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MEMORY CONTROLLER
S3C2501X
5-48
Table 5-25 SDRAM Configuration Register (Continue)
Reg0
Bit
Description
R/W
Default
value
XW
[0]
External data bus Width
0 = external bus width is 32 bit.
1 = external bus width is 16 bit.
R/W
0
AP
[1]
Auto Pre-charge control for SDRAM accesses
0 = Auto pre-charge
1 = No auto pre-charge
R/W
0
CL
[3:2]
CAS Latency
00 = Reserved 01 = CL: 1 cycle
10 = CL: 2 cycles 11 = CL: 3 cycles
R/W
11
D1[1:0]
[5:4]
SDRAM device Density of bank 1
00 = 16M-bit SDRAM memory devices.
01 = 64M-bit SDRAM memory devices.
10 = 128M-bit SDRAM memory devices.
11 = 256M-bit SDRAM memory devices.
R/W
00
D0[1:0]
[7:6]
SDRAM device Density of bank 0
00 = 16M-bit SDRAM memory devices.
01 = 64M-bit SDRAM memory devices.
10 = 128M-bit SDRAM memory devices.
11 = 256M-bit SDRAM memory devices.
R/W
00
RP
[9:8]
Row Pre-charge time
00 = RP: 1 cycle 01 = RP: 2 cycles
10 = RP: 3 cycles 11 = RP: 4 cycles
R/W
11
RCD
[11:10]
RAS to CAS delay
00 = RCD: 1 cycle 01 = RCD: 2 cycles
10 = RCD: 3 cycles 11 = RCD: 4 cycles
R/W
11
RC
[15:12]
Row Cycle
0000 = RC: 1 cycles 0001 = RC: 2 cycles
…
1110 = RC: 15 cycles 1111 = RC: 16 cycles
R/W
1001
RAS
[19:16]
Row Active time
0000 = RAS: 1 cycles 0001 = RAS: 2 cycles
…
1110 = RAS: 15 cycles 1111 = RAS: 16 cycles
R/W
1001
[31:20]
Reserved
–
NOTES:
1.
Software should not write to configuration register when the SDRAM engine is busy. The SDRAM engine status bit,
BUSY in command register, can be used to check if the control engine is idle.
2.
We recommend that the auto pre-charge should be disable by asserting "1" on the AP of Reg0 when the page hit ratio is
more than 50%.
Summary of Contents for S3C2501X
Page 18: ......
Page 275: ...MEMORY CONTROLLER S3C2501X 5 60 NOTES ...
Page 289: ...I2C CONTROLLER S3C2501X 6 14 NOTES ...
Page 373: ...GDMA CONTROLLER S3C2501X 9 24 NOTES ...
Page 435: ...I O PORTS S3C2501X 12 12 NOTES ...