GPIO Problem

[changhyunkim]

Hello, I am having an issue with the STM32 GPIO. The problem is that immediately after supplying power to the chip, GPIOs such as PJ0, PJ1, PJ2, etc. are momentarily powered, behaving as if they were set as outputs.

Below is the test sequence:

1. I created the project without setting the GPIOs and then performed program verification on the chip.
2. I turned the chip off and then back on.
3. I monitored the power supply line of the chip and specific GPIO using an oscilloscope.
4. The result showed that when the power supply voltage increased to above 1.7V, the GPIO voltage also increased.

I hope this helps!

[TDK · Accepted solution]

Are the pins connected to anything? If not, don't assign any significance to pins that are floating. They can be influenced by any number of things, including cross-talk on the board.

If you need pins to have a defined state at reset, use an external pullup or pulldown.

[changhyunkim]

Thank you, TDK

We are used a output pin. But, nothing a external pullup or pulldown.