Help needed for understanding some code WDT ATTiny85

Projects Programming
1

Hello,

I'm trying to use WDT reset on a ATTINY85.
For the moment it works with interrupts using the code below (setup WDT).
Because I don't understand the complete code, I'm not able to change it from interrupt to reset.
(want the ATTINY to reset when the cpu stops (8s))

==> from WDE & WDIE 1 to WDE 1 & WDIE0

Writing WDTCSR binairy (B00111001 or B00101001) don't work.

Can some help me out?

Thanks

  uint8_t bb;
  if (ii > 9 ) ii=9;   //say ii = 9
  bb=ii & 7;  // bit wise 9 AND 7 ==> B00000001
  if (ii > 7) bb|= (1<<5); // Bit wise OR==> B000100001


  bb|= (1<<WDCE);   //[u]I don't understand what happens here??[/u] B00110001 ??



  MCUSR &= ~(1<<WDRF);  //bit wise AND NOT???

  // start timed sequence
  WDTCSR |= (1<<WDCE) | (1<<WDE);  //setting WDCE and WDE to one

  // set new watchdog timeout value
  WDTCSR = bb; // played around with binairy values but didn't work

  WDTCSR |= _BV(WDIE); //also lost here  :o
2

If you edit your Original Post and add the words " WDT on Attiny85" to the title then people with expertise will be more likely to respond.

...R

3

It's great to understand how to work with the registers but the AVR toolchain does come with a useful library that makes it easy to configure the WDT:

#include <avr/wdt.h>  // Include the avr-libc Watchdog timer handling library

void setup() {
  wdt_enable(WDTO_8S);  // Set watchdog timeout to 8 seconds
}

void loop() {
  wdt_reset();  // Reset the watchdog timer
}

Reference:
http://www.nongnu.org/avr-libc/user-manual/group__avr__watchdog.html

That should make your code more portable to any model AVR since sometimes the register names are different from one chip to another. The exception is that some of the timeout durations are not available on all chips (details at the link above).

4

Download Atmel Microcontroller used in the Arduino board the you use, and search for the two registers

" MCUSR and WDTCSR "

The answar is lying there.

5

Robin2:
If you edit your Original Post and add the words " WDT on Attiny85" to the title then people with expertise will be more likely to respond.

...R

Done. Thanks for the remark

6

It works with using the code from that site. Thanks.

Still in the dark about the syntax used in my example code..

pert:
It's great to understand how to work with the registers but the AVR toolchain does come with a useful library that makes it easy to configure the WDT:

#include <avr/wdt.h>  // Include the avr-libc Watchdog timer handling library

void setup() {
  wdt_enable(WDTO_8S);  // Set watchdog timeout to 8 seconds
}

void loop() {
  wdt_reset();  // Reset the watchdog timer
}



Reference:
http://www.nongnu.org/avr-libc/user-manual/group__avr__watchdog.html

That should make your code more portable to any model AVR since sometimes the register names are different from one chip to another. The exception is that some of the timeout durations are not available on all chips (details at the link above).