LPC47M192 datasheet(78/228 Pages) SMSC

78 / 228 page

SMSC DS – LPC47M192

Page 78

Rev. 03/30/05

DATASHEET

This pin will remain low following a VCC POR until the TXD2 function is selected for the pin AND serial

port 2 is enabled by setting the activate bit, at which time the pin will reflect the state of the transmit

output of serial port 2. Following a VCC POR, setting the TXD2_MODE bit (bit 5 in Serial Port 2 Mode

from low to tristate, regardless of the function selected on the pin (GPIO of TXD2), regardless of the

state of the activate bit for serial port 2 and regardless of the state of VCC. When VCC is removed from

the part while the TXD2_MODE bit is set to ‘1’, the TXD2 pin will remain tristate unless a VTR POR

occurs, which will reset the TXD2_MODE bit.

This pin will remain low following a VCC POR until the corresponding GPIO data bit (GP5 register bit 3)

is set or the polarity bit in the GP53 control register is set.

When Serial Port 2 is subsequently deactivated, the TXD2/IRTX pin will be driven low.

The TXD2_MODE bit is implemented for modems that do not assert the ring indicator pin when TXD2 is sensed low.

If required, this bit should be used as follows:

When the activate bit for serial port 2 is cleared prior to entering a sleep state, set the TXD2_MODE bit.

When the activate bit for serial port 2 is set, upon exiting a sleep state clear the TXD2_MODE bit.

The IRTX2 pin is not affected by the TXD2_MODE bit.

7.7 MPU-401 MIDI UART

7.7.1 OVERVIEW

Serial Port 3 is used exclusively in the LPC47M192 as an MPU-401-compatible MIDI Interface. The LPC47M192

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).

HOST

INTERFACE

IRQ

SA[15:0]

SD[7:0]

UART

MIDI_IN

MIDI_OUT

MPU-401

COMMAND

CONTROLLER

nIOR

nIOW

CONFIGURATION

REGISTERS

FIGURE 2 - MPU-401 MIDI INTERFACE

Note: This figure is for illustration purposes only and is not intended to suggest specific implementation details.

LPC47M192 Datasheet(PDF) 78 Page - SMSC Corporation

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