PC87373 datasheet(133/174 Pages) NSC

133 / 174 page

11.0 Musical Instrument Digital Interface (MIDI) Port (Continued)

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Revision 1.1

When in UART mode, the MIDI Port responds to commands given by the host as follows:

A command of FFh returns the MIDI Port to Pass-Thru mode, and resets it to its initial state.

All other commands, issued while the MIDI Port is in UART mode, are ignored.

When switching from UART mode to Pass-Thru mode, any data previously stored in the Receive FIFO is lost, unless the

FIFO is enabled for Pass-Thru mode.

As in Pass-Thru mode, if a command is issued to the MIDI Port while the MIDI Communication Engine is in the middle of a

byte transfer, the execution of the command and the response are postponed until the current byte transfer is completed.

The MIDI commands supported by the MIDI Port and their respective responses are listed in Table 49.

After each MIDI Port operation in UART mode, the MSTAT register is updated accordingly.

Table 49. MIDI Commands Supported by the MIDI Port

11.2.7 MIDI Port Status Flags

The status of the various functional units of the MIDI Port is reflected by the MSTAT register. This register is functional in

both Pass-Thru and UART modes. Some of the status indications provided by the MSTAT register are not included in the

Legacy definition of the MIDI Port. These indications can be ignored if they are not required by the software.

The following status flags are included in the Legacy definition of the MIDI Port:

Receive Buffer Empty

Transmit Buffer Full

The Receive Buffer Empty flag is reflected by bit 7 of the MSTAT register. The Transmit Buffer Full flag is reflected by bit 6

of the MSTAT register. When operating in UART mode, these bits reflect the status of the Receive and Transmit FIFOs.

The Receive Buffer Empty status flag is cleared to 0 also when an acknowledge byte is put by the MIDI Port itself following

a MIDI command.

The values of these bits are set by the MIDI Port hardware and are not affected by reading the MSTAT register.

The following status indications are provided by the MIDI Port, although they are not included in the Legacy definition of the

MIDI Port:

Receive FIFO Full

Transmit FIFO Empty

Receive Overrun Error

MIDI Port Operation Mode

Command

MIDI Port Response

Pass-Thru Mode

UART Mode

3Fh

Enter UART mode

FEh (Acknowledge)

Ignored

A0h-A7h, ABh

FEh (Acknowledge)

00h

Ignored

ACh

FEh (Acknowledge)

15h

Ignored

ADh

FEh (Acknowledge)

01h

Ignored

AFh

FEh (Acknowledge)

64h

Ignored

FFh

MIDI Port Reset

FEh (Acknowledge)

Enter Pass-Thru Mode

MIDI Port Reset

Others

FEh (Acknowledge)

Ignored

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