little-scale: Multiplexing MIDI Output Streams with Arduino. Sebastian writes –
Arduino can easily generate MIDI output data for use with external synths and modules or to take physical events and turn them into control data for use with software synths and applications etc.
Although the Arduino only has one Serial output, it is still possible to use a multiplexer to send multiple streams of MIDI data to multiple devices.
The idea is pretty simple. The Arduino still uses its TX pin for sending serial data, but uses an analog multiplexer to choose where that data is going (say, one of two MIDI outputs for example). The analog multiplexer that I have chosen is a 4051 and can ‘route’ the data to up to eight different places.