Hi,
I don't think there is any connection between TMR0 and RA4 unless you use
RA4 as
T0CKI (Timer0 with external clock pulses) by setting T0CS in OPTION_REG.

I guess that is what you mean. With a 20 Mhz clock, I'd suggest that you
keep it as low as possible. But it !must! be <= (lesser than or equal to) 4
Mhz (20Mhz /4) . The higher the
external frequency, the harder will it be for the PIC to synchronize its
TMR0 reg with it.

Regards,

Jeethu Rao

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Aart
Sent: Saturday, June 23, 2001 7:50 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: Timer0 Interrupt, maximum frequency.


Hi,

has anybody an idea what will be the maximum freqency on RA4 if i use it as
input? With a 20 Mhz Clock (16F84A).

Thx, Aart.

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