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UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
273 of 464
NXP Semiconductors
UM10850
Chapter 21: LPC5410x USARTs (USART0/1/2/3)
21.6.10 USART Interrupt Status register
The read-only INTSTAT register provides a view of those interrupt flags that are currently
enabled. This can simplify software handling of interrupts. See
for detailed
descriptions of the interrupt flags.
21.6.11 Oversample selection register
The OSR register allows selection of oversampling in asynchronous modes. The
oversample value is the number of BRG clocks used to receive one data bit. The default is
industry standard 16x oversampling.
Changing the oversampling can sometimes allow better matching of baud rates in cases
where the peripheral clock rate is not a multiple of 16 times the expected maximum baud
rate. For all modes where the OSR setting is used, the USART receiver takes three
consecutive samples of input data in the approximate middle of the bit time. Smaller
values of OSR can make the sampling position within a data bit less accurate and may
potentially cause more noise errors or incorrect data.
Table 316. USART Interrupt Status register (INTSTAT, offset 0x24) bit description
Bit
Symbol
Description
Reset Value
0
RXRDY
Receiver Ready flag.
0
1
-
Reserved. Read value is undefined, only zero should be written.
NA
2
TXRDY
Transmitter Ready flag.
1
3
TXIDLE
Transmitter Idle status.
0
4
-
Reserved. Read value is undefined, only zero should be written.
NA
5
DELTACTS
This bit is set when a change in the state of the CTS input is detected.
0
6
TXDISINT
Transmitter Disabled Interrupt flag.
0
7
-
Reserved. Read value is undefined, only zero should be written.
NA
8
OVERRUNINT
Overrun Error interrupt flag.
0
10:9
-
Reserved. Read value is undefined, only zero should be written.
NA
11
DELTARXBRK
This bit is set when a change in the state of receiver break detection occurs.
0
12
START
This bit is set when a start is detected on the receiver input.
0
13
FRAMERRINT
Framing Error interrupt flag.
0
14
PARITYERRINT
Parity Error interrupt flag.
0
15
RXNOISEINT
Received Noise interrupt flag.
0
16
ABERRINT
Auto baud Error Interrupt flag.
0
31:17
-
Reserved. Read value is undefined, only zero should be written.
NA
Table 317. Oversample selection register (OSR, offset 0x28) bit description
Bit
Symbol
Description
Reset value
3:0
OSRVAL
Oversample Selection Value.
0 to 3 = not supported
0x4 = 5 peripheral clocks are used to transmit and receive each data bit.
0x5 = 6 peripheral clocks are used to transmit and receive each data bit.
...
0xF= 16 peripheral clocks are used to transmit and receive each data bit.
0xF
31:4
-
Reserved, the value read from a reserved bit is not defined.
NA