The HACMAD is a project consisting of a handheld base unit and interchangeable sensor dongles. All of the code for each sensor is pre-loaded in the main sketch. Each dongle has resistors that the base unit uses to determine which portion of the main sketch to run. Build Log is located here: http://hackaday.io/project/836/log/1995 Available files: Main Case Dongle Shell, Basic-Top (used for whatever) Dongle Shell, Basic-Bottom (used for whatever) Dongle Shell, Tachometer-Top (use with Basic-bottom) Version 0.1 has the following capabilities: Temp / Humidity Sensor Tachometer Ultrasonic Distance Measurement RC Servo Tester Project Status: Adding code and dongles will be continuous. If you would like to contribute or suggest ideas, please do so!