topic GPIO restrictions on XTAL / EXTAL in Kinetis Microcontrollers

GPIO restrictions on XTAL / EXTAL

mjbcswitzerland — Thu, 14 Jul 2011 16:52:26 GMT

Hi All

K60 user's manual 10.2.3 Signal Multiplexing Constraints

"The following signals have general purpose output capability only (no general purpose input):

- PTA18/EXTAL

- PTA19/XTAL"

On the K60 tower board PTA19 is connected to Switch 1.

When the port is configured as GPIO input the switch value seems to be able to be read as expected. (PGPIO_PDIRA bit 0x00080000 when switch is not pressed and 0x00000000 when the switch is pressed).

Question - is there a restriction to this pin or is the user's guide at fault???

Regards

Mark

Re: GPIO restrictions on XTAL / EXTAL

anthony_huereca — Fri, 15 Jul 2011 01:57:58 GMT

Older revisions of the RM mention that incorrectly. The lastest revision (Rev5) does not list that constraint.

-AMH

Re: GPIO restrictions on XTAL / EXTAL

mjbcswitzerland — Fri, 15 Jul 2011 18:12:57 GMT

Thanks - was still using Rev. 4 for the K60. New versions of all manuals don't mention it so assumed not an issue.

Regards

Mark

Re: GPIO restrictions on XTAL / EXTAL

egoodii — Tue, 23 Aug 2011 00:11:13 GMT

Note that there IS an errate 3402 against PTA19 -- fights with CLKO functions if ERCLKEN is set. I have an unconfirmed suspicion that if RANGE=0 this cross-tie is 'weak'.