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UM10237_2
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 02 — 19 December 2008
546 of 792
NXP Semiconductors
UM10237
Chapter 20: LPC24XX SSP interface SSP0/1
6.2 SSPn Control Register 1 (SSP0CR1 - 0xE006 8004, SSP1CR1 -
0xE003 0004)
This register controls certain aspects of the operation of the SSP controller.
Table 471: SSPn Control Register 0 (SSP0CR0 - address 0xE006 8000, SSP1CR0 -
0xE003 0000) 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
0011
4 bit transfer
0100
5 bit transfer
0101
6 bit transfer
0110
7 bit transfer
0111
8 bit transfer
1000
9 bit transfer
1001
10 bit transfer
1010
11 bit transfer
1011
12 bit transfer
1100
13 bit transfer
1101
14 bit transfer
1110
15 bit transfer
1111
16 bit transfer
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