Avian’s Blog

Wacom Cintiq 16 (DTK-1660/K0-BX) is a drawing tablet that was announced late last year. At around 600€ I believe it's now the cheapest tablet with a display you can buy from Wacom. For a while I've been curious about these things, but the professional Wacoms were just way too expensive and I wasn't convinced by the cheaper Chinese alternatives. I've been using a small Intuos tablet for several years now and Linux support has been flawless from the start. So when I recently saw the Cintiq 16 on sale at a local reseller and heard there are chances that it will work similarly well on Linux I couldn't resist buying one.

Even though it's a very recent device, the Linux kernel already includes a compatible driver. Regardless, I was prepared for some hacking before it was usable on Debian. I was surprised how little was actually required. As before, the Linux Wacom Project is doing an amazing job, even though Linux support is not officially acknowledged by Wacom as far as I know.

The tablet connects to the computer using two cables: HDMI and USB. HDMI connection behaves just like a normal 1920x1080 60 Hz flat panel monitor and the display works even if support for everything else is missing on the computer side. The HDMI cable also caries an I²C connection that can be used to adjust settings that you would otherwise expect in a menu accessible by buttons on the side of a monitor (aside from a power button, the Cintiq itself doesn't have any buttons).

After loading the i2c-dev kernel module, the ddcutil version 0.9.4 correctly recognized the display. The i2c-2 bus interface in the example below goes through the HDMI cable and was in my case provided by the radeon driver:

$ ddcutil detect
Display 1
   I2C bus:             /dev/i2c-2
   EDID synopsis:
      Mfg id:           WAC
      Model:            Cintiq 16
      Serial number:    ...
      Manufacture year: 2018
      EDID version:     1.3
   VCP version:         2.2
$ ddcutil --bus=2 capabilities
MCCS version: 2.2
Commands:
   Command: 01 (VCP Request)
   Command: 02 (VCP Response)
   Command: 03 (VCP Set)
   Command: 06 (Timing Reply )
   Command: 07 (Timing Request)
   Command: e3 (Capabilities Reply)
   Command: f3 (Capabilities Request)
VCP Features:
   Feature: 02 (New control value)
   Feature: 04 (Restore factory defaults)
   Feature: 05 (Restore factory brightness/contrast defaults)
   Feature: 08 (Restore color defaults)
   Feature: 12 (Contrast)
   Feature: 13 (Backlight control)
   Feature: 14 (Select color preset)
      Values:
         04: 5000 K
         05: 6500 K
         08: 9300 K
         0b: User 1
   Feature: 16 (Video gain: Red)
   Feature: 18 (Video gain: Green)
   Feature: 1A (Video gain: Blue)
   Feature: AC (Horizontal frequency)
   Feature: AE (Vertical frequency)
   Feature: B2 (Flat panel sub-pixel layout)
   Feature: B6 (Display technology type)
   Feature: C8 (Display controller type)
   Feature: C9 (Display firmware level)
   Feature: CC (OSD Language)
      Values:
         01: Chinese (traditional, Hantai)
         02: English
         03: French
         04: German
         05: Italian
         06: Japanese
         07: Korean
         08: Portuguese (Portugal)
         09: Russian
         0a: Spanish
         0d: Chinese (simplified / Kantai)
         14: Dutch
         1e: Polish
         26: Unrecognized value
   Feature: D6 (Power mode)
      Values:
         01: DPM: On,  DPMS: Off
         04: DPM: Off, DPMS: Off
   Feature: DF (VCP Version)
   Feature: E1 (manufacturer specific feature)
      Values: 00 01 02 (interpretation unavailable)
   Feature: E2 (manufacturer specific feature)
      Values: 01 02 (interpretation unavailable)
   Feature: EF (manufacturer specific feature)
      Values: 00 01 02 03 (interpretation unavailable)
   Feature: F2 (manufacturer specific feature)

I didn't play much with these settings, since I found the factory setup sufficient. I did try out setting white balance and contrast and the display responded as expected. For example, to set the white balance to 6500K:

$ ddcutil --bus=2 setvcp 14 5

Behind the USB connection is a hub and two devices connected to it:

