topic Re: GPIO DC/AC timing parameters in Schmitt trigger mode in i.MX Processors

GPIO DC/AC timing parameters in Schmitt trigger mode

ko-hey — Wed, 26 Aug 2015 05:23:17 GMT

Hi all

I have question about GPIO specification.

I doubt that the DC/AC timing parameters are different.

Because the behavior is different in CMOS mode and Schmitt trigger mode in my board.

So I want to confirm the following.

Does the DC parameter that is shown in P39 of IMX6SDLAEC is for CMOS mode ?

Are there any different DC and AC parameter in CMOS mode and schmitt trigger mode ?

In my understanding, i.MX becomes slower to recognize a "high" level in schmitt trigger mode than CMOS mode.

Because of the delay, is there possibility that i.MX can't latch the data correctly ?

ko-hey

igorpadykov — Wed, 26 Aug 2015 07:59:26 GMT

Hi ko-hey

1. yes

2. with schmitt input hysteresis enabled, trigger may be later than

without hysteresis, because additional time is needed for signal

to reach hysteresis level. For example without hysteresis enabled

typical trigger level 0.5*OVDD, with hysteresis enabled it will be

0.5*OVDD + hysteresis value. According to Footnote 3 :

Hysteresis of 250 mV is guaranteed over all operating conditions when hysteresis is enabled.

3. yes this is correct understanding.

>Because of the delay, is there possibility that i.MX can't latch the data correctly ?

no.

Best regards

igor

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ko-hey — Wed, 26 Aug 2015 08:56:32 GMT

Hi Igor

Let me confirm about question No.3.

You mean that i.MX may fail latching a data.

Is it correct ?

ko-hey

igorpadykov — Wed, 26 Aug 2015 09:03:59 GMT

Hi ko-hey

no, meaning that i.MX will not fail latching a data.

Best regards

igor