What can cause the digital output (voltage level) to be way lower than 3.3V (Note: VCC of the MCU = 3.3V)?

[NElsa.1]

Hello everyone,

I'm using STM32F429 MCU (STM32F429I-DISC1 board). I was generating PWM signals on PA1, PA2,PA3 and PA5 using TIM2 ... The important part is that the PWM signals on PA3 & PA5 are fine where the high digital state is at 3.3V. For PA1 & PA2 , the PWM signals have digital high state at 650mV !? ... I attached a picture to show the PWM (on PA3) and the PWM (on PA1)

I also tried to make PA1 as an output with an open drain and a pull-up resistor ... when I give it high state ... the output voltage of the pin is 0V .... The pin is acting as if there is some kind of a medium pull-down resistance.

Does this mean that these 2 pins are damaged?

(Note: this is not a probe or oscilloscope problem ... I measured the digital high state with a voltmeter as well)

Thanks

Nour

[TDK]

Probably those pins are used by something else on the board which is fighting for control of the voltage.

[TDK · Accepted solution]

Yep, those are connected to the L3GD20 onboard gyro.