hi, dears.
I have a question about the pins that unused in microcontrollers.
I want to link all of them to each other directly and pull down them via a 100 ohms resistor. can direct linking of IOs make problems in my design?
notice you that all IOs are input by default and I let them still in this situation.
are there any better ways to protect my microcontroller and circuits from noise in industrial areas?
thank you

 

If the ports are always configured as input, shorting them and using a single pull down resistor is fine. I'd suggest using a more sane resistor value of 10k.

Your microcontroller may have configurable inputs (i.e. internal pull down or pull up resistors).

 

If mains powered, i.e. non battery supply, then you could also look at earth grounding P.S. commons to service GND.
Max.

 

Why leave them as inputs? Configure as outputs. Less wiring, fewer components, and easily changed, if needed.

 

hi, dears.
I have a question about the pins that unused in microcontrollers.
I want to link all of them to each other directly and pull down them via a 100 ohms resistor. can direct linking of IOs make problems in my design?
notice you that all IOs are input by default and I let them still in this situation.
are there any better ways to protect my microcontroller and circuits from noise in industrial areas?
thank you

That depends on the chip's particular architecture. I.e. I like to configure the unused pins of the at89lp4052 as bi-dir i/o, which activates an internal weak pull-up and minimizes the use of external components. Whilst at the same time gives the pin a clearly defined state, and is not just left floating.

On the other hand, the pic architecture, in particular the pic10 family, recommends a different setup for unused pins, to minimize power draw.

The concrete answer to your question is actually device-dependent.

 

Would some of the pins do "weird" stuff on power up/power reset?

 

thank you all.

Would some of the pins do "weird" stuff on power up/power reset?

could you explain more?

 

Would some of the pins do "weird" stuff on power up/power reset?

Depends on the family and vendor. That has been a problem in the past, most
processors today guarantee GPIO state. Read the fine print in the tech manuals.

Regards, Dana.