No ttyACM0 with Pro Micro on Ubuntu 18.04

Question

I am trying to determine the dev path of a USB keyboard running an Arduino Pro Micro on my Ubuntu 18.04 system. The files /dev/ttyACM0 and /dev/ttyUSB0 do not exist.

When I run dmesg I get:

[  410.770931] usb 3-3: new full-speed USB device number 3 using xhci_hcd
[  410.962180] usb 3-3: New USB device found, idVendor=feed, idProduct=3060, bcdDevice= 0.01
[  410.962184] usb 3-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  410.962187] usb 3-3: Product: Dactyl-Manuform (5x6)
[  410.962189] usb 3-3: Manufacturer: tshort
[  410.962191] usb 3-3: SerialNumber: 0
[  411.006440] input: tshort Dactyl-Manuform (5x6) as /devices/pci0000:00/0000:00:07.1/0000:11:00.3/usb3/3-3/3-3:1.0/0003:FEED:3060.0008/input/input27
[  411.063192] hid-generic 0003:FEED:3060.0008: input,hidraw0: USB HID v1.11 Keyboard [tshort Dactyl-Manuform (5x6)] on usb-0000:11:00.3-3/input0
[  411.089097] input: tshort Dactyl-Manuform (5x6) Mouse as /devices/pci0000:00/0000:00:07.1/0000:11:00.3/usb3/3-3/3-3:1.1/0003:FEED:3060.0009/input/input28
[  411.147172] input: tshort Dactyl-Manuform (5x6) System Control as /devices/pci0000:00/0000:00:07.1/0000:11:00.3/usb3/3-3/3-3:1.1/0003:FEED:3060.0009/input/input29
[  411.147297] input: tshort Dactyl-Manuform (5x6) Consumer Control as /devices/pci0000:00/0000:00:07.1/0000:11:00.3/usb3/3-3/3-3:1.1/0003:FEED:3060.0009/input/input30
[  411.147395] hid-generic 0003:FEED:3060.0009: input,hidraw1: USB HID v1.11 Mouse [tshort Dactyl-Manuform (5x6)] on usb-0000:11:00.3-3/input1

Dactyl-Manuform is the keyboard so it seems to recognize the device. The command lsusb returns several usb devices. The entry with no title is the keyboard (based on doing watch lsusb):

Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 003: ID feed:3060  
Bus 003 Device 002: ID 045e:02d1 Microsoft Corp. XBOX One Controller for Windows
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 1e7d:2c2e ROCCAT 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

I have installed arduino and arduino-core from the official repos.

However, I still cannot get a ttyACM0 or ttyUSB0 to appear, and in the Arduino IDE the "Serial Port" option is greyed out (even when using sudo).

What can I check for to either 1) get the ttyACM0 file to exist for my Arduino device or 2) find some other dev port to use as the serial port?

Answer 1

A Pro Micro will only give a /dev/ttyACMx device node if the firmware installed on it creates a CDC/ACM interface. That device obviously is running custom firmware which only provides the interfaces that the manufacturer wants to provide - in this case keyboard and mouse interfaces.

To use it as an Arduino you will first have to install the Arduino bootloader. That will then remove the existing manufacturer firmware, and you will have to write your own to make it act as a keyboard again.