STM32H743VG Pin PC2_C and PC3_C

[CBerg]

Hello folks!

The STM32H743VC Processor has two pins, that have a "_C" at the end of the name:

Pin 17: "PC2_C" and Pin 18: "PC3_C"

When I want to know what the C means, the Datasheet  says: refer to the reference manual.

DS12110 Rev 10 - page 67 - Pin Description, Footnote (6) on Pin 17 and 18:

There is a direct path between Pxy_C and Pxy pins/balls, through an analog switch. 
Pxy alternate functions are available on Pxy_C when the analog switch is closed. 
The analog switch is configured through a SYSCFG register. Refer to the product 
reference manual for a detailed description of the switch configuration bits.

The Reference Manual tells me, that I can close an analog switch

RM0433 Rev 8 - Chapter 12.3.1 - Page 548+: (for PC2_C):

This bit controls the analog switch between PC2 and PC2_C (dual pad)
0: Analog switch closed (pads are connected through the analog switch)
1: Analog switch open (2 separated pads)

But there is no further information, where this connection goes to. I have no additional Pin "PC2" on the H743.

Has that something to do with the analog input channels or is that something that is set automatically by CubeMX according to the alternative function I select on that pin?

If someone could me point to that section in the manual where it's explained what that does and how I sould address that?

Thanks!

[Andrew Neil]

https://community.st.com/t5/stm32-mcus-products/confusion-about-c-pins-pa0-c-behavior-and-functionality/m-p/787244

[CBerg]

that was quick! Thank you!

I did not find that topic when I was searching the forums for that. Thanks for beein my "human forum search consultant"

[CBerg]

Ok, thanks for the link, I now also found the section in the Reference manaual.

Next Problem: I still am not sure, what this is good for.

Does that mean that I can connect PC2 and PC3 DIRECTLY to the ADC3 (in my case), WITHOUT sending the signal though the "normal" input circuitry?

And where are the Pins / Pads without the "C" at the end? I don't have a "PC2" or "PC3" pin on the H732VG where I could establish a connection to with the "PCx_C" pin?

Sorry if this question might seem ***, but that explanation in the manual is pretty confusing.

[mƎALLEm]

Hello @CBerg ,

See also this article as it may provide you more visibility on PXY_C pins.

[CBerg]

ok, thanks for that link.

This means in my configuration: i do not have to care.

As there is no (e.g.) PC2 Pin, but only a PC2_C pin, and according to the link you gave me, if there is no PCx pin, and only a PCx_C Pin the analog switch is closed by default. And that's what I want because if t were open, the IO would be connected to "nothing" and without function.

Is this correct?

In my Particular Case RUN_ENA (PC2_C) is an open drain GPIO. I should be able to use that pin in that configuration without have to care about the SYSCFG Register settings, as i am just using the default configuration.

[mƎALLEm · Accepted solution]

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@CBerg wrote:

ok, thanks for that link.

This means in my configuration: i do not have to care.

As there is no (e.g.) PC2 Pin, but only a PC2_C pin, and according to the link you gave me, if there is no PCx pin, and only a PCx_C Pin the analog switch is closed by default. And that's what I want because if t were open, the IO would be connected to "nothing" and without function.

Is this correct?

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Yes that's correct. Otherwise, it will have no sense to keep the pad floating internally in the product ;) . It's managed by package in factory.

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@CBerg wrote:

In my Particular Case RUN_ENA (PC2_C) is an open drain GPIO. I should be able to use that pin in that configuration without have to care about the SYSCFG Register settings, as i am just using the default configuration.

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Indeed.