Reading signal from UART2 port


I am trying to read a signal from UART2_RXD port in the A203V2 carrier board (which corresponds according to pinmux NVIDIA datasheet to GPIO3_PCC.06) but cannot seem to map it to a device in Linux4Tegra (dev/tty*).

Does anyone know if UART2_RXD is mapped to a specific device and how to read the signal from it?

Thanks in advance

Hi there Embedddev & welcome.
Can you give a little more information, ie. like a RS-232 data or a GPIO?
I like the Nvidia stuff, I have a rock64 with linux on it…
that carrier board looks nice. I have seen this:
The Jetson-IO tool currently supports pinmux setting for groups of pins related to a function, but not for the individual pins. or

GL :slight_smile: PJ

Hi @PJ_Glasso, first of all, thanks for your quick response.

In regards to your first link, I have already used Jetson.GPIO’s official NVIDIA library; and I am able to read specific pins, but the issue of mapping such signal to a specific device in the Linux tree persists. About the last link you sent, my use case is slightly different, because in the post they are trying to read UART1 signal, but my use case requires that I read from UART2 (which also seems to be a console debug port)

What I am trying to do is mapping a physical signal coming from GPIO3_PCC.06 (UART2_RXD) to a device in the Linux tree under the /dev directory. Using the gpiomon utility from the libgpiod library I am able to read the signal under gpiochip2 line 18 (which makes sense, because that specific line matches with GPIO3_PCC.06); so the signal seems that is being received by the carrier board.

The main issue is that I am unable to map that specific signal it to a specific device under the /dev directory (which is a requirement for my use case).

Thanks again for your time!

Hi there,
Maybe not relevant , but I saw somewhere you assign them in pairs UART? so maybe two pins need to be defined? Also that dev can be tricky command too
syntax matters,
What does the Device tree report:
GPIO_LOOKUP(chip_label, chip_hwnum, con_id, flags)
GPIO_LOOKUP_IDX(chip_label, chip_hwnum, con_id, idx, flags)

Im looking at this :GPIO Mappings — The Linux Kernel documentation
your’e close
GL :slight_smile: PJ

a good thread, Here

Hi @PJ_Glasso, yes UART is defined in pairs RX and TX.

The GPIO_LOOKUP and GPIO_LOOKUP_IDX commands look interesting. Let me take a look at it and report back.

Thanks for your time