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AMD GeodeTM Solutions
External NAND Flash Memory
Circuit on IDE Interface
1.0 Scope
This application note describes an external NAND Flash Additional decode circuitry is required to have either a hard
module and explains how to connect it to an AMD GeodeTM disk and a NAND device, or multiple NAND devices on the
Solutions based system via its IDE interface. The GeodeTM same IDE channel. The decode could exist as a GPIO sig-
CS5535 and CS5536 companion devices both feature nal and its complement to gate the CS0# signals to the
NAND Flash controllers, however, this Flash on IDE solu- hard disk and the NAND device. Figure 2-2 shows a exam-
tion yields better performance. The NAND Flash module in ple of how this could be realized.
this application is used by the system for the operating sys- VCC
tem. The NAND device is not used for BIOS storage.
Note: This is revision B of this document. The change
from revision A (dated July 2005) is the addition of
the second sentence in the scope for clarification. GPIOx CS0# to IDE
IDE_CS0# Hard-disk CS0#
2.0 Discussion CS0# to
The NAND flash module connects to the AMD Geode NAND CE#
device's IDE interface to provide higher data throughput
than can be achieved using an ISA bus interface. Figure 2- Figure 2-2. Additional Decode Circuitry
1 shows a typical application that is functional in a system
where the NAND device is the only device on its IDE chan- The addressing for the various ports on the NAND device
nel. Two possible architectures that support this scheme are dependant upon which IDE channel the NAND device
are: is connected to. Table 2-1 lists the NAND device ports and