at75c220 ATMEL Corporation, at75c220 Datasheet - Page 138

• Manufacturer Part Number: at75c220
• Description: Smart Internet Appliance Processor Siap
• Manufacturer: ATMEL Corporation

SPI Chip Select Register
Register Name:SP_CSR0
Access Type:Read/write
Reset Value:0x0
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138
BITS[3:0]
CPOL: Clock Polarity
NCPHA: Clock Phase
BITS: Bits Per Transfer
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 a
desired clock/data relationship between master and slave devices.
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 a desired clock/data relationship between master and slave devices.
The BITS field determines the number of data bits transferred. Reserved values should not be used.
0000
0001
0010
0011
0100
0101
0110
0111
31
23
15
7
Transfer
Bits per
10
11
12
13
14
15
8
9
30
22
14
6
AT75C220
BITS
BITS[3:0]
1000
1001
1010
1011
1100
1101
1110
1111
29
21
13
5
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Transfer
Bits per
16
28
20
12
4
DLYBCT
DLYBS
SCBR
27
19
11
3
–
26
18
10
2
–
NCPHA
25
17
9
1
CPOL
24
16
8
0