the next interrupt that fast.

IIRC you can set up any I/O pin to interrupt on Level Change. But look into things, maybe you don't need to use interrupts at all. Most things don't at 16 MHz.

You'd do better to learn how to use timers to run multiple tasks without using blocking code.
This is Nick Gammon's site, he's a master at explanations.
http://www.gammon.com.au/forum/?id=11411




Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

PeterH


would this work or am i barking up the wrong tree?


Wrong tree entirely. You have completely removed the interrupt handler now.

In your original sketch, this interrupt handler was called when you got a falling edge on pin 2:

Code: [Select]

void rpm_fun()
{
      rpmcount++;
      digitalWrite(ledPin, HIGH);
      delay(50);
      digitalWrite(ledPin, LOW);
}


These are the lines of code that turn ledPin HIGH, wait 50 milliseconds and then turn it LOW again:

Code: [Select]

      digitalWrite(ledPin, HIGH);
      delay(50);
      digitalWrite(ledPin, LOW);


If you take those three lines out it will no longer flash the LED and will no longer have that unwise delay() in the interrupt handler.
I only provide help via the forum - please do not contact me for private consultancy.

Joes

hi thanks for your replies on that link http://www.gammon.com.au/forum/?id=11488 there is a lot of stuff on that website to get your head wrapped around lol i have come up with this compiles fine but somethings telling me im missing something here?

Code: [Select]



volatile int rpmcount;
int sensorState = 0;
unsigned int rpm;
unsigned long timeold;


ISR (PCINT2_vect)
{
// handle pin change interrupt for D0 to D7 here
}  // end of PCINT2_vect


void setup ()
  {
  Serial.begin(9600); 
  // pin change interrupt (example for D0)
  PCMSK2 |= _BV (PCINT16);  // want pin 0
  PCIFR  |= _BV (PCIF2);   // clear any outstanding interrupts
  PCICR  |= _BV (PCIE2);   // enable pin change interrupts for D0 to D7
  }

void loop(){
 
   if(rpmcount>=5) {
      rpm=(60000*rpmcount)/(8*(millis()-timeold)); //the 8 changes to 4 if 4 magnets are used.
      timeold = millis();
      //Serial.println(rpmcount,DEC);
      rpmcount = 0;
      Serial.println(rpm,DEC);
   }
}



p.s i dont wont the led output

UKHeliBob


somethings telling me im missing something here?

How about something to update rpmcount ?
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.

Joes

Code: [Select]



volatile int rpmcount;
int sensorState = 0;
unsigned int rpm;
unsigned long timeold;


ISR (PCINT2_vect)
{
   rpmcount;
// handle pin change interrupt for D0 to D7 here
}  // end of PCINT2_vect


void setup ()
  {
  Serial.begin(9600); 
  // pin change interrupt (example for D0)
  PCMSK2 |= _BV (PCINT16);  // want pin 0
  PCIFR  |= _BV (PCIF2);   // clear any outstanding interrupts
  PCICR  |= _BV (PCIE2);   // enable pin change interrupts for D0 to D7
  }

void loop(){
 
   if(rpmcount>=5) {
      rpm=(60000*rpmcount)/(8*(millis()-timeold)); //the 8 changes to 4 if 4 magnets are used.
      timeold = millis();
      //Serial.println(rpmcount,DEC);
      rpmcount = 0;
      Serial.println(rpm,DEC);
   }
}



better?

Grumpy_Mike

Quote
better?

No try:-

Code: [Select]

rpmcount++;

PeterH

You started with a sketch that did more or less what you wanted, in a fairly simple way - no messing with hardware registers and so on.

Why have you thrown that away and started again with a more complex approach?
I only provide help via the forum - please do not contact me for private consultancy.

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