Thanks Mark and Paul,
I'll perform some tests using internal pullups, if i'll found problems i'll install external.
Will keep you updated
Pasquale
Pasquale
You can decide whether pull-ups are enabled or not when configuring each pin. See PORTn_PCRx register.
The pull-up resistors will have a wider tolerance spread than external ones though.
Regards
Mark
Hi, Longo
I agree with Mark. It is better to add external pull-up resistor. The internal resistor is a weak pull-up. So you need add a strong pull-up external to ensure communication is good on no good layout condition. Hope my reply can help you.
Best Regards
Paul