
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
195 of 487
NXP Semiconductors
UM10800
Chapter 13: LPC82x USART0/1/2
13.6.3 USART Status register
The STAT register primarily provides a complete set of USART status flags for software to
read. Flags other than read-only flags may be cleared by writing ones to corresponding
bits of STAT. Interrupt status flags that are read-only and cannot be cleared by software,
can be masked using the INTENCLR register (see
).
The error flags for received noise, parity error, framing error, and overrun are set
immediately upon detection and remain set until cleared by software action in STAT.
16
AUTOBAUD
Autobaud enable.
0
0
Disabled. UART is in normal operating mode.
1
Enabled. UART is in autobaud mode. This bit should only
be set when the UART is enabled in the CFG register and
the UART 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 ABERR. This bit can
be cleared by software when set, but only when the UART
receiver is idle. Disabling the UART in the CFG register
also clears the AUTOBAUD bit.
31:17 -
Reserved. Read value is undefined, only zero should be
written.
NA
Table 177. USART Control register (CTL, address 0x4006 4004 (USART0), 0x4006 8004
(USART1), 0x4006 C004 (USART2)) bit description
Bit
Symbol
Value
Description
Reset
value
Table 178. USART Status register (STAT, address 0x4006 4008 (USART0), 0x4006 8008 (USART1), 0x4006 C008
(USART2)) bit description
Bit
Symbol
Description
Reset
value
Access
0
RXRDY
Receiver Ready flag. When 1, indicates that data is available to be read from
the receiver buffer. Cleared after a read of the RXDAT or RXDATSTAT
registers.
0
RO
1
RXIDLE
Receiver Idle. When 0, indicates that the receiver is currently in the process of
receiving data. When 1, indicates that the receiver is not currently in the
process of receiving data.
1
RO
2
TXRDY
Transmitter Ready flag. When 1, this bit indicates that data may be written to
the transmit buffer. Previous data may still be in the process of being
transmitted. Cleared when data is written to TXDAT. Set when the data is
moved from the transmit buffer to the transmit shift register.
1
RO
3
TXIDLE
Transmitter Idle. When 0, indicates that the transmitter is currently in the
process of sending data.When 1, indicate that the transmitter is not currently
in the process of sending data.
1
RO
4
CTS
This bit reflects the current state of the CTS signal, regardless of the setting of
the CTSEN bit in the CFG register. This will be the value of the CTS input pin
unless loopback mode is enabled.
NA
RO
5
DELTACTS
This bit is set when a change in the state is detected for the CTS flag above.
This bit is cleared by software.
0
W1