6.8 MPU-401 MIDI UART
6.8.1
Overview
Serial Port 3 is used exclusively in the LPC47M14x as an MPU-401-compatible MIDI Interface. The LPC47M14x
MPU-401 hardware includes a Host Interface, an MPU-401 command controller, configuration registers, and a
compatible UART (FIGURE 3).
Each of these components are discussed in detail, below.
Only the MPU-401 UART (pass-through) mode is included in this implementation. MPU-401 UART mode is
supported on the Sound Blaster 16 Series-compatible MIDI hardware. The Sound Blaster 16 hardware is supported
by Microsoft Windows Operating Systems.
In MPU-401 UART mode, data is transferred without modification between the host and the MIDI device (UART).
Once UART mode is entered using the UART MODE command (3Fh), the only MPU-401 command that the interface
recognizes is RESET (FFh).
MPU-401
COMMAND
CONTROLLER
SA[15:0]
SD[7:0]
nIOW
nIOR
UART
TX
RX
MIDI_OUT
MIDI_IN
HOST
INTERFACE
CONFIGURATION
REGISTERS
IRQ
FIGURE 3 – MPU-401 MIDI INTERFACE
Note: This figure is for illustration purposes only and is not intended to suggest specific implementation
details.
6.8.2
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 3 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 LPC47M14x 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”).
SMSC DS – LPC47M14X
Page 73
Rev. 03/19/2001
SMSC [ SMSC CORPORATION ]
