The N-Trig multitouch device

As of Q1 2009, N-Trig's DuoSense is the touch input device on three computers: HP's TouchSmart tx2 and Dell's XT and XT2. This makes multitouch available at a very reasonable price, but there is still some confusion on the availability of multitouch. Apparently, this depends not only on the operating system but also on the firmware that is installed in the device.


What multitouch?

The DuoSense is a dual device: it detects both the stylus and the fingers. The finger detection system is able to detect multiple fingers. But at the date of writing and as far as we know:
  • these two features have not been observed to work at the same time: either you have single touch + stylus, or you have multitouch alone. This results both from observation and from analysis of the HID report descriptors. The HID report descriptors we have either leave room for multiple fingers *or* contain fields for the stylus.
  • finger tracking is not performed in the firmware. It is done by the software driver on Windows 7.

    Of course, if someone has more accurate information, we'll be happy to include it here.

    Firmware versions

    We have asked a few people to give us the firmware version on their N-Trig DuoSense along with the observed behaviour and, when available, the HID report descriptors obtained on a Linux machine with 'lsusb -v'.

    Observed by On Win Firmware Win driver Software bundle Behaviour Default descriptors Analysis
    Rafi Rubin xt 3.2.11.3.5 1.23 Pen, no multitouch not available
    Olivier Thauvin xt2 3.5.5.13.5 1.26 1.88 Pen, some multitouch link no multitouch in reports
    Stephane Chatty tx2 7000 3.5.8.8.5 1.26 8.18 pen, no multitouch link no multitouch in reports
    Pascal Giard tx2 Vista 3.5.9.8.5 1.26 1.89 Pen, some multitouch link
    Stephane Chatty tx2 7000 4.2.17.8.5 1.26 8.18 no pen, multitouch link multitouch visible in reports
    Rafi Rubin xt 7100 4.3.6.3.5 1.26 2.59 Pen/multitouch Evidence of mode switching
    Stephane Chatty tx2 7100 4.3.6.8.5 1.26 2.59 Pen/multitouch link Evidence of mode switching
    Thomas Hansen 4.3.6.13.5 1.26 2.59.0
    Stephane Chatty tx2 7000 4.5.31.8.5 2.184 both pen and multitouch, 3 modes


    Contact: chatty at enac.fr
    Updated Mar 31, 2010