
PRODUCT OVERVIEW
S3C2440A RISC MICROPROCESSOR
1-20
SIGNAL DESCRIPTIONS
Table 1-3. S3C2440A Signal Descriptions (Sheet 1 of 6)
Signal
Input/Output
Descriptions
Bus Controller
OM[1:0]
I
OM[1:0] sets S3C2440A in the TEST mode, which is used only at fabrication.
Also, it determines the bus width of nGCS0. The pull-up/down resistor
determines the logic level during RESET cycle.
00: Nand-boot
01: 16-bit
10: 32-bit
ADDR[26:0] (Address Bus) outputs the memory address of the corresponding
bank .
DATA[31:0] (Data Bus) inputs data during memory read and outputs data during
memory write. The bus width is programmable among 8/16/32-bit.
nGCS[7:0] (General Chip Select) are activated when the address of a memory is
within the address region of each bank. The number of access cycles and the
bank size can be programmed.
nWE (Write Enable) indicates that the current bus cycle is a write cycle.
nOE (Output Enable) indicates that the current bus cycle is a read cycle.
nXBREQ (Bus Hold Request) allows another bus master to request control of the
local bus. BACK active indicates that bus control has been granted.
nXBACK (Bus Hold Acknowledge) indicates that the S3C2440A has surrendered
control of the local bus to another bus master.
nWAIT requests to prolong a current bus cycle. As long as nWAIT is L, the
current bus cycle cannot be completed.
11: Test mode
ADDR[26:0]
O
DATA[31:0]
IO
nGCS[7:0]
O
nWE
nOE
nXBREQ
O
O
I
nXBACK
O
nWAIT
I
SDRAM/SRAM
nSRAS
nSCAS
nSCS[1:0]
DQM[3:0]
SCLK[1:0]
SCKE
nBE[3:0]
nWBE[3:0]
NAND Flash
CLE
ALE
nFCE
nFRE
nFWE
NCON
O
O
O
O
O
O
O
O
SDRAM row address strobe
SDRAM column address strobe
SDRAM chip select
SDRAM data mask
SDRAM clock
SDRAM clock enable
Upper byte/lower byte enable (In case of 16-bit SRAM)
Write byte enable
O
O
O
O
O
I
Command latch enable
Address latch enable
Nand flash chip enable
Nand flash read enable
Nand flash write enable
Nand flash configuration
* If NAND flash controller isn’t used, it
has to be pull-up. (VDDMOP)
FRnB
I
Nand flash ready/busy