Wacom Tablet, serial protocols - Page 1
Forum section: electronics / general

author: legacy
author_rank: Super Contributor
timestamp: January 09, 2019, 02:17:54 pm
content: so, for weird reasons, we got a dozen(1) "UD-06-08-R" and "UD-12-12_R" tablets made by Wacom in the 90s. They are a legacy product and use a very old serial protocol rather than a USB-something.The Wacom tablets popularity pre-dates the popularity of USB ports and were connected using serial ports.On DTB, we want to develop an embedded application with super cheap tablets, but we have difficulties at finding the documentation about the protocol.Wacom's doc is ... a mess and it seems the old archive is gone. Besides they seem more focused on modern USB tablets with poor support for Linux, so I have to give a look to the Wacom-Linux-project, which is completely independent, but yet again I can't find the documentation for the serial tablets.Anyone?basically, we want to get- x,y- pressure 0..99%edit:(1) some were not working, not good for parts, some are damaged but fixable or good for parts, and three tablets of twelve got repaired

author: legacy
author_rank: Super Contributor
timestamp: January 09, 2019, 04:28:30 pm
content: so, I think, I am kooking for Wacom III, IV, V protocols

author: metrologist
author_rank: Super Contributor
timestamp: January 09, 2019, 04:34:54 pm
content: I thought it would look like a typical HID, like the old mice/keyboards used serial IO.

author: coppice
author_rank: Super Contributor
timestamp: January 09, 2019, 04:39:11 pm
content: Most Wacom tablets work OK with Linux. When I was helping with the Wacom driver for Linux many years ago, I think the old serial protocols were all handled in the driver code I started with. Wacom were quite helpful at that time. Its nearly 20 years ago, so I might be misremembering, but its worth a look in the source code.

author: legacy
author_rank: Super Contributor
timestamp: January 09, 2019, 04:43:59 pm
content: this? (wacom_serial-120327-1.tar.bz2)

author: legacy
author_rank: Super Contributor
timestamp: January 09, 2019, 04:46:52 pm
content: Quote from: metrologist on January 09, 2019, 04:34:54 pmWhen a Wacom serial tablet is connected to a serial port, software can interact with it directly by opening the appropriate device, usually /dev/ttyS0. The Wacom X driver does precisely this, and all stylus movements are converted into X input events for programs like the Gimp to turn into fluid brush strokes.Wacom tablets are capable of handling a number of different data protocols, and the Linux Wacom Project code currently utilitizes two,Wacom Protocol IV and Protocol V(our UD-08-08 seems using Protocol IV ... not sure). Each operates with a fixed-sized packet, the length of which depends on the model and ROM version.When the serial tablet is reset, it defaults to a standard baud rate, often 38400 baud (our UD-08-08 works at 9600). From there, the device type can be queried, and if the tablet supports it, the baud rate increased to a higher value. Additionally, model parameters like tablet size can be queried directly to determine which features are available.Once configured, the tablet streams data back to the application as tools are brought into and out of proximity, are pressed against the tablet surface, or are tilted or inverted.

author: helius
author_rank: Super Contributor
timestamp: January 09, 2019, 05:21:26 pm
content: I believe this is what you're looking for

author: legacy
author_rank: Super Contributor
timestamp: January 09, 2019, 06:13:48 pm
content: Quote from: helius on January 09, 2019, 05:21:26 pmThanks! It's exactly what I was looking for