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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
216 of 313
NXP Semiconductors
UM10601
Chapter 17: LPC800 SPI0/1
17.6.7 SPI Transmitter Data and Control register
The TXDATCTL register provides a location where both transmit data and control
information can be written simultaneously. This allows detailed control of the SPI without a
separate write of control information for each piece of data.
When control information remains static during transmit, the TXDAT register should be
used (see
) instead of the TXDATCTL register. Control information can then
be written separately via the TXCTL register (see
). The upper part of
TXDATCTL (bits 27 to 16) are the same bits contained in the TXCTL register. The two
registers simply provide two ways to access them.
For details on the slave select process, see
.
For details on using multiple consecutive frames for frame lengths larger than 16 bit, see
Section 17.7.5 “Data lengths greater than 16 bits”
Table 195. SPI Transmitter Data and Control register (TXDATCTL, addresses 0x4005 8018 (SPI0) , 0x4005 C018
(SPI1)) bit description
Bit
Symbol
Value
Description
Reset
value
15:0
TXDAT
Transmit Data. This field provides from 1 to 16 bits of data to be transmitted.
0
16
TXSSELN
Transmit Slave Select . This field controls what is output for SSEL in master mode.
Remark:
The active state of the SSEL function is configured by bits in the CFG
register.
0
0
SSEL asserted.
1
SSEL not asserted.
19:17 -
Reserved.
20
EOT
End of Transfer. The asserted SSEL will be deasserted at the end of a transfer, and
remain so for at least the time specified by the Transfer_delay value in the DLY
register.
0
0
SSEL not deasserted. This piece of data is not treated as the end of a transfer. SSEL
will not be deasserted at the end of this data.
1
SSEL deasserted. This piece of data is treated as the end of a transfer. SSEL will be
deasserted at the end of this piece of data.
21
EOF
End of Frame. Between frames, a delay may be inserted, as defined by the
Frame_delay value in the DLY register. The end of a frame may not be particularly
meaningful if the FRAME_DELAY value = 0. This control can be used as part of the
support for frame lengths greater than 16 bits.
0
0
Data not EOF. This piece of data transmitted is not treated as the end of a frame.
1
Data EOF. This piece of data is treated as the end of a frame, causing the
FRAME_DELAY time to be inserted before subsequent data is transmitted.
22
RXIGNORE
Receive Ignore. This allows data to be transmitted using the SPI without the need to
read unneeded data from the receiver to simplify the transmit process.
0
0
Read received data. Received data must be read in order to allow transmission to
progress. In slave mode, an overrun error will occur if received data is not read before
new data is received.
1
Ignore received data. Received data is ignored, allowing transmission without reading
unneeded received data. No receiver flags are generated.