Interfaces

Sensors typically need to be interfaced to the computer in one way or another. It is possible to buy sensor interfaces, and it also possible to build them yourself. This page gives an overview of both.

• Basic sensor interfacing techniques
• Building a USB sensor interface
• Building a PIC USB sensor interface - external link
• Choosing an AVR microcontroller for data acquisition

Commercially available sensor interfaces intended for musical and artistic purposes generally use either MIDI or Open Sound Control (OSC) to communicate with a computer (see table below).

Popular MIDI devices (e.g. I-CubeX, MIDItron, Eo-body) have the advantage of being able to connect directly to any MIDI-compatible equipment. However, many interfaces need to be connected to a computer, at least temporarily, in order to configure them. Thus, if a MIDI interface is not part of the user's setup, it will need to be be added, boosting both the total price and potential problems of such a setup.

The shortcomings of MIDI in terms of resolution and speed, make OSC based sensor interfaces (e.g. Ethersense, Toaster, gluion) more attractive. Such devices typically allow for higher resolution and sampling rates, and long-distance communication over standard high-speed ethernet connections.

There are even devices that use digital audio for communication (e.g. Teabox), but this requires the computer to be equipped with a digital audio input.

Finally, a number of newer devices use serial ports for communication (via USB or Bluetooth), or straight USB/HID. While they still can easily be used for musical and artistic purposes given that the data can be re-routed to MIDI or OSC communication protocols, serial port and USB/HID communications are often used for physical computing applications.

Comparison of a number of popular sensor interfaces for musical and artistic purposes, ordered by their selling price.

Please note that prices and specifications are taken from the manufacturer’s websites or provided by manufacturers without independent verification, and have been generalized for the sake of comparison.

About the input sampling rate: while often the internal clock speed of A/D converters is expressed in MHz, the effective data acquisition rate is more commonly expressed in ksps (i.e. kilo samples per second). A/D conversion often requires a few clock cycles (depending on the wanted resolution), so that an A/D clock of 1 MHz doesn't mean that that interface is able to acquire data every 1/1,000,000 seconds. Though, many manufacturers express a supposedly real acquisition rate in Hz. Somewhat confusing!