Software reset?


Maybe a silly question, but is it possible to perform a software reset on the Industruino ?

I did find the following routine which seems to reset the harware but when my program starts it behaves in a different manner.

asm volatile ("  jmp 0");

Something is not quiet right but I'm not sure what..



Gary Lowe
Gary Lowe
| 1 1 2
Asked on 3/11/17, 3:43 PM

Thanks Stefano, Tom.

My program uses interrupts on CH1, CH2 and CH3 and timing is critical as I need to measure the time between inputs..

Would using the watchdog cause any unecessary delays ?



Gary Lowe
on 3/15/17, 4:46 PM

The watchdog is an hardware timer that needs resetting before it overlaps, otherwise it will reset the machine. The only thing wdt_reset() does is write a zero in a register. You can put your wdt_reset() wherever you like, as long as it gets called at least every 4 seconds. My solution is to do it when Enter is not pressed, so when I keep the Enter button pressed for more than four seconds the machine restarts.

Stefano Giuseppe Bonvini
on 3/15/17, 4:52 PM

Okay. Thanks Stafano..

Gary Lowe
on 3/15/17, 5:00 PM

Hello Gary,
here is how I do it in my projects.
I use Watchdog timer reset.

So first include the watchdog library:

#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/wdt.h>

Then setup the Watchdog in setup():

void loop() 

  //Enable WDT timer
  wdt_enable(8);                                 //This is equal to WTDO_4S, which is available on AT90USB1286 but probably not reported in wdt.h file
​  }

Then I put this line at the beginning of ReadButtons():

  buttonEnterState = !digitalRead(buttonEnterPin);
  buttonUpState = !digitalRead(buttonUpPin);
  buttonDownState = !digitalRead(buttonDownPin);

  //Reset WDT if Enter not pressed
  //After 8 seconds machine will reset (actually 4)
  //Also in case it hangs for other reasons
  if(buttonEnterState == LOW) wdt_reset();

So if you press the Enter key for more than 4 seconds, the machine will reset.
Hope this is useful!

Stefano Giuseppe Bonvini
Stefano Giuseppe Bonvini
| 2 0 2
Answered on 3/13/17, 10:41 AM

Hi Gary,

The most reliable way to do this is through the hardware watchdog timer. Another way is defining the function

void (*resetFunc)(void) = 0;

but that does not do a full restart (documented elsewher).

You can read more about watchdog timers at (sorry for formatting issues)

| 1 1 3
Answered on 3/12/17, 11:53 PM

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Asked: 3/11/17, 3:43 PM
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Last updated: 3/15/17, 5:00 PM