453
11054A–ATARM–27-Jul-11
SAM9X25
453
11054A–ATARM–27-Jul-11
SAM9X25
30.7.2
DDRSDRC Refresh Timer Register
Name:
DDRSDRC_RTR
Address:
0xFFFFE804
Access:
Read-write
Reset:
This register can only be written if the bit WPEN is cleared in
“DDRSDRC Write Protect Mode Register” on page 466
• COUNT: DDRSDRC Refresh Timer Count
This 12-bit field is loaded into a timer which generates the refresh pulse. Each time the refresh pulse is generated, a refresh
sequence is initiated.
SDRAM devices require a refresh of all rows every 64 ms. The value to be loaded depends on the DDRSDRC clock fre-
quency (MCK: Master Clock) and the number of rows in the device.
For example, for an SDRAM with 8192 rows and a 100 MHz Master clock, the value of Refresh Timer Count bit is pro-
grammed: (((64 x 10
-3
)/8192) x100 x10
6
= 781 or 0x030D.
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
COUNT
7
6
5
4
3
2
1
0
COUNT
Summary of Contents for SAM9X25
Page 26: ...26 11054A ATARM 27 Jul 11 SAM9X25...
Page 138: ...138 11054A ATARM 27 Jul 11 SAM9X25 138 11054A ATARM 27 Jul 11 SAM9X25...
Page 162: ...162 11054A ATARM 27 Jul 11 SAM9X25 162 11054A ATARM 27 Jul 11 SAM9X25...
Page 216: ...216 11054A ATARM 27 Jul 11 SAM9X25 216 11054A ATARM 27 Jul 11 SAM9X25...
Page 266: ...266 11054A ATARM 27 Jul 11 SAM9X25 266 11054A ATARM 27 Jul 11 SAM9X25...
Page 330: ...330 11054A ATARM 27 Jul 11 SAM9X25 330 11054A ATARM 27 Jul 11 SAM9X25...
Page 374: ...374 11054A ATARM 27 Jul 11 SAM9X25...
Page 468: ...468 11054A ATARM 27 Jul 11 SAM9X25 468 11054A ATARM 27 Jul 11 SAM9X25...
Page 532: ...532 11054A ATARM 27 Jul 11 SAM9X25 532 11054A ATARM 27 Jul 11 SAM9X25...
Page 692: ...692 11054A ATARM 27 Jul 11 SAM9X25 692 11054A ATARM 27 Jul 11 SAM9X25...
Page 777: ...777 11054A ATARM 27 Jul 11 SAM9X25 777 11054A ATARM 27 Jul 11 SAM9X25...
Page 886: ...886 11054A ATARM 27 Jul 11 SAM9X25 886 11054A ATARM 27 Jul 11 SAM9X25...
Page 962: ...962 11054A ATARM 27 Jul 11 SAM9X25 962 11054A ATARM 27 Jul 11 SAM9X25...
Page 1036: ...1036 11054A ATARM 27 Jul 11 SAM9X25 1036 11054A ATARM 27 Jul 11 SAM9X25...
Page 1128: ...1128 11054A ATARM 27 Jul 11 SAM9X25 1128 11054A ATARM 27 Jul 11 SAM9X25...
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