Dear Sir,

Once a request is answered it is always closed, then when the customer answer it is automatically re opened again.

By using your program I am not able to recreate this issue with either ATtiny2313, ATtiny23 or ATtiny25. They all behave they way they should regardless of the clock frequency or if the CKDIV8 fuse is enabled or not. And I see no jitter at all. I have attached a screen shot from my measurements.

Best Regards,
Ivar Holand
AVR General Support
Atmel Technical Support Team

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Вот что я ему посылал:

Dear Mr. Holand,

Please find attached the thorougly commented code example. I have emailed the same to avr@atmel.com earlier today. BTW, I wonder why my request is now marked as "closed"?

Best regards

MBedder

;________________________________________________________________________________

.nolist
.include	"tn2313def.inc"
.list

;-------------------------------------------------------------------------------
WDT_off:
; Watchdog reset
	wdr					; __watchdog_reset();

; Clear WDRF in MCUSR
	in	r16,MCUSR			; MCUSR &= ~(1 << WDRF);
	andi	r16,~(1 << WDRF)
	out	MCUSR,r16

; Write logical one to WDCE and WDE
	in	r16,WDTCSR			; WDTCSR |= (1<<WDCE) | (1<<WDE);
	ori	r16,(1 << WDCE) | (1 << WDE)
	out	WDTCSR,r16

; Turn off WDT
	clr	r16				; WDTCSR = 0;
	out	WDTCSR,r16
;-------------------------------------------------------------------------------

main:		; void main (void){
	ldi	r16,0xFF			; DDRB = 0xFF;
	out	DDRB,r16

	ldi	r16,0xFF			; char temp1 = 0xFF;
	ldi	r17,0				; char temp2 = 0;

loop:					; while (1){
	out	PORTB,r16			; PORTB = temp1;
	out	PORTB,r17			; PORTB = temp2;

	rjmp	loop				;  }
	
.exit				; }

;________________________________________________________________________________

With an internal RC oscillator (both 4 or 8 MHz) the code runs as expected only when the CKDIV8 fuse is programmed.
When the CKDIV8 is not programmed AND the BOD is off (BODLEVEL = 7) the port toggle frequency observed with a scope
looks like not stable (very large jitter). When the BOD is turned ON (BODLEVEL = 4..6) the port toggle frequency is
interrupted for relatively long time periods which depend on the SUT setting(!).

I am professionally working with AVRs for many years, but I've never seen that behaviour before.

Please do not hesitate to contact me when necessary - I am very interested in solving that issue - as well as my
colleagues engineers too.

Best regards

MBedder