UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
293 of 515
NXP Semiconductors
UM11029
Chapter 17: LPC84x USART0/1/2/3/4
18
OETA
Output Enable Turnaround time enable for RS-485
operation.
0
0
De-asserted. If selected by OESEL, the Output Enable
signal de-asserted at the end of the last stop bit of a
transmission.
1
Asserted. If selected by OESEL, the Output Enable signal
remains asserted for 1 character time after then end the last
stop bit of a transmission. OE will also remain asserted if
another transmit begins before it is de-asserted.
19
AUTOADDR
Automatic Address matching enable.
0
0
Disabled. When addressing is enabled by ADDRDET,
address matching is done by software. This provides the
possibility of versatile addressing (e.g. respond to more than
one address).
1
Enabled. When addressing is enabled by ADDRDET,
address matching is done by hardware, using the value in
the ADDR register as the address to match.
20
OESEL
Output Enable Select.
0
0
Flow control. The RTS signal is used as the standard flow
control function.
1
Output enable. The RTS signal is taken over in order to
provide an output enable signal to control an RS-485
transceiver.
21
OEPOL
Output Enable Polarity.
0
0
Low. If selected by OESEL, the output enable is active low.
1
High. If selected by OESEL, the output enable is active high.
22
RXPOL
Receive data polarity.
0
0
Not changed. The RX signal is used as it arrives from the
pin. This means that the RX rest value is 1, start bit is 0, data
is not inverted, and the stop bit is 1.
1
Inverted. The RX signal is inverted before being used by the
UART. This means that the RX rest value is 0, start bit is 1,
data is inverted, and the stop bit is 0.
23
TXPOL
Transmit data polarity.
0
0
Not changed. The TX signal is sent out without change. This
means that the TX rest value is 1, start bit is 0, data is not
inverted, and the stop bit is 1.
1
Inverted. The TX signal is inverted by the UART before
being sent out. This means that the TX rest value is 0, start
bit is 1, data is inverted, and the stop bit is 0.
31:24 -
Reserved. Read value is undefined, only zero should be
written.
NA
Table 323. USART Configuration register (CFG, address 0x4006 4000 (USART0), 0x4006 8000
(USART1), 0x4006 C000 (USART2), 0x4007 0000 (USART3), 0x4007 4000
(USART4)) bit description
…continued
Bit
Symbol
Value Description
Reset
Value