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UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
267 of 464
NXP Semiconductors
UM10850
Chapter 21: LPC5410x USARTs (USART0/1/2/3)
21.6.2 USART Control register
The CTL register controls aspects of USART operation that are more likely to change
during operation.
Table 308. USART Control register (CTL, offset 0x04) bit description
Bit
Symbol
Value Description
Reset
Value
0
-
Reserved. Read value is undefined, only zero should be written.
NA
1
TXBRKEN
Break Enable.
0
0
Normal operation.
1
Continuous break. Continuous break is sent immediately when this bit is set, and
remains until this bit is cleared.
A break may be sent without danger of corrupting any currently transmitting
character if the transmitter is first disabled (TXDIS in CTL is set) and then waiting for
the transmitter to be disabled (TXDISINT in STAT = 1) before writing 1 to TXBRKEN.
2
ADDRDET
Enable address detect mode.
0
0
Disabled. The USART presents all incoming data.
1
Enabled. The USART receiver ignores incoming data that does not have the most
significant bit of the data (typically the 9th bit) = 1. When the data MSB bit = 1, the
receiver treats the incoming data normally, generating a received data interrupt.
Software can then check the data to see if this is an address that should be handled.
If it is, the ADDRDET bit is cleared by software and further incoming data is handled
normally.
5:3
-
Reserved. Read value is undefined, only zero should be written.
NA
6
TXDIS
Transmit Disable.
0
0
Not disabled. USART transmitter is not disabled.
1
Disabled. USART transmitter is disabled after any character currently being
transmitted is complete. This feature can be used to facilitate software flow control.
7
-
Reserved. Read value is undefined, only zero should be written.
NA
8
CC
Continuous Clock generation. By default, SCLK is only output while data is being
transmitted in synchronous mode.
0
0
Clock on character. In synchronous mode, SCLK cycles only when characters are
being sent on Un_TXD or to complete a character that is being received.
1
Continuous clock. SCLK runs continuously in synchronous mode, allowing
characters to be received on Un_RxD independently from transmission on Un_TXD).
9
CLRCCONRX
Clear Continuous Clock.
0
0
No effect. No effect on the CC bit.
1
Auto-clear. The CC bit is automatically cleared when a complete character has been
received. This bit is cleared at the same time.
15:10 -
Reserved. Read value is undefined, only zero should be written.
NA
16
AUTOBAUD
Autobaud enable.
0
0
Disabled. USART is in normal operating mode.
1
Enabled. USART is in autobaud mode. This bit should only be set when the USART
receiver is idle. The first start bit of RX is measured and used the update the BRG
register to match the received data rate. AUTOBAUD is cleared once this process is
complete, or if there is an AERR.
31:17 -
Reserved. Read value is undefined, only zero should be written.
NA