Odd behavior Duemilanove - unwanted interrupt [solved]

Something odd happens: (Duemilanove) Running this empty program: (USB power)

void setup(){} void loop(){}

Led (pin13) is repeatedly blinking twice with approx 2sec in between blinks. The sequence repeats everey 32secs.


This 32 sec also happened to disturb an ISR-rutine running 8000 times/sek (for feeding PCM sound) Ideas ? Knut, Narvik,Norway

What ISR? You said it was an empty sketch.

What have you got connected to it?

knut_ny: Something odd happens: (Duemilanove) Running this empty program: (USB power)

void setup(){} void loop(){}

Led (pin13) is repeatedly blinking twice with approx 2sec in between blinks. The sequence repeats everey 32secs.


This 32 sec also happened to disturb an ISR-rutine running 8000 times/sek (for feeding PCM sound) Ideas ? Knut, Narvik,Norway

I suspect you have a power problem or other hardware thingee going on. Why don't you place a print line statement in the setup function saying something like " I'M in the setup function" and run the serial monitor and see if it prints out every 32 seconds or just once. If so the chip is going through a reset so maybe low voltage or other hardware related cause. Scope the power 5V and then scope the reset pin, you should be able to find a root cause.

Lefty

  1. try - stille totally empty scetch.

The 32sec repeating problem disappear while serial window in open, but reappear when serial comm is closed. Do the connected PC/USB have routines tha can explain this behavior ?

Knut

knut_ny: 2. try - stille totally empty scetch.

The 32sec repeating problem disappear while serial window in open, but reappear when serial comm is closed. Do the connected PC/USB have routines tha can explain this behavior ?

Knut

Sounds like something in your PC is scanning for open comm ports every 30 seconds or so. Opening a comm port will reset an arduino board if it's plugged into the PC. Try powering your arduino board with an external DC power source and disconnect it from the PC and see if the problem does not go away.

Some PC blue tooth driver/applications scan for comm ports, if you have such try closing them.

Lefty

:) Thank you for your help. I now know that the microcontroller is disturbed by the USB-interface. Problem SOLVED