STM32L071CBT6 issue While recieving Input for GPIO pin

[Hema_56]

 

STM32L071CBT6 GPIO PB15 Input Not Responding to 5V Signal from Buck Converter

Hello everyone,

I'm using the STM32L071CBT6 microcontroller and facing an issue with reading a digital input on GPIO pin PB15.

What I'm Trying to Do:

I’m using a buck converter with a 5V output to indicate the power status. The 5V output from the buck converter is connected to PB15, which is configured as a digital input on the STM32.

 

Setup:

• Buck converter 5V output = GPIO PB15

• Measured with multimeter: PB15 shows 5V when buck converter is ON

• PB15 is configured in firmware as an input pin (floating or pull-down)

Problem:

Although PB15 is reading 5V on the pin when measured, the firmware logic that depends on PB15 being HIGH doesn't work.

 

What I’ve Checked:

• The GPIO pin is correctly configured as input

• Measured 5V directly at PB15

• Tried enabling internal pull-down or external pull-down resistor

• No response or logic change in the code when the 5V signal is applied

Why does PB15 show 5V physically (confirmed via multimeter) but the STM32L071 doesn't detect it as a logic HIGH in firmware?

[TDK]

Set it as an output and drive it high and verify that (a) the voltage goes high and (b) the IDR register reflects this.

 

Related/duplicate? Just a coincidence you two asked the same uncommon question?

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