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UM10601
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© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
217 of 313
NXP Semiconductors
UM10601
Chapter 17: LPC800 SPI0/1
17.6.8 SPI Transmitter Data Register
The TXDAT register is written in order to send data via the SPI transmitter when control
information is not changing during the transfer (see
). That data will be sent
to the transmit shift register when it is available, and another character may then be
written to TXDAT.
17.6.9 SPI Transmitter Control register
The TXCTL register provides a way to separately access control information for the SPI.
These bits are another view of the same-named bits in the TXDATCTL register (see
). Changing bits in TXCTL has no effect unless data is later written to the
TXDAT register. Data written to TXDATCTL overwrites the TXCTL register.
When control information needs to be changed during transmission, the TXDATCTL
register should be used (see
) instead of TXDAT. Control information can
then be written along with data.
23
-
Reserved. Read value is undefined, only zero should be written.
NA
27:24 FLEN
Frame Length. Specifies the frame length from 1 to 16 bits. Note that frame lengths
greater than 16 bits are supported by implementing multiple sequential frames.
Note that if a 1-bit frame is selected, the master function will always insert a delay with
a length of one SCK time following the single clock seen on the SCK pin.
0x0 = Data frame is 1 bit in length.
0x1 = Data frame is 2 bits in length.
0x2 = Data frame is 3 bits in length.
...
0xF = Data frame is 16 bits in length.
0x0
31:28 -
Reserved. Read value is undefined, only zero should be written.
NA
Table 195. SPI Transmitter Data and Control register (TXDATCTL, addresses 0x4005 8018 (SPI0) , 0x4005 C018
(SPI1)) bit description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 196. SPI Transmitter Data Register (TXDAT, addresses 0x4005 801ST (SPI0) , 0x4005
C00C (SPI1)) bit description
Bit
Symbol
Description
Reset
value
15:0
DATA
Transmit Data. This field provides from 4 to 16 bits of data to be
transmitted.
0
31:16 -
Reserved. Only zero should be written.
NA