UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1005 of 1269
NXP Semiconductors
UM10503
Chapter 39: LPC43xx SSP0/1
39.6.2 SSP Control Register 1
This register controls certain aspects of the operation of the SSP controller.
Table 873: SSP Control Register 0 (CR0 - address 0x4008 3000 (SSP0), 0x400C 5000 (SSP1))
bit description
Bit
Symbol
Value Description
Reset
value
3:0
DSS
Data Size Select. This field controls the number of bits
transferred in each frame. Values 0000-0010 are not supported
and should not be used.
0000
0x3
4-bit transfer
0x4
5-bit transfer
0x5
6-bit transfer
0x6
7-bit transfer
0x7
8-bit transfer
0x8
9-bit transfer
0x9
10-bit transfer
0xA
11-bit transfer
0xB
12-bit transfer
0xC
13-bit transfer
0xD
14-bit transfer
0xE
15-bit transfer
0xF
16-bit transfer
5:4
FRF
Frame Format.
00
0x0
SPI
0x1
TI
0x2
Microwire
0x3
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
31:16 -
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA