GPIO Slew Rate and Pull Resistor for KL03

McLuhan — Mon, 19 Apr 2021 08:24:34 GMT

I'm trying to setup the outputs for the microcontroller MKL03Z32VFK4 in MCUXpresso (my first project).

I found that the slew rate of the output is different. One output has a slow slew rate, the others are fast.

I'm aware that it is not possible to change this settings, as described by the manual of the MCU.

Since I need to sync these outputs, it could be possible to compensate this timing difference via software, anticipating the activation of PTA3?

Slow slew rate should mean max 36 ns

Fast slew rate should mean max 25 ns

So activating PTA4 and PTA5 after 9 ns the activation of PTA3 should work fine.

Another question is related to the pull resistor configuration.

I would like that the port is connected to GND when it is not active.

Do you confirm that I have to select the pulldown resistor and enable it?

Thank you for your help.

Re: GPIO Slew Rate and Pull Resistor for KL03

jingpan — Tue, 20 Apr 2021 08:00:55 GMT

Hi McLuhan,

KL03 maximum speed is 48Mhz. That means each instruction need 20ns. I think it is difficult to compensate this by software even you use FGPIO.

You can set unused pin to input mode and enable the pull down resistor. If pull function is disabled, the pin is in floating state.

Regards,

Jing