at75c220 ATMEL Corporation, at75c220 Datasheet - Page 29

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

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SDRAM_16bit Register
Register Name: SDRAM_16BIT
Access Type: Read/write
Reset Value: 0x1
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NR
NB
CAS
TWR
TRC
TRP
TRCD
TRAS
16BIT
Sets the number of row bits. Default is 11 row bits.
Sets the number of banks. Default is two banks.
Sets the CAS latency. The SDMC has been modified so that it only supports a CAS latency of two. Writing to this reg-
ister will have no effect.
Sets the value of TWR expressed in number of cycles. Default is two cycles.
Sets the value of TRC expressed in number of cycles. Default is eight cycles.
Sets the value of TRP expressed in number of cycles. Default is three cycles.
Sets the value of TRCD expressed in number of cycles. Default is three cycles.
Sets the value of TRAS expressed in number of cycles. Default is five cycles.
This bit is used to set the width of the external memory. If this field is set, the address is assumed to be 16 bits wide. If
not set, the memory bus is assumed to be 32 bits wide.
31
23
15
7
–
–
–
–
NR
NB
00
01
10
11
0
1
30
22
14
6
–
–
–
–
Number of Banks
29
21
13
5
–
–
–
–
Row Bits
Reserved
11
12
13
2
4
28
20
12
4
–
–
–
–
27
19
11
3
–
–
–
–
26
18
10
2
–
–
–
–
25
17
9
1
–
–
–
–
16BIT
24
16
8
0
–
–
–
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