Best memory type for data logging

Question

I'm gonna design a board which data logging it's mandatory! I don't think that i have sufficient space in pcb for large parts but i want an embedded flash (dedicated IC). For handling unexpected power downs the system must storing data every time which is determined by some interval value (seconds). Data have string format with undefined lenth. And i need to store that data in an embedded flash memory. Data comes from, sensors and other peripherals such as power supply monitoring.

• Who memory type is best for that purpose? (NAND or NOR)?

I will glad with a >4MB memory capacity. In a little research i find that NAND flash have small amount of pages with large capacitance and this will consumes more W/E cycles.

-Thanks!

Answer 1

If you're looking for something which can withhold many write cycles you might want to to look at FRAM (e.g. from Cypress). Basically unlimited Write/Erase cycles. Of course, this comes at a cost. If you're looking for large storage, go for NAND but make sure that you do not write to the same sector/page again and again.

Answer 2

I realize you mentioned using a dedicated IC, but I believe the easiest way to add a device for data logging in a reasonably small space is to use a microSD card. The connection to the microcontroller is a four wire SPI bus (CLK, SDI, SDO, and CS). Because of their high volume, they are very inexpensive -- 8 GB for $5 on Amazon, probably less on eBay. These happen to use NAND flash, but that's transparent to the user.

You don't need an operating system, you can just write to it as individual sectors. Because the space is so huge, there is no issue of wearing out the card. The spec for the SPI interface to SD cards is publicly available, and there's also lots of code for writing and reading to the card around.

If you want to add the code to implement a FAT file system, then you could remove the card and read it in a PC. There's a lot of code around to do that also.