attachInterrupt calls dozens of times one pulse

Forum 2005-2010 (read only) Hardware Interfacing
1

I'm using pins 4,5 for newSoftserial and 3 for the interruption 1 in one Arduino duemilenove board.

I need to detect a pulse that has a regular duration (0,18s) the problem is that the function associated to the interruption is called dozens of times by each pulse (30 - 70).

I tested all the possible configurations and only attachInterrupt(1,count,LOW) works in the described way , the rest (CHANGE, FALLING, RISING) call the count function without stop from the resetting of the Arduino board and even without any pulse.

I need to count the number of pulses but each time I detect several ones.
Could this be due to the using of the NewSoftSerial Library?

Do you know another way to make this counting without the using of interruptions? (The period between pulses can not be known in advance, depends on user actions)

2

I tested all the possible configurations and only attachInterrupt(1,count,LOW) works in the described way ,

That is why it is being called many time, it is being called on a level and when the ISR returns your input is still at that level so it gets called again. You want one of the edge modes.

It sounds like the serial library is also using interrupts and it is clashing with what you want to do. Try sorting out the interrupts before you add in the library so you can tell if it is your code or the library.

3

Thanks.
I understand the prb with the LOW calling. For the debugging my prb is that, in order to have the pulse, I need to use the Serial library (only while there's serial communication I've the pulse) . The function I call is very simple only print a string to see it if was detected.

Do you know if there's another way to control this pulse counting using the serial library?

4

Sorry I can't understand what you are saying. What is a prb? and why do you need the serial library to generate a pulse that fires your ISR?

5

I just made a modification in the code using also detachInterrupt. I searched for a place where there's a delay (it seems enough to wait the detection) and I only active the interrupt at the beginning and "detach" at the end. Now it works with FALLING detection . I know this solution is not very "clean" but it works by now

6

@ Grumpy_Mike : The pulse is only generated periodically by the device I'm reading after sending an activation code with the serial interface (using newsoftserial) , without the library I can not send the command and start receiving the pulses

7

OK that makes more sense.
However, for debugging you can just put a push button on the pulse input to test it out.