MPU-401 MIDI UART
Overview
Serial Port 3 is used exclusively in the LPC47B27x as an MPU-401-compatible MIDI Interface. The
LPC47B27x MPU-401 hardware includes a Host Interface, an MPU-401 command controller,
configuration registers, and a compatible UART (Figure 2).
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
UART
SA[15:0]
SD[7:0]
nIOW
nIOR
TX
RX
MIDI_OUT
MIDI_IN
HOST
INTERFACE
CONFIGURATION
REGISTERS
IRQ
FIGURE 2 - MPU-401 MIDI INTERFACE
NOTE: This figure is for illustration purposes only and is not intended to suggest specific
implementation details.
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 LPC47B27x 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 LPC47B27x
- 70 -
Rev. 08-10-04
DATASHEET
SMSC [ SMSC CORPORATION ]