$ lsusb -s 1:
Bus 001 Device 017: ID 0403:6014 Future Technology Devices International, Ltd FT232H Single HS USB-UART/FIFO IC
Bus 001 Device 019: ID 056a:0390 Wacom Co., Ltd 
Bus 001 Device 016: ID 056a:0395 Wacom Co., Ltd 
$ dmesg
...
usb 1-6: new high-speed USB device number 20 using ehci-pci
usb 1-6: New USB device found, idVendor=056a, idProduct=0395, bcdDevice= 1.00
usb 1-6: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-6: Product: Cintiq 16 HUB
usb 1-6: Manufacturer: Wacom Co., Ltd.
hub 1-6:1.0: USB hub found
hub 1-6:1.0: 2 ports detected
usb 1-6.2: new high-speed USB device number 21 using ehci-pci
usb 1-6.2: New USB device found, idVendor=0403, idProduct=6014, bcdDevice= 9.00
usb 1-6.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-6.2: Product: Single RS232-HS
usb 1-6.2: Manufacturer: FTDI
ftdi_sio 1-6.2:1.0: FTDI USB Serial Device converter detected
usb 1-6.2: Detected FT232H
usb 1-6.2: FTDI USB Serial Device converter now attached to ttyUSB0
usb 1-6.1: new full-speed USB device number 22 using ehci-pci
usb 1-6.1: New USB device found, idVendor=056a, idProduct=0390, bcdDevice= 1.01
usb 1-6.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-6.1: Product: Cintiq 16
usb 1-6.1: Manufacturer: Wacom Co.,Ltd.
usb 1-6.1: SerialNumber: ...
input: Wacom Cintiq 16 Pen as /devices/pci0000:00/0000:00:1a.7/usb1/1-6/1-6.1/1-6.1:1.0/0003:056A:0390.000D/input/input62
on usb-0000:00:1a.7-6.1/input0

056a:0395 is the hub and 056a:0390 is the Human Interface Device class device that provides the actual pen input. When the tablet is off but connected to power, the HID disconnects but other two USB devices are still present on the bus. I'm not sure what the UART is for. This thread on GitHub suggests that it offers an alternative way of interfacing with the I²C bus for adjusting the display settings.

On the stock 4.9.130 kernel that comes with Stretch the pen input wasn't working. However, the 4.19.12 kernel from stretch-backports correctly recognizes the devices and as far as I can see works perfectly.

$ cat /proc/version
Linux version 4.19.0-0.bpo.1-amd64 (debian-kernel@lists.debian.org) (gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1)) #1 SMP Debian 4.19.12-1~bpo9+1 (2018-12-30)

I'm using the stock GNOME 3.22 desktop that comes with Stretch. After upgrading the kernel, the tablet correctly showed up in the Wacom Tablet panel in gnome-control-center. Pen settings there also work and I was able to calibrate the input using the Calibrate button. Calibration procedure instructs you to press the pen onto targets shown on the display and looks exactly like when using official software on Mac OS.

Update: It seems that GNOME sometimes messes up the tablet-to-screen mapping. If the stylus suddenly starts to move the cursor on some other monitor instead of displaying it underneath the stylus on the Wacom display, check the key /org/gnome/desktop/peripherals/tablets/056a:0390/display in dconf-editor. It should contain something like ['WAC', 'Cintiq 16', '...']. If it doesn't, delete they key and restart gnome-settings-daemon.

In GIMP I had to enable the new input devices under Edit, Input Devices and set them to Screen mode, same as with other tablets. You get two devices: one for the pen tip and another one for when you turn the pen around and use the other eraser-like end. These two behave like independent devices in GIMP, so each remembers its own tool settings.

As far as I can see, pen pressure, tilt angle and the two buttons work correctly in GIMP. The only problem I had is that it's impossible to do a right-click on the canvas to open a menu. This was already unreliable on the Intuos and I suspect it has to do with the fact that the pen always moves slightly when you press the button (so GIMP registers click-and-drag rather than a click). With the higher resolution of the Cintiq it makes sense that it's even harder to hold the pen still enough.

Otherwise, GIMP works mostly fine. I found GNOME to be a bit stubborn about where it wants to place new dialog windows. If I have a normal monitor connected alongside the tablet, file and color chooser dialogs often end up on the monitor instead of the tablet. Since I can't use the pen to click on something on the monitor, it forces me to reach for the mouse, which can be annoying.

I've noticed that GIMP sometimes lags behind the pen, especially when dragging the canvas with the middle-click. I didn't notice this before, but I suspect it has to do with the higher pen resolution or update rate of the Cintiq. The display also has a higher resolution than my monitor, so there are more pixels to push around. In any case, my i5-750 desktop computer will soon be 10 years old and is way overdue for an upgrade.

In conclusion, I'm very happy with it even if it was a quite an expensive gadget to buy for an afternoon hobby. After a few weeks I'm still getting used to drawing onto the screen and tweaking tool dynamics in GIMP. The range of pressures the pen registers feels much wider than on the Intuos, although that is probably very subjective. To my untrained eyes the display looks just amazing. The screen is actually bigger than I thought and since it's not easily disconnectable it is forcing me to rethink how to organize my desk. In the end however, my only worry is that my drawing skills are often not on par with owning such a powerful tool.