Cannot access >=3,3V at GPIOA - STM32F411

[timbo2023]

Dear Ladies and Gentlemen,

for you it is your daily business - for me as customer a contemporary challenge:

Something went wrong with my pin-configuration.

I measure ~1,7 V as GPIO-output of Port A instead of wished >=3.3 V.

My power supply is a USB.

Could you give a sample pin configuration for (3.3 V output) of Port A in discussion?

As additional comment:

Round about 5 V are present at the 5 V-Pin(s).

Thank you in advance.

TIMBO

[timbo2023]

I thought 3.6 V are possible?

PA0 ~ 1.7 V  (?!?)

PA1 ~ 3.2 V

PA2 ~ 3.2 V

PA3 ~ 3.2 V

The 5V-pin, are there any access?

[SofLit]

If PA0 is connected to something (as shown by your photo), please disconnect it and let it floating and measure the voltage level on this pin. If it goes to 3.3V it does mean there is something wrong on the other side forcing the pin to go to 1.7V!

3.2V level as output pin is correct.

[timbo2023]

?! ok ?!

I just thought that I red something to connect ADC-devices to get the "full" 4.x V USB-power...from the 5 V-pin, too.

[timbo2023]

Is it possible to get the "full" USB Power on a pin?!

[SofLit]

You didn't answer any of our questions and you continue to ask more.. Sorry no one can help you that way!

[timbo2023]

Attached - my situation ...

My aim is to have at least 3.3 - or more - voltage on PA0 ...

[SofLit]

My answers:

1. Disconnect any load from PA0 for test
2. Use the HAL as I suggested previously and try to toggle PA0.. If it does work and you reach 3.3V move to the direct access to registers like you do. If you still at 1.7V using HAL I suspect an issue on PA0 pin. So change the MCU or the board. You're using BlackPill: I cannot consider it's something guaranteed!

To have more than 3.3V as output:

• Use a voltage level shifter as suggested by AScha.3 
• Or configure the pin in open drain and connect a pull-up resistor between the pin and 5V. The pin must be five volt tolerant: FT). But here you need to take care about the slopes of your signal you need to output on the pin and the load to connect to it.

Hope it does answer your question.

[timbo2023]

very tough - SofLit and - in look to the separate solution - Ascha.3

I will try both suggested solutions and compare it in a more scientifically way in the future...

But for now, that was my actual discussion aim for today:

"configure the pin in open drain and connect a pull-up resistor between the pin and 5V. The pin must be five volt tolerant: FT). But here you need to take care about the slopes of your signal you need to output on the pin and the load to connect to it."

Is it possible to get for this case - a bare metal snippet in look to the A-Pin configuration?

Thank you in advance for your "input"...

[timbo2023]

@AScha.3 

Are you expert in look to an external motivated solution in amplifying signals in this "voltage size"?

I have an operational amplifier MCP6002 with an external voltage source of 9V (block) at home.

When I use this operational amplifier as non-inverted amplifier, is it possible to realize an amplification in this "size" and in an external circle?

[timbo2023]

What actually is the big episode with the "schottky-diode"-solutions?!

Is that relevant for this topic, too?