350
8331B–AVR–03/12
Atmel AVR XMEGA AU
27.10.6
SDRAMCTRLC – SDRAM Control register C
• Bit 7:6 – WRDLY[1:0]: SDRAM Write Recovery Delay
These bits select the write recovery time in number of Clk
PER2
cycles, according to
• Bit 5:3 – ESRDLY[2:0]: SDRAM Exit Self-refresh to Active Delay
This field defines the delay between CKE set high and an ACTIVE command in a number of
Clk
PER2
cycles, according to
.
Table 27-17.
SDRAM row to precharge delay settings
RPDLY[2:0]
Group Configuration
Description
000
0CLK
Zero Clk
PER2
cycles delay
001
1CLK
One Clk
PER2
cycles delay
010
2CLK
Two Clk
PER2
cycles delay
011
3CLK
Three Clk
PER2
cycles delay
100
4CLK
Four Clk
PER2
cycles delay
101
5CLK
Five Clk
PER2
cycles delay
110
6CLK
Six Clk
PER2
cycles delay
111
7CLK
Seven Clk
PER2
cycles delay
Bit
7
6
5
4
3
2
1
0
+0x09
WRDLY[1:0]
ESRDLY[1:0]
ROWCOLDLY[1:0]
SDRAMCTRLC
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Table 27-18.
SDRAM write recovery delay settings.
WRDLY[1:0]
Group Configuration
Description
00
0CLK
Zero Clk
PER2
cycles delay
01
1CLK
One Clk
PER2
cycles delay
10
2CLK
Two Clk
PER2
cycles delay
11
3CLK
Three Clk
PER2
cycles delay