at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 249

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

SPI Chip Select Register
Name:
Access Type:
• CPOL: Clock Polarity
0 = The inactive state value of SPCK is logic level zero.
1 = The inactive state value of SPCK is logic level one.
CPOL is used to determine the inactive state value of the serial clock (SPCK). It is used with NCPHA to produce the
required clock/data relationship between master and slave devices.
• NCPHA: Clock Phase
0 = Data is changed on the leading edge of SPCK and captured on the following edge of SPCK.
1 = Data is captured on the leading edge of SPCK and changed on the following edge of SPCK.
NCPHA determines which edge of SPCK causes data to change and which edge causes data to be captured. NCPHA is
used with CPOL to produce the required clock/data relationship between master and slave devices.
• BITS: Bits Per Transfer
The BITS field determines the number of data bits transferred. Reserved values should not be used.
1790A–ATARM–11/03
31
23
15
7
SPI_CSR0... SPI_CSR3
Read/write
30
22
14
6
BITS[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
BITS
29
21
13
5
28
20
12
4
DLYBCT
DLYBS
SCBR
27
19
11
–
3
Bits Per Transfer
26
18
10
2
–
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
10
11
12
13
14
15
16
8
9
NCPHA
AT91RM3400
25
17
9
1
CPOL
24
16
8
0
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