Figure 7-15. Nand Flash Timing Example; Bit Example Transaction - Sharp LH79524 User Manual

LH79524/LH79525 User's Guide External Memory Controller

7.3.2.2 16-bit Example Transaction

A quick example illustrates one way for software to handle 16-bit NAND Flash transac-
tions. This example shows a simple data Write to the NAND Flash, but Reads and Com-
mands work similarly. Figure 7-15 shows the timing generated by the following sequence.
With all control signals FALSE, the address of the location to be written in the NAND Flash
is placed on the LH79524/LH79525 D[15:0] pins ('A' in the Figure). Software, with the
proper signals on D[15:0], then programs a Write to location 0xCXXX10, causing ALE and
nFWE to go HIGH ('B'). With the same data on D[15:0], a write to location 0x4XXX10
causes nFWE to go LOW ('C'). Writing to location 0xCXX10 again drives nFWE HIGH,
which latches the address in the NAND Flash ('D'). Finally, to clear the interface, write to
address 0xCXXX00, forcing ALE to LOW ('E').
A B C D E
D[15:0] VALID
ALE
nFWE
LH79525-120

Figure 7-15. NAND Flash Timing Example

7.3.2.3 Address Examples
If nCS0 is used to connect 8-bit NAND Flash, use the following addresses:
• 0x40800000 — to read from NAND Flash
• 0x40800008 — to write address to NAND Flash
• 0x40800010 — to write command to NAND Flash.
If nCS0 is used to connect 16-bit NAND Flash, use the following addresses:
• 0x41000000 — to read from NAND Flash
• 0x41000010 — to write address to NAND Flash
• 0x41000020 — to write command to NAND Flash.
Note in the 16-bit addressing, the lower 24 bits have just been left-shifted one bit to com-
pensate for the right-justified addressing of the EMC.
Version 1.0 7-21