AVR-Chat

----- Original Message ----- 
From: Dave VanHorn
To: AVR-Chat@yahoogroups.com ; AVR-Chat@yahoogroups.com
Sent: Tuesday, March 01, 2005 11:22 PM
Subject: Re: [AVR-Chat] Prototypitis


At 05:58 PM 3/1/2005, John Samperi wrote:

>At 09:50 AM 2/03/2005, you wrote:
>
> >Hmm.. I only have three of the 128Ls in hand.
> >This is a 3V app.
>
>Can you raise the voltage (5v?) for testing purposes.
>Maybe a border case chip??? (scary thought)
>
>I think I better go and do some work....but this is so
>interesting...I know, I must be leading a boring life :-)

Got it, at least the first half.
Genuine HomerCode(tm)

The vector table needs to be JMPs, not Rjmps, as the JMPs are 4 bytes, and
Rjmp is two.
Which means that the int that's been driving me nuts is really T0OV.

That's good because I need T00V, but bad because T0 is running impossibly 
fast.
With the three bits set for prescale select, I've seen TCNT0 jump from A4
to 7F in ONE instruction.
Resetting the prescaler isn't helping, and it seems that any prescaler
value results in the same thing, wether I do it in code, or clicking the
bits in the ice.
When this is happening, it's virtually guaranteed that the T0OV flag will
be set when I exit the ISR.

I've just had a Tiny11 prototype behaving very oddly. I wasted a lot of time 
with it, and then tried cleaning the flux off off the board (I often don't 
bother with prototypes). It immediately started working properly.

Leon
--
Leon Heller, G1HSM
http://www.geocities.com/leon_heller



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