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GPIO after reset value

Hi everyone,

First of all thanks for your answers and sorry for my english level.

I checked the reference manual of my MCU (RM0468) and I realized that the after reset value of the most GPIO is high impedance.

I need to stablish a new after reset value in some of GPIOs because I am controlling some mosfets and sometimes they switch with the MCU reset. I have tried to configure the pull-down resistor of the GPIOs but my problem is still happening because my code takes some time to execute.

My question is: How can I stablish a new after reset value of a GPIO? I have read that there are a locking system but I dont understand how it works. Any Idea?

Thank you very much

4 REPLIES 4

External pull-up/pull-down resistors.

The GPIO pins reset to inputs and there is always a time between power up and programming the GPIO pins as outputs in a particular state. You'll have to use external resistors to bridge this startup time.

S.Ma
Principal

Some specifc pins have permanent pull up/down such as JTAG pins, here might be handy....

It doesnt work.

GPIOs sometimes start with 3V3 and sometimes with 0V. High impedance is unpredictable. The pull-up and pull-down external resistors doesnt work because I can use, for example, a pull-down resistor, but the GPIO start with 3V3 and my mosfet switch after reset.

You are misunderstanding the basics of electronics. High impedance doesn't push or pull any significant current and therefore will not force the pin to any specific level.