Kionix Inc., Ithaca, NY, offers the KXTF9 triaxial accelerometer with a directional tap/double tap algorithm in its ASIC. This allows you to create up to 12 tap-enabled commands for customer-specified functions. The functionality detects a quick, light tap or double tap on any of the six faces of any object. The algorithm then lets the accelerometer discern a single or double tap and the direction from which the tap originated. Other features include an I2C interface, user-programmable output data rate, ADC at user-defined sampling rates, 8- or 12-bit selectable resolution, user-selectable 2 g, 4 g, or 8 g ranges, and a digital high-pass filter with a user-selectable cut-off frequency.
Triaxial Accelerometer from Kionix