ColdFire/68K Microcontrollers and ProcessorsのトピックRe: Do MCF51JM have schmitt-trigger inputs?

Do MCF51JM have schmitt-trigger inputs?

celsoken — Thu, 19 Nov 2009 05:51:20 GMT

It sounds like a stupid question but I could not find in Coldfire V1 documentation any reference to schmitt-trigger inputs. In fact the word schmitt is not found at all. I'd like to save some schmitt ports...

Thanks for any hints,

Celso

Re: Do MCF51JM have schmitt-trigger inputs?

TomE — Fri, 20 Nov 2009 06:07:02 GMT

My first port of call was the MCF51JM data sheet:

http://www.freescale.com/files/32bit/doc/data_sheet/MCF51JM128.pdf?fpsp=1

Check the Vih and Vil figures, and Table 10 also gives:

Table 10: "DC Characteristics".

Input hysteresis; all digital inputs Vhys: 0.06 x Vdd

So now we know Freescale uses the keyword "Hysteresis", search for that and find within the first few pages:

1.3.1 Feature List

• Input/Output
— 66 GPIOs
— Eight keyboard interrupt pins with selectable polarity
— Hysteresis and configurable pull-up device on all input pins; configurable slew rate and drive strength on all output pins

Re: Do MCF51JM have schmitt-trigger inputs?

celsoken — Fri, 20 Nov 2009 07:13:14 GMT

Thanks TomE,

I owe U some beers.

Cheers,

Celso