Enable additional UART on VIM4

VIM4
1

Which system do you use? Android, Ubuntu, OOWOW or others?

Ubuntu 22.04

Which version of system do you use? Khadas official images, self built images, or others?

Khadas Official image

Please describe your issue below:

Hello,

I was wondering if it is possible to enable a 2nd UART besides uart_e (Pin15 / 16) on the Khadas VIM4. I saw for the KHADAS VIM3 it seems possible to enable UART on Pin 22/23, but I have looked into the dtb overlay and tried modifying the dtb.img and could enable additional UARTS, but looking at the schematics none of those seem to be connected to any of the GPIO headers.

Is there a way to use e.g. Pin 22/23 as an additional UART?

2

You can’t use Pin 22/23 as an additional UART, but you can use Pin 18/19 as an additional UART, but you will can’t use the debug console, does it ok for you?

@Electr1 please followup to enable Pin 18/19 as a normal UART if the user need it.

3

Hello @stuffen

you can download and install this package on your VIM4, if you would like to use the linux uart pin 18/19

wget https://github.com/sravansenthiln1/images/releases/download/v0.5/linux-u-boot-vim4-vendor_1.5.2-2019.01_arm64.deb
sudo dpkg -i linux-u-boot-vim4-vendor_1.5.2-2019.01_arm64.deb
sync
reboot

After installing, note that /dev/ttyS0 will be the device node for that UART pins, there will be some boot logs from the uart pins from the bootloader, after completing the boot, you can use it normally as general UART device.

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4

Yes, we saw another post on how to disable the linux debug uart and use pin 18/19 as a “normal UART”, and it seems to be fine for our application. We will try to move forward with these pins.

For other users, in case the link from electr1 won’t work in the future: You can build the uboot-deb yourself, and need to modify one file to disable UART linux console, as explained here: How to configure the debugging serial port as a general serial port for use?.

Thanks for the quick reply.

1 Like