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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
397 of 808
NXP Semiconductors
UM10360
Chapter 18: LPC17xx SSP0/1 interface
6.2 SSPn Control Register 1 (SSP0CR1 - 0x4008 8004, SSP1CR1 -
0x4003 0004)
This register controls certain aspects of the operation of the SSP controller.
5:4
FRF
Frame Format.
00
00
SPI
01
TI
10
Microwire
11
This combination is not supported and should not be used.
6
CPOL
Clock Out Polarity. This bit is only used in SPI mode.
0
0
SSP controller maintains the bus clock low between frames.
1
SSP controller maintains the bus clock high between frames.
7
CPHA
Clock Out Phase. This bit is only used in SPI mode.
0
0
SSP controller captures serial data on the first clock transition
of the frame, that is, the transition
away from
the inter-frame
state of the clock line.
1
SSP controller captures serial data on the second clock
transition of the frame, that is, the transition
back to
the
inter-frame state of the clock line.
15:8
SCR
Serial Clock Rate. The number of prescaler-output clocks per
bit on the bus, minus one. Given that CPSDVSR is the
prescale divider, and the APB clock PCLK clocks the
prescaler, the bit frequency is PCLK / (CPSDVSR
×
[SCR+1]).
0x00
Table 350: SSPn Control Register 0 (SSP0CR0 - address 0x4008 8000, SSP1CR0 -
0x4003 0000) bit description
Bit
Symbol
Value
Description
Reset
Value
Table 351: 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.