UM10850
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User manual
Rev. 2.4 — 13 September 2016
353 of 464
NXP Semiconductors
UM10850
Chapter 24: LPC5410x System FIFO for Serial Peripherals
24.5.21 Transmit data register for SPIn
The TXDATCTLSPI register allows writing data to the transmit FIFO that will later be
written by the System FIFO to the SPI TXDAT register. Each SPI has a dedicated
TXDATCTLSPI register.
TXDATCTLSPI can be written as a halfword or as a word, which in practice corresponds
to the writing to the SPI TXDAT, TXCTL, and TXDATCTL registers as follows:
•
A word write to TXDATCTLSPI contains both data and control information for the SPI.
•
A halfword write to the lower half of TXDATCTLSPI contains only data for the SPI.
•
A halfword write to the upper half of TXDATCTLSPI contains only control information
for the SPI.
Control information is saved within the FIFO and appended to all data writes to the SPI.
Table 409. Received data register for SPIn (RXDATSPI[0:1], address offset [0x2014:0x2114]) bit description
Bit
Symbol
Description
Reset
Value
15:0
RXDAT
Receiver Data. This contains the next piece of received data. The number of bits that
are used depends on the LEN setting in TXCTL / TXDATCTL.
NA
16
RXSSEL0_N
Slave Select for receive. This field allows the state of the SSEL0 pin to be saved along
with received data. The value will reflect the SSEL0 pin for both master and slave
operation. A zero indicates that a slave select is active. The actual polarity of each slave
select pin is configured by the related SPOL bit in CFG.
NA
17
RXSSEL1_N
Slave Select for receive. This field allows the state of the SSEL1 pin to be saved along
with received data. The value will reflect the SSEL1 pin for both master and slave
operation. A zero indicates that a slave select is active. The actual polarity of each slave
select pin is configured by the related SPOL bit in CFG.
NA
18
RXSSEL2_N
Slave Select for receive. This field allows the state of the SSEL2 pin to be saved along
with received data. The value will reflect the SSEL2 pin for both master and slave
operation. A zero indicates that a slave select is active. The actual polarity of each slave
select pin is configured by the related SPOL bit in CFG.
NA
19
RXSSEL3_N
Slave Select for receive. This field allows the state of the SSEL3 pin to be saved along
with received data. The value will reflect the SSEL3 pin for both master and slave
operation. A zero indicates that a slave select is active. The actual polarity of each slave
select pin is configured by the related SPOL bit in CFG.
NA
20
SOT
Start of Transfer flag. This flag will be 1 if this is the first data after the SSELs went from
deasserted to asserted (i.e., any previous transfer has ended). This information can be
used to identify the first piece of data in cases where the transfer length is greater than
16 bit.
NA
31:21 -
Reserved, the value read from a reserved bit is not defined.
NA
Table 410. Address map TXDATCTLSPI[0:1] registers
Peripheral
Base address
Offset
Increment
Dimension
VFIFO
0x1C03 8000
[0x2018:0x2118]
0x100
2