Using USB port as serial UART

Question

So I have a circuit board (IWR6843ISK) that I want to connect to RPI400 via USB serial to send and receive data. Here are some details:

1. This board uses a USB to dual UART bridge (micro USB port).

2. I've tested this board connecting to both a windows 10 PC and a Linux VM on Mac (ubuntu 20.04). Both via USB-C and both works.

3. The RPI400 board is flashed with Ubuntu 20.04 (for ROS Noetic)

dmesg on my RPI is showing the following:

~$ dmesg | grep "tty"
[ 0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=0 bcm2708_fb.fbheight=0 bcm2708_fb.fbswap=1 smsc95xx.macaddr=E4:5F:01:07:54:98 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 elevator=deadline net.ifnames=0 console=ttyS0,115200 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait fixrtc quiet splash quiet splash
[ 0.000273] printk: console [tty1] enabled
[ 1.505079] fe201000.serial: ttyAMA0 at MMIO 0xfe201000 (irq = 14, base_baud = 0) is a PL011 rev2
[ 1.509591] printk: console [ttyS0] disabled
[ 1.509620] fe215040.serial: ttyS0 at MMIO 0x0 (irq = 16, base_baud = 62500000) is a 16550
[ 1.523278] printk: console [ttyS0] enabled
[ 6.537357] systemd[1]: Created slice system-serial\x2dgetty.slice.

I'm pretty sure neither ttyS0 nor ttyAMA0 is related to the USB/UART connection (1 is for the gpio UART pins and 1 is for Bluetooth).

Now my question is -- How can I get my rpi to send/receive serial data via the USB port? Or do I have to resort to using a microusb breakout board and connect the board to my rpi400 via gpio?

Answer 1

You have provided insufficient detail to answer "How can I get my rpi to send/receive serial data via the USB port?"

This depends on what data you want to use and what program.

First you need to identify the port/device. (It is definitely NOT ttyAMA0 or ttyS0.)

ls /sys/class/tty will show connected devices which should be accessible through /dev/tty??? e.g. /dev/ttyUSB0

usb-devices will show more detail of connected devices.