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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
398 of 808
NXP Semiconductors
UM10360
Chapter 18: LPC17xx SSP0/1 interface
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.
6.4 SSPn Status Register (SSP0SR - 0x4008 800C, SSP1SR -
0x4003 000C)
This read-only register reflects the current status of the SSP controller.
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
7:4
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
Table 351: SSPn Control Register 1 (SSP0CR1 - address 0x4008 8004, SSP1CR1 -
0x4003 0004) bit description
Bit
Symbol
Value
Description
Reset
Value
Table 352: 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
Table 353: SSPn Status Register (SSP0SR - address 0x4008 800C, SSP1SR - 0x4003 000C)
bit description
Bit
Symbol
Description
Reset Value
0
TFE
Transmit FIFO Empty. This bit is 1 is the Transmit FIFO is
empty, 0 if not.
1
1
TNF
Transmit FIFO Not Full. This bit is 0 if the Tx FIFO is full, 1 if not. 1
2
RNE
Receive FIFO Not Empty. This bit is 0 if the Receive FIFO is
empty, 1 if not.
0