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Why does Nucleo's PA 3 terminal show 3.3 V with ADC

Ken Inoue
Associate III
Posted on July 25, 2017 at 01:56

Thank you for your patronage. 

I'm Japanese student. Sorry for my poor English.

I'm using STM32F334Nucleo.

Nucleo's PA 3 terminal indicates about 3.3 V in ADC in a situation where nothing is connected.

On the other hand, the PA0 terminal shows about 0V in the AD conversion in a situation where nothing is connected.

Why do these two differ?

0690X00000607feQAA.png0690X00000607g0QAA.png0690X00000607fZQAQ.png0690X00000607fjQAA.png0690X00000607gSQAQ.png
1 ACCEPTED SOLUTION

Accepted Solutions
Posted on July 25, 2017 at 02:49

Probably because it is connect to the VCP USART from the ST-LINK. Review the schematic

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View solution in original post

5 REPLIES 5
Posted on July 25, 2017 at 02:49

Probably because it is connect to the VCP USART from the ST-LINK. Review the schematic

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Zt Liu
Senior III
Posted on July 25, 2017 at 02:57

this is your target mcu

0690X00000607g3QAA.png

belowed is your st-link

0690X00000607g8QAA.png

you should probably removed SB13 and connect SB62

Posted on July 25, 2017 at 03:46

Or just use the pins designated for the Arduino analogue interface.

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Posted on July 25, 2017 at 06:45

Thank you for your early reply. I was able to solve this problem. I am very grateful to you.

Posted on July 25, 2017 at 06:50

Thank you for your clear explanation. Thank you for showing the solution. I am very saved because I do not have anyone familiar with the STM32 MCU in my surroundings. Thank you.