Re: [avr-chat] avrdude : chip not responding

[Erik Christiansen]

On Fri, Sep 02, 2005 at 08:15:05AM +0200, Vincent Trouilliez wrote:
> I am thinking of adding Schmitt trigger buffers, but I have only TTL
> (74LS), chips and at 125KHz, with no load or at a light (150Kohms)
> resistive load, the high-level is nearer 4V than 5V, so I am unsure if
> the AVR will reliably (if at all !) consider this as a valid signal !
> Worse case, it will damage the input ! :-/
> Must check the datasheet again...

With Vcc == 5v, you'll have 1v margin with Vin == 4v, so no problem.
(If you ever have a need to, you can add 1k pull-ups to the 74LS
outputs, to drive to Vcc at moderate speeds.)

I wouldn't worry too much about a little rosin residue. It doesn't
conduct that well. How bad is the crosstalk on the long cable when the
chip _is_ connected? ;-)

Erik