TouchDRO Project

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TouchDRO is a BlueTooth wireless DRO project aimed at creating an easy to build and flexible, yet powerful Digital Readout system that uses Android tablet as the main display and one of the inexpensive DRO scale controllers for scale interface. It offers all of the traditional DRO functions, such as metric/inch system support, absolute and incremental coordinate systems, hole circle and pattern functions, tool library with tool offsets, point memory, etc. On top of that, by using multi-touch capabilities and processing power of a modern android tablet, TouchDRO can offer much more ergonomic user interface and functionality, not available from the standard DRO units.
The application is available absolutely free on Google Play store, and a scale controller can be build or purchased for as little as $30*.

TIP: If you're contemplating putting together a DIY DRO but don't know where to start, take a look at the "Android DRO Step By Step Overview". It should give you an idea of what you're getting yourself into.

TouchDRO Android Application

TouchDRO is a free Android application designed to provide the features of a commercial DRO unit with much more intuitive abd responsive user interface. In conjunction with one of the inexpensive BlueTooth scale interface controllers, TouchDRO can read vast majority of the DRO scales available on the market. The list of supported scales ranges from inexpensive Chinese calipers to 1 micron glass and magnetic DRO scales.


  • USB and Bluetooth connectivity support
  • Display for up to three* linear axes, rotary axis and a tachometer
  • Support for metric an imperial units (mm and inch)
  • Support for standard DRO functions:
    • Tool Offset
    • Preset Dimension
    • “1/2” Function
    • Hole Circle (Arch)
    • Arbitrary Hole Circle (Arch)
    • Hole Grid
  • Unlimited** point memory
  • Multiple workspaces
  • Graphical layout view with point auto-selection
*A fourth linear axis can be combined with one of the primary axes on milling machines with separate quill and knee/head scales.
** Actually, it’s theoretically limited by the size of internal tablet storage, but even a cheap tablet can store billions of points.

System Requirements

  • Android OS 4.0 or newer
  • 7" multi-touch screen with 800x480 resolution*
  • BlueTooth or USB support
* Altough the application will work on a 4", or even smaller, screen, a tablet with at least 7” 1024x600 screen is highly recommended.

Recommended Tablets

  • Google Nexus 7 (2013 Model)
  • Google Nexus 7 (2012 Model)
  • Samsung Galaxy Tab 2 (7-Inch, Wi-Fi)
  • Samsung Galaxy Tab 4 (7-Inch, Wi-Fi)
  • The tablets above range in price between $160 and $250, but many inexpensive tablets would work just as well for the DRO display. When choosing an inexpensive tabled please ensure that it comes with Anrdoid 4.0 OS. Many off-brand tablets advertised as running Android 4.0 use an older version that is heavily “skinned” to look like 4.0. The only sure way to know if the device is running Android 4.x is to check the Kernel version, which should be 3.0.1 or newer. If the Kernel version is older, the application will not install and/or properly.

    Do-it-Yourself DRO Scale Controllers

    DIY controllers provide similar functionality to the pre-made boards, and with exception of the iGaging version, use the same firmware.

      MSP430 LaunchPad iGaging DRO Controller More Information

      This controller uses a Texas Instruments MSP430 Value Line Launchpad kit with MSP430G2553 microcontroller to interface with up to four iGaging DigiMag/AccuRemote/Shahe DRO scales.

      MSP430 LaunchPad Mixed Scale DRO Controller More Information

      This DRO controller extends upon the basic version of MSP430 Launchpad-based controller by adding support for standard "chinese" scales and inexpensive calipers.

      MSP430 LaunchPad Quadrature DRO Controller More Information

      Quadrature controller is 100% pin-compatible with the Mixed Scale version, but uses firmware optimized for quadrature encoders, including 1 micron magnetic and glass DRO scales.

      Arduino Basic DRO Controller More Information

      Uses the ubiquitous Arduino to read the scales and transmit the position to the Android app via Bluetooth-to-Serial adapter or USB cable. The main advantage of this design is the availability of the parts. With the exception of the Bluetooth transceiver all of the required components are available [in the USA] at the Radio Shack and many other electronic stores.

    Controller Firmware Comparison

    Please note, firmware listed below is free for personal (non-commercial) use. For commercial use or re-sale you can either purchase a pre-made board or contact me for a licensing arrangement.

      Arduino MSP430 LaunchPad
    Basic iGaging Mixed Scale Quadrature
    Supported Scales/Protocols
    21 bit
    i.e. AccuRemote & iGaging
    Yes Yes Yes No
    A.K.A. 24 BIT Chinese Scales
    No No Yes No
    A.K.A. "Cheap Calipers"
    No No Yes No
    Quadrature Encoders
    i.e. Glass & Magnetic Scales
    No No No Yes
    General Information
    Number of Axes 4 4 4 4
    Tachometer Support Yes (directional) Yes (directional) Yes (directional) Yes (directional)
    Scale Read Frequency 24 Hz 10 Hz Up to 100 Hz Continuous
    Position Update Frequency 24 Hz 10 Hz 10 Hz 10 Hz
    Tachometer Update Frequency 2 Hz 1 Hz 1 Hz 1 Hz