![Samsung S3C2501X User Manual Download Page 220](http://html.mh-extra.com/html/samsung/s3c2501x/s3c2501x_user-manual_340828220.webp)
S3C2501X
MEMORY CONTROLLER
5-5
5.4 BUS INTERFACE SIGNALS
The bus interface signals transfer information between the S3C2501X and external memory device.
These divide into address and data which used commonly, SDRAM interface signals for SDRAM and memory
device interface for ROM/SRAM, etc.
For detail description for the bus interface signals, refer to the table below.
Table 5-2. Bus Interface Signals
Signal Name
Pins
Active
I/O
Description
ADDR
24
HIGH
O
Specifies the physical address of the external device
DATA
32
HIGH
B
Specifies data of the external device
B0SIZE
2
HIGH
I
Specifies data bus access size for the Bank 0
nOE
1
LOW
O
Specifies read/write state from S3C2501X. When
S3C2501X read from ext I/O device, nOE’s value is
1’b0.
nRCS
8
LOW
O
Specifies which ext I/O device is selected.
nEWAIT/nREADY
1
LOW
I
Signal be controlled from ext I/O slow device to delay
cycles in data read and write.
HCLKO
1
HIGH
O
S3C2501X system clock out
CKE
1
HIGH
O
Clock enable for SDRAM
nSDCS
2
LOW
O
Chip select strobe for SDRAM
nSDRAS
1
LOW
O
Row address strobe for SDRAM
nSDCAS
1
LOW
O
Column address strobe for SDRAM
nWBE/nBE/DQM
4
LOW
O
Write byte enable
nSDWE/nWE16
1
LOW
O
Write enable for ROM, SRAM, Flash that have 16bit-
data width and SDRAM.
XBMREQ
1
HIGH
I
External Master bus request
XBMACK
1
HIGH
O
External bus acknowledge
NOTES:
1. O = Output from the S3C2501X.
2. I = Input to the S3C2501X.
3. B = Bi-direction.
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 ...