PC13 GPIO Usage recommendation on STM32G491MCT

Mahalakshmisudhakar · ‎2025-02-11

I am using the controller STM32G491MCT controller for my development project.I am running out of GPIO pins.I am planning to use PC13 to drive the level translator SN74LV4T125 for sending serial clock and data signals from my master device to the slave module. It is given in the datasheet that there is some limitations in the PC13,PC14 & PC15 pins which cannot be used for driving high speed signals.

Could you please confirm that can I use the PC13 for driving level translator?

Anticipating the earliest response!

Thanks in advance

Danish1 · ‎2025-02-12

For anyone to be able to answer that question correctly, we would need to know how you intend to use the pin PC13, and possibly the timing requirements for the "serial clock and data signals".

Will PC13 only drive the /OE pin on the level-translator? If so, would it be a problem if it were slow, perhaps taking a microsecond for the change to happen?

Or do you intend for PC13 to carry serial clock and/or data? (In which case there is a recommendation not to exceed 2 MHz; how does that compare to your intended bit-rate).

Andrew Neil · ‎2025-02-12

@Mahalakshmisudhakar wrote:
It is given in the datasheet that there is some limitations in the PC13,PC14 & PC15 pins which cannot be used for driving high speed signals

It gives you a lot more detail than that:

which is, surely, enough to answer the question?

@Mahalakshmisudhakar wrote:
Could you please confirm that can I use the PC13 for driving level translator?

Ask yourself:

Does this unnamed "level translator" require more than 3mA drive current ?
Does its load capacitance exceed 20pF ?
Does your signal exceed 2MHz ?

that should answer your question.

BTW: Note that the datasheet is incorrect in saying, "the switch only sinks (sic) a limited amount of current" - they mean sources.

See: https://community.st.com/t5/stm32-mcus-products/stm32f030-pc13-14-15-current-sink-limits/m-p/721081/highlight/true#M261048

@STTwo-32 - another datasheet needing correction.

Andrew Neil · ‎2025-02-12

@Andrew Neil wrote:
It gives you a lot more detail than that:

Here:

https://www.st.com/resource/en/datasheet/stm32g491mc.pdf#page=62