UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
963 of 1269
NXP Semiconductors
UM10503
Chapter 37: LPC43xx USART0_2_3
The PulseDiv bits in U3ICR are used to select the pulse width when the fixed pulse width
mode is used in IrDA mode (IrDAEn = 1 and FixPulseEn = 1). The value of these bits
should be set so that the resulting pulse width is at least 1.63 µs.
shows the
possible pulse widths.
37.6.12 USART Fractional Divider Register
The USART Fractional Divider Register (FDR) controls the clock pre-scaler for the baud
rate generation and can be read and written at the user’s discretion. This pre-scaler takes
the APB clock and generates an output clock according to the specified fractional
requirements.
Important:
If the fractional divider is active (DIVADDVAL > 0) and DLM = 0, the value of
the DLL register must be 3 or greater.
1
IRDAINV
Serial input direction.
0
0
The serial input is not inverted.
1
The serial input is inverted. This has no effect on the
serial output.
2
FIXPULSEEN
IrDA fixed pulse width mode.
0
0
IrDA fixed pulse width mode disabled.
1
IrDA fixed pulse width mode enabled.
5:3
PULSEDIV
Configures the pulse when FixPulseEn = 1. See
for details.
0
31:6
-
NA
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
0
Table 835. IrDA Pulse Width
FixPulseEn
PulseDiv
IrDA Transmitter Pulse width (µs)
0
x
3 / (16
baud rate)
1
0
2
T
PCLK
1
1
4
T
PCLK
1
2
8
T
PCLK
1
3
16
T
PCLK
1
4
32
T
PCLK
1
5
64
T
PCLK
1
6
128
T
PCLK
1
7
256
T
PCLK
Table 834. IrDA Control Register (ICR - address 0x4000 8024) bit description
Bit
Symbol
Value Description
Reset
value