S12 / MagniV MicrocontrollersのトピックRe: Leaving input capture pin floating when not in use

Leaving input capture pin floating when not in use

gator — Fri, 01 Sep 2017 19:23:30 GMT

I'm wondering if there are any negative consequences of having an input capture pin floating as long as the input capture interrupt is not enabled. I won't be using the pin when it's in this state, I'm just wondering if this could cause problems.

Thanks

Re: Leaving input capture pin floating when not in use

lama — Sun, 03 Sep 2017 17:14:42 GMT

Hi,

No there i no problem if you use it in the IC mode as well as in the OC mode when no action is selected or when selected action will not affect anything. The input logic behaves on the basis of the TCTL3/4 registers setup. Read TCTL3/4 registers and TCTL1/2 registers. I can't see MCU number to be more specific but it is common feature.... you can disable capture in IC mode and action on output pin in OC mode.

Plus, please read more info for

http://www.nxp.com/docs/en/application-note/AN5207.pdf

and

http://www.nxp.com/docs/en/application-note/AN3262.pdf

search for "unused" keyword.

If this does not answer your question(s), or I have forgotten something, or if you need more assistance, please contact me again.

Best Regards, Ladislav

Re: Leaving input capture pin floating when not in use

gator — Wed, 06 Sep 2017 13:31:36 GMT

Sorry, I forgot to mention the MCU we are working with is the MC9S12DP512. Does that change anything?

Thank you

Re: Leaving input capture pin floating when not in use

lama — Thu, 07 Sep 2017 09:51:20 GMT

Hi,

the same considerations. Probably slide 24 add some info. ... setting internal pull up requires no additional HW and it solves your issues.

Best regards,

Ladislav