UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1006 of 1269
NXP Semiconductors
UM10503
Chapter 39: LPC43xx SSP0/1
39.6.3 SSP Data Register
Software can write data to be transmitted to this register, and read data that has been
received.
Table 874: SSP Control Register 1 (CR1 - address 0x4008 3004 (SSP0), 0x400C 5004 (SSP1))
bit description
Bit
Symbol
Value Description
Reset
value
0
LBM
Loop Back Mode.
0
0
Normal operation.
1
Loop back mode. Serial input is taken from the serial output
(MOSI or MISO) rather than the serial input pin (MISO or MOSI
respectively).
1
SSE
SSP Enable.
0
0
The SSP controller is disabled.
1
The SSP controller will interact with other devices on the serial
bus. Software should write the appropriate control information to
the other SSP registers and interrupt controller registers, before
setting this bit.
2
MS
Master/Slave Mode.This bit can only be written when the SSE bit
is 0.
0
0
The SSP controller acts as a master on the bus, driving the
SCLK, MOSI, and SSEL lines and receiving the MISO line.
1
The SSP controller acts as a slave on the bus, driving MISO line
and receiving SCLK, MOSI, and SSEL lines.
3
SOD
Slave Output Disable. This bit is relevant only in slave mode
(MS = 1). If it is 1, this blocks this SSP controller from driving the
transmit data line (MISO).
0
31:4
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 875: SSP Data Register (DR - address 0x4008 3008 (SSP0), 0x400C 5008 (SSP1)) bit
description
Bit
Symbol
Description
Reset
value
15:0
DATA
Write:
software can write data to be sent in a future frame to this
register whenever the TNF bit in the Status register is 1, indicating that
the Tx FIFO is not full. If the Tx FIFO was previously empty and the
SSP controller is not busy on the bus, transmission of the data will
begin immediately. Otherwise the data written to this register will be
sent as soon as all previous data has been sent (and received). If the
data length is less than 16 bits, software must right-justify the data
written to this register.
Read:
software can read data from this register whenever the RNE bit
in the Status register is 1, indicating that the Rx FIFO is not empty.
When software reads this register, the SSP controller returns data from
the least recent frame in the Rx FIFO. If the data length is less than 16
bits, the data is right-justified in this field with higher order bits filled with
0s.
0x0000
31:16 -
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA