100MHz frequency counter

[pierlu]

I think the code is OK.

start
	bsf STATUS,RP0			; Set tmr0 as counter
	movlw b'11100111'		; on rising edge with 1:255 prescaler.
	movwf OPTION_REG		;
	bcf TRISA,2				; Set tmr0_pin as output.
	bcf STATUS,RP0			;

	clrf TMR0

	call toggletest

	goto start

toggletest
	movf TMR0,W
	movwf temp
	clrf count

toggle
	incf count,F
	bsf STATUS,RP0
	bsf OPTION_REG,T0SE
	bcf OPTION_REG,T0SE
	bcf STATUS,RP0

	movf TMR0,W
	subwf temp,W

	btfsc STATUS,Z
	goto toggle

	comf count,F
	incf count,F
	return

When I'll have a real pic I will try again. For now using T0CS instead is good for me.

Thank you.

Bye.

 

[Mike - K8LH]

You're setting the RA2 pin as an output. Is that the T0CKI pin for the PIC source code you're testing? T0CKI is on the RA4 pin on some PICs.

Mike

<added>

I see now that your 16F630 has T0CKI on RA2...

 

[vsmGuy]

Did toggling the T0SE from firmware increment the prescaler?

If so - this means we would need to have only the TMR0 pin connected to sample the signal leaving all other pins free!

 

[Mike - K8LH]

Did toggling the T0SE from firmware increment the prescaler?

If so - this means we would need to have only the TMR0 pin connected to sample the signal leaving all other pins free!

It does increment the prescaler but I doubt if that "feature" was ever intended and so it doesn't surprise me that the Simulator doesn't know about it (LOL)...

 

[vsmGuy]

Makes sense

Di you try this out in a simulator?

I am thinking of using TIMER1 in asynch mode - any working samples in C to read/start from?