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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
255 of 368
NXP Semiconductors
UM10375
Chapter 14: LPC13xx SSP0/1
14.7.3 SSP Data Register
Software can write data to be transmitted to this register, and read data that has been
received.
Table 244: SSP Control Register 1 (SSP0CR1 - address 0x4004 0004, SSP1CR1 - address
0x4005 8004) bit description
Bit
Symbol
Value
Description
Reset
value
0
LBM
Loop Back Mode.
0
0
During normal operation.
1
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 245: SSP Data Register (SSP0DR - address 0x4004 0008, SSP1DR - address
0x4005 8008) 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 bit, 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 bit, the data is right-justified in this
field with higher order bits filled with 0s.
0x0000
31:16 -
Reserved.
-