MIDIsense Hardware design notes
Supported Sensors

These are the sensors that are specifically supported

You can read more about the sensors and how to work with them on the sensor hardware page.

Board types

Instead of a general purpose board and then small interface circuits for each sensor (a lá Eobody or Miditron) there are 2 slightly specialized boards with differing firmware. This allows the boards to remain small, simple and inexpensive. It also means that its much easier to correctly wire up sensors 'out of the box.'

Here is a list board designs:

  1. Resistive sensor board. This design contains circuitry for handling resistive-type sensors. For example: bend sensors, pressure sensors, photosensors, etc.
  2. Analog & digital input. This design contains circuitry for handling pure 'analog' or 'digital' inputs such as from Sharp IR distance sensors, pushbuttons, tilt sensors, switches, potentiometers, etc.

Each board also contains the same power supply, microcontroller, MIDI in/out jacks, etc.

Power Supply

The power supply on each MIDIsense board is identical: one can use either a 9V battery or a 7.5V->12VDC, positive tip wall wart supply. There is also an on/off switch and an LED that lights up when the device is powered. The power supply converts the input voltage (7.5V to 12V) into 5V, which powers all of the electronics. Power supply draw/life is heavily dependant on what sensors are used. In general, a standard 300mA 9V battery should power the board (without sensors) for 15 hours.


The microcontroller used for the of the sensor boards is either a ATmega8 or the ATmega168, a low-medium scale device from Atmel. The microcontroller has a built-in UART (which is used for the MIDI interface), 6 x 10-bit analog to digital converters (A/D) and can be programmed in C.

The microcontroller runs at 8MHz or 16MHz (using an external oscillator) and can be reprogrammed using the standard 10-pin box header using any AVR "ISP" programmer.

MIDI interface

Each MIDIsense board has a standard MIDI in and MIDI out jack. The MIDI in jack is primarily used to configure the board, which is done with software. The MIDI out jack is where sensor data is sent.

May 17, 2011 20:07