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10.0 Musical Instrument Digital Interface (MIDI) Port

10.1 OVERVIEW

This chapter describes a generic MIDI Port. For the implementation used in this device, see the

Device Architecture and

Conﬁguration chapter.

The MIDI Port is an asynchronous receiver/transmitter that uses a two-wire, bi-directional, relatively slow communication

channel to transmit and receive data bytes to or from MIDI-compliant devices, according to a predefined communication pro-

tocol. The MIDI Port is compatible with MPU-401 UART mode.

The MIDI was originally defined to establish a standard interface between computers and digital musical instruments such

as synthesizers, and has become the de facto standard for this purpose. However, the MIDI is also commonly used for other

purposes, such as communicating with advanced game devices.

The MIDI Port serves as a communication pipe between software and a MIDI device. The software and the MIDI device must

interpret the data they exchange, and act accordingly.

The MIDI Port supports the following two feature types:

Legacy (MPU-401)

Enhanced.

Legacy. These include all features supported by MPU-401 UART mode. They can all be operated via the Legacy I/O ad-

dress space of 2 bytes, traditionally allocated for the MIDI Port.

Enhanced. These features extend the capabilities of the MIDI Port. They can only be operated if the MIDI is allocated with

an address space of at least 3 bytes.

The basic system configuration of the MIDI Port consists of the port itself, a single pull-up resistor for the MDRX pin, and a

MIDI compliant device. This system configuration is shown in Figure 31. The purpose of the pull-up resistor is to make sure

that the MIDI Port senses an inactive (high) MIDI receive signal in the absence of a MIDI device.

Figure 31. MIDI System Conﬁguration

10.2 FUNCTIONAL DESCRIPTION

The MIDI Port consists of five major functional blocks:

Internal Bus Interface Unit

Port Control and Status Registers

Data Buffers and FIFOs

MIDI Communication Engine

MIDI Signals Routing Control Logic.

See Figure 32 for a block diagram of the MIDI Port.

MIDI

Port

MIDI Transmit

MIDI Receive

Game

Device

MIDI

Device

MIDI Receive

MIDI Transmit

MDRX Pin

MDTX Pin

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