The Bollion.fr module is a custom-built MIDI interface prototype designed to sound a programmable carillon for Tibetan bowls, gongs, and bells.
The operation is as follows:
The note(s) played from a keyboard with a MIDI output or from a connected MIDI sequencer (Cubase for example) are sent via MIDI cable to the Bollion module. To avoid any risk of feedback, the MIDI input of the Bollion module is equipped with an Optocoupler (E6N138) that transmits the signals to an Arduino Mega board. This board, using C++ software, processes and redirects the signals (notes and velocities) to control servomotors or solenoids.
This is done via a 16-channel PCA9685 Driver that controls the PWM pulses for the servomotors. The PCA9685 driver has its own power supply and can therefore control more powerful servos, for gongs for example. The PCA9685 driver is limited to 16 channels, but it is possible to connect 62 of them in series, which would allow for the control of a maximum of 992 servos (notes).
The interface is equipped with potentiometers that allow for precise adjustment of the servomotor travel or the sensitivity of the solenoids. Mallets of different lengths and weights can be mounted on these servos or solenoids to strike the bells, small bells, Tibetan bowls, or gongs.
The system is multitimbral and allows several notes to be played simultaneously, although with a slight latency due to the mechanical transmissions.
