Blog Home

OpenMoco strikes again: the DollyShield

Davide GombaJuly 23rd, 2010

Some time ago I headed in one of the most complete DIY photo/cinema solutions for low-budget productions, the OpenMoco. It seems they spent some time in prototyping a brand new shield:

The DollyShield is an adaptation of the Arduino Motor Shield v3 that provides directional PWM control of two DC motors, at up to 1A of current each.  In addition to the motor drivers, it also provides a stereo plug with dual opto-coupled outputs for direct camera control, a 2×16 LCD, five user input buttons, and four auxilliary inputs or outputs through two stereo jacks.  It is designed to provide an inexpensive and easy-to-use interface for two-axis motion control integrated with a camera.

more info after the break

Since I’m video making myself,  I find very interesting every low-budget inhancement of my production. The DollyShield is a way to help videomakers and photographers find their way among a wide range of DIY solutions, that often need a coding knowledge. Here’s come the DollyShield: easy to use, assembled (or at least easy-to-assemble), powerful tool for various needs.

The design is based on the Arduino Motor Shield, and uses the same L293B driver chip and driver circuitry.  It expands on the normal capabilities of the motor shield by providing all elements necessary for a stand-alone user interface, an integrated and isolated camera connection, easy access to the hardware serial pins through a stereo jack, and an additional stereo jack connecting to pins 2 and 3 of the Arduino to allow for the use of encoders or limit switches.  Pins 2 and 3 are chosen for their association with hardware interrupts which increase the reliability of encoder or limit switch actions. Using the DollyShield, one may quickly and easily experiment with 2-axis motion control systems designed around DC motors, and even utilize encoders for servo-like precision.

On the DollyShield, there are three 1/8″ stereo jacks.  One provides a connection for the camera focus and shutter remote pins, isolated from the circuit with optocouplers, one provides direct connection to the hardware serial pins, and the third provides direction connection to digital pins 2 and 3.  There are two DC barrel jacks on the right-hand side of the board, providing connections for each motor.  These barrel jacks use a 2.5×5.5mm pin config to prevent accidentally hooking up DC power to the motor outputs.  (The arduino DC input is 2.1×5.5mm.)  An additional LED displays when the camera is currently exposing.

General Design Philosophy

  • Two-sided design for compactness
  • Two-layer for low-cost production
  • All under-side parts out of the way of Arduino components (except USB connector – need tape)
  • No heatsinks required if using 2oz copper pour (entire bottom is heat sink)
  • All through-hole components for easy assembly by beginners
  • No bare pads for hook-ups, ready for field use with TRS connectors and DC barrel jacks


  • Arduino “shield” (requires Arduino board)
  • 2x DC Motor Speed/Direction PWM Drivers (Up to 1A)
  • 1x 1/8″ TRS Plug for isolated camera connection (focus+shutter)
    • 1x Camera exposing LED
  • 2x 1/8″ TRS Plug for auxiliary I/O (Hardware Serial, Digital 2+3)
    • Can be used for encoders, limit switches, serial communication other boards, etc.
  • 1x 16×2 LCD for display
  • 5x Momentary pushbuttons
  • 2x DC Barrel Jacks for Motor Hookup
  • 9v-12v supply voltage
  • Compact: 3.85×2.7″
  • Low-cost

good work.
I wonder how much is going to cost and when it is going to be distributed.

more on [OpenMoco]