Arduino Sketch

dropControllerBT&PC Arduino Sketch version
No longer need to select the communication method. Just upload and run. Requires Windows app or later. Download from below. Previous versions of the app will no longer work with this sketch.

Sketch version 9 and above requires the Android app version 1-37 or above. Update through Google play

Arduino Sketch History

Version 14
– removed the Number Of Valves option. Number of valves is now always set to 6.
– simplified the communication protocol between the dropController and the Windows app.
– fixed some problems caused when flash trigger is set to 0
Version 10b
– No longer required to select the device type (USB or Bluetooth) and the option in the sketch has been removed.
– removed the version count on start
– the waiting LED now blinks until a connection is made
– made the debug mode user viewable. Added a button on the settings page.
Version 009d
– minor bug fix
Version 009c
– minor bug fixes
Version 009
– dropControllerBT and dropControllerPC now use the same sketch
– set the device you are using in the sketch before compiling. Default is dropControllerBT.
Version 006.
– Moved the pins around
Version 005.
– Added valve drain function
Version 004
– Added FOCUS trigger in makeDrops function
– Changed the shutter close time for bulb mode. The shutter now closes 100ms after the flash fires.
Version 003.
– Shortened the acknowledgement code.


The Arduino sketch requires the digitalIOPerformance library. This is actually outdated but still works with all 328 based Arduinos. I have tried in Arduino IDE 1.6.3 and 1.8.3 and the sketch compiles fine. I use IDE 1.6.3 for all development. The library does not work with newer non AVR Arduinos.


Android App

The dropController app can be downloaded from Google play.
The current app has a slight bug feature. On start up, if the number of valves is set to 1 the SOL list will still activate but the list will be empty. Just hit the back button.

Android App History

Version 1-37
– added 3 more valves
– the dropController device can now be used with a Windows PC with Bluetooth.
– requires sketch version 009 or above.
Version 1-35
– minor bug fixes
– added the About page
Version 1-32
– tidied up the graphics
Version 1-27
– First release


App Inventor aia file

The dropController Bluetooth app was created is App Inventor 2. You can download version 38 of the aia file here.


Windows Program

DropController Windows app. Version

The Windows program does not need to be installed and is run directly from a folder. It requires the .net framework, minimum version 4.0, available at Microsoft .net 4.0 download page and will run on Windows XP SP2 and above.

– change the versioning number format
– added debug mode
– minor bug fixes

– Bug fix: number of valves. Now able to select 1-6


Windows Program Source Files

The Windows app was written in Visual Basic 2013 using the Visual Studio 2013 Community IDE.
It has been updated in Visual Basic 2017 using the Visual Studio 2017 Community IDE

DropController Windows app. Version source files

Visual Studio 2017 Community is free to use for students, open source contributors and small development teams and it is available for download at The download is just the installer which will download the main program from the internet. An offline installer is not available for Visual Studio 2017 Community.

An offline installer of Visual Studio 2013 from


Original Version

The original version used a keypad and LCD and was far more complex and inconvenient to use. For those interested see dropController Original version. The page includes a download link for the Arduino sketch. The sketch is heavily commented so you should be able to follow what it does.
This version is no longer supported and I may not be able to answer questions about it.