NAND flash in embedded designs?

I've used NAND (8MByte) in a somewhat more demanding application, but it hasn't been out there for 10 years yet. Similar to your intended application, I had a small-n-cheap bootloader OTP EPROM that loads the main firmware into RAM off the NAND flash. The difference in my case is that the remainder of the NAND was used for storage of data files which were rewritten quite frequently.

This was convenient because I put a SmartMedia slot on my device, and developed the initial firmware using removable media. When it went golden, I just took off the socket and added the chip.

That company is out of business, so now I'll never know if it would last 10 years, but in product returns over the course of two years I _never_ saw a single bad "decayed" bit generated after initial programming.

yes. I use large block 256MB NAND flash in a super miniature design. I have found it to be extremely dependable. After bad block management. I do not do wear leveling because my application does not require it.

Stick with SLC (single level cell) NAND rather than MLC (multi-level cell). Multilevel Cell encodes more than one bit in a "cell" - meaning multiple threshold voltages than simple on/off. It therefore needs a better ECC than the simple "parity of different selections of bits" of conventional ECC. (which is not terribly rigorous, and corrects single bit errors).

In fact, I'm about to post a question on multi-bit ECC's, as market pressures may not give me a choice not to support MLC devices...

Rufus

BTW there are NAND FLASH devices coming down the pipe which will contain a control on-chip, so much of the mapping and error correction will be done for you. Look for iNand and OneNand (I think those are the names)

Thanks for the input all. Spansion has a device that is NOR flash with a NAND interface. The problem is that it appears geared towards consumer apps, and we'd have to buy an extremely large quantity. The other links are helpful.

Thanks again. // -Joe