
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
193 of 487
NXP Semiconductors
UM10800
Chapter 13: LPC82x USART0/1/2
13.6.2 USART Control register
The CTL register controls aspects of USART operation that are more likely to change
during operation.
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 176. USART Configuration register (CFG, address 0x4006 4000 (USART0), 0x4006 8000
(USART1), 0x4006 C000 (USART2)) bit description
…continued …continued
Bit
Symbol
Value Description
Reset
Value