Nikkei Electronics Asia -- May 2009
Solutions - Web Articles
Managed NAND with Boot Options for PMP/PND Designs

May 21, 2009 15:01 Nikkei Electronics Asia

Non-volatile memory provides a variety of functions in a processor-based system such as PMP/PND devices. One of the most critical is to provide the initial firmware the processor uses in system initialization (boot) process. However, both NAND Flash - with its interface challenges; and NOR Flash - with its relatively low density, are unsatisfactory for use as a single non-volatile and bootable system memory solution.

Meanwhile, not a single type of these Flash memories is able to meet all the requirements for PMP/PND designs, which include low cost, low power and high storage capacity. However, Managed NAND offers an alternative. Managed NAND devices feature an on-chip controller which handles the vendor-specific algorithms for wear-leveling and write/erase timing, as well as the memory management functions of the NAND memory. This eliminates the software overhead associated with using NAND memory and allows Managed NAND devices to offer a standardized, vendor-agnostic interface to the system processor.

The critical bootable feature is addressed on Managed NAND by: (1) a hardware component which bridges the processor and memory to make it look like a simple ROM to the processor; and (2) an initial program loader routine which performs minimal CPU initialization and transfer the boot loader code from the memory to the processor. These two are combined to allow the Managed NAND to serve both as program and data storage, which offers cost savings, design simplification, and the capability to handle increased memory capacity in future.

by Kathleen Murchek,
QuickLogic Corp

Full article:
http://techon.nikkeibp.co.jp/NEA/solutions/0905002.pdf

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