8-bit Microcontrollers中的主题 Re: TPM2CLK Input Not Getting Pulled Up (AC32)

TPM2CLK Input Not Getting Pulled Up (AC32)

Luigi — Wed, 30 Sep 2009 04:22:38 GMT

I am using an 'AC32 part and want to use an external clock source for TPM2. I have an open collector driver currently driving that port pin (PTD4/TPM2CLK/AD1P12) and it is pulled up internally. When used just as an input port with the internal pull-up enabled, it works fine (i.e. the pullup works). When used as an external clock input, the pull-up does not seem to be there.

The manual states, "When any pin associated with the timer is configured as a timer input, a passive pullup can be enabled." That sounds like my pull-up should work. My internal pull-up is still enabled, but it does not pull the pin high when configured as TPM2CLK. Any clues?

Lou

Re: TPM2CLK Input Not Getting Pulled Up (AC32)

ThaManJD — Tue, 06 Oct 2009 13:40:46 GMT

I'm pretty sure the manual is referring to the timer channels (for input compare) and not the external timer clock input. If that is a direct quote from a manual then i would agree that the phrase is misleading.

The current ACxx manual appears to be a little bit clearer in this description.

Re: TPM2CLK Input Not Getting Pulled Up (AC32)

Luigi — Thu, 08 Oct 2009 19:46:51 GMT

I finally got the answer from my Freescale rep who contacted the factory. It is as you say. The timer "inputs" as they say that still have pull-ups enabled are only those used when doing capture. The documentation is VERY misleading and should be changed. Thanks for the reply.

Re: TPM2CLK Input Not Getting Pulled Up (AC32)

J2MEJediMaster — Fri, 09 Oct 2009 20:39:02 GMT

What is the exact name of the Freescale document you were using that was not clear on the subject? I am trying to report this problem so that it can be fixed and prevent this from happening in the future.

---Tom

Re: TPM2CLK Input Not Getting Pulled Up (AC32)

Luigi — Thu, 22 Oct 2009 02:35:39 GMT

Sorry for the delay in getting back to you. On both the front and back of the document it says, "MC9S08AW60, Rev 2 12/2006". Thanks for reporting it.

Lou