The modern smartphone or tablet (mobile device) has more computing power than desktop computers had just 10 years ago. Modern mobile devices are full of sensors including: GPS, compass, 3-axis accelerometers, gyroscopes, etc and are well connected via cellular network, WiFi, and Bluetooth. Chances are, you have an old iphone or Android phone in a drawer somewhere collecting dust. Put it to good use in STEMbot1 and help teach a kid to program.
Programming is an important part of many Science, Technology, Engineering, and Math (STEM) education programs. Breaking a large task into smaller tasks is at the core of programming, and easily demonstrated graphically by visual based programming languages like Catroid. Mobile devices with high resolution touch screen displays make visual programming a literal “hand-on experience”. Inserting the mobile device into a DIY project that moves according to the program written using the GUI provides direct visual and physical feedback of the programming effort.
STEMbot1 is a simple two-wheel robot using two RC servos as drive motors. The RC servos plug into an A2SCB_ML servo controller from EMGRobotics. The A2SCB_ML plugs into the headphone jack of the Android phone running Catroid, RFO BASIC, EMGRobotics Robot Controller, or the EMGRobotics RC Servo Controller. STEMbot1 can be built in less than an hour and requires no soldering.
STEMbot1 is easy to build, requiring only eight components. The build process is described with lots of pictures in the STEMbot1 Instructable. A video explaining how to program STEMbot1 using Catroid is available on YouTube. A blog covering Catroid on STEMbot1 is available here. Look for additional information about programming STEMbot1 using RFO BASIC on the EMGRobotics website.
STEMbot1 is possible due to the cost and capabilities of the TI MSP430G2231. The MSP430 interfaces to the phone via the headphone jack. The smartphone creates tone sequences which are decoded by a DSP algorithm running in the MSP430. The MSP430 decodes multiple tones, runs a state machine, and generats two RC servo PWM signals, all for less than $0.75.
If you would like to build your own STEMbot1, check out the Instructable, or purchase the kit on Kickstarter.