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S3C2410A MEMORY CONTROLLER
5-17
REFRESH CONTROL REGISTER
Register Address R/W Description Reset Value
REFRESH 0x48000024 R/W SDRAM refresh control register 0xac0000
REFRESH Bit Description Initial State
REFEN [23] SDRAM Refresh Enable
0 = Disable 1 = Enable (self/auto refresh)
1
TREFMD [22] SDRAM Refresh Mode
0 = Auto Refresh 1 = Self Refresh
In self-refresh time, the SDRAM control signals are driven to the
appropriate level.
0
Trp [21:20] SDRAM RAS pre-charge Time
00 = 2 clocks 01 = 3 clocks 10 = 4 clocks 11 = Not support
10
Tsrc [19:18] SDRAM Semi Row Cycle Time
00 = 4 clocks 01 = 5 clocks 10 = 6 clocks 11 = 7 clocks
SDRAM's Row-Cycle time(Trc) = Tsrc + Trp
If) Trp=3 clocks & Tsrc=7 clocks, Trc = 3 + 7 = 10 clocks
11
Reserved [17:16] Not used 00
Reserved [15:11] Not used 0000
Refresh
Counter
[10:0] SDRAM refresh count value.
Refresh period = (2
11
-refresh_count+1)/HCLK
Ex) If refresh period is 15.6 us and HCLK is 60 MHz,
the refresh count is as follows:
Refresh count = 2
11
+ 1 - 60x15.6 = 1113
0