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STM32 GPIO pin small output voltage

JS8
Senior

Hi,

I am switching PB12 on/off with 1 second delay on STM32F030C8T6. Measuring with the multimeter, the HIGH state is only 0.2 volts, even though Vdd is 3.3V. I have turned off all things that could be drawing too much power from the MCU. Other pins output a voltage very near 3.3V. There are no external connections with PB12, only a 10k pull-up resistor. What could be causing this?

1 ACCEPTED SOLUTION

Accepted Solutions

Hi,

I forgot that yesterday I accidentally shorted the pin to 38V for a little moment and a little bit of smoke came out. That is probably it. 

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4 REPLIES 4
TDK
Guru

If there truly is nothing connected to it, and the code is correct, then the hardware is likely damaged. Nothing special or unique about PB12.

Custom hardware? No solder bridges or other shorts? Does current consumption on the chip go up when you try to set PB12 high?

You can check the ODR and IDR bits in GPIOB. If ODR is high and IDR is low, that would indicate an issue.

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AScha.3
Chief

Hi,

Sure, you set PB12 to push-pull output ? + not open collector/drain ?

Then probably you damaged the pin (by short or static discharge ). Replace cpu, if need this pin absolutely.

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Hi,

I forgot that yesterday I accidentally shorted the pin to 38V for a little moment and a little bit of smoke came out. That is probably it. 

Yep, that'll do it. Pretty cool that the chip is that robust enough to still mostly work, minus the bad pin, despite a short to 38V.

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