This MIDI board design can be directly plugged into the arduino use. Supports MIDI communication protocol, you can control synthesizers and other music equipment. MIDI standard asynchronous serial interface protocol and have a lot of similarities, you can use the arduino controller UART port to send and receive MIDI data.
MIDI board provides MIDI-IN and MIDI-OUT port, and MIDI-THRU port. When MIDI board when directly plugged into the arduino, MIDI-IN / THRU connection is arduino hardware serial RX pin, MIDI-OUT is connected TX. MIDI-IN port is optically isolated, to prevent ground loops. Dial-board switch to download MIDI arduino code without removing the board, will dial switch to OFF (ie disconnect the arduino RX) when you download the code, after downloading the hit ON.
MIDI devices are generally divided into two categories: the controller (which produce equipment MIDI signals) and synthesizers (including sampling, sequencing, etc.). After the latter got into MIDI data to make noise or light or other effects.
MIDI is a serial protocol, it can be transmitted per second 31250. Arduino's built-in serial ports can be sent at this rate.
MIDI byte is divided into two types: command byte and data bytes. The command byte is generally 128 or more, or hexadecimal form of 0x80 ~ 0xFF. Digital bytes generally less than 127,0x00 ~ 0x7F.