UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 424 of 841
NXP Semiconductors
UM10360
Chapter 18: LPC176x/5x SSP0/1
18.6.3 SSPn Data Register (SSP0DR - 0x4008 8008, SSP1DR - 0x4003 0008)
Software can write data to be transmitted to this register, and read data that has been
received.
Table 371: SSPn Control Register 1 (SSP0CR1 - address 0x4008 8004, SSP1CR1 -
0x4003 0004) 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 372: SSPn Data Register (SSP0DR - address 0x4008 8008, SSP1DR - 0x4003 0008) 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
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