LPC47M192 datasheet(79/228 Pages) SMSC

79 / 228 page

SMSC DS – LPC47M192

Page 79

Rev. 03/30/05

DATASHEET

7.7.2 HOST INTERFACE

Overview

The Host Interface includes two contiguous 8-bit run-time registers (the Status/Command Port and the Data Port),

and an interrupt. For illustration purposes, the Host Interface block shown in FIGURE 2 uses standard ISA signaling.

Address decoding and interrupt selection for the Host Interface are determined by device configuration registers (see

Section “MPU-401Configuration Registers”).

I/O Addresses

The Sound Blaster 16 MPU-401 UART mode MIDI interface requires two consecutive I/O addresses with possible

base I/O addresses of 300h and 330h. The default is 330h. The LPC47M192 MPU-401 I/O base address is

programmable on even-byte boundaries throughout the entire I/O address range (see Section “Activate and I/O Base

address”).

Registers (Ports)

The run-time registers in the MPU-401 Host Interface are shown below in Table 33.

Table 33 – MPU-401 HOST INTERFACE REGISTERS

ADDRESS

TYPE

DESCRIPTION

MIDI DATA

MPU-401 I/O Base Address

R/W

Used for MIDI transmit data, MIDI

receive data, and MPU-401 command

acknowledge.

STATUS

MPU-401 I/O Base Address + 1

Used to indicate the send/receive status

of the MIDI Data port.

COMMAND

MPU-401 I/O Base Address + 1

Used for MPU-401 Commands.

7.7.3 MIDI DATA PORT

The MIDI Data port exchanges MIDI transmit and MIDI receive data between the MPU-401 UART interface and the

host. The MIDI Data port is read/write (Table 34). The MIDI Data port is also used to return the command

acknowledge byte ‘FEh’ following host writes to the COMMAND port.

The MIDI Data port is full-duplex; i.e., the transmit and receive buffers can be used simultaneously.

An interrupt is generated when either MIDI receive data or a command acknowledge is available to the host in the

MIDI Data register. See Section “Bit 7 – MIDI Receive Buffer Empty” and “Interrupt”

Table 34 - MIDI Data Port

MPU-401 I/O BASE ADDRESS

DEFAULT

TYPE

R/W

n/a

NAME

MIDI DATA/COMMAND-ACKNOWLEDGE REGISTER

7.7.4 STATUS PORT

The Status port is used to indicate the state of the transmit and receive buffers in the MIDI Data port. The Status port

is read-only (Table 35). Status port Bit 6 is MIDI Transmit Busy, Bit 7 is MIDI Receive Buffer Empty. The remaining

bits in the Status port are RESERVED.

Table 35 - MPU-401 STATUS PORT

MPU-401 I/O BASE ADDRESS+1

DEFAULT

TYPE

0x80

BIT

NAME

MIDI RX

BUFFER

EMPTY

MIDI TX

BUSY

7.7.4.1

Bit 7 – MIDI Receive Buffer Empty

Bit 7 MIDI Receive Buffer Empty indicates the read state of the MIDI Data port (Table 36). If the MRBE bit is ‘0’, MIDI

Read/Command Acknowledge data is available to the host.

If the MRBE bit is ‘1’, MIDI Read/Command

Acknowledge data is NOT available to the host.

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