Electronics > Projects, Designs, and Technical Stuff
DDR2 chip how slow can you go?
Yansi:
SDcard is already a managed NAND flash memory, isn't it? No wear leveling and bad block management required (the latter probably even not possible with an SDcard, as I think the ECC spare area sectors are not accessible? and the SDcard controller does all that required).
Bare metal NAND FLASH chip may be a completely different story.
//On windows, you use for example HXD.
nctnico:
--- Quote from: SiliconWizard on August 30, 2019, 08:21:14 pm ---I would not use a FS for that. It would add overhead, possible bugs and make the wear-leveling much harder to do without largely modifying the FS code.
--- End quote ---
Most SD-cards from sensible brands will do wear levelling. Otherwise the flash would wear out very fast for the area where the FAT is written to.
SiliconWizard:
--- Quote from: Yansi on August 30, 2019, 08:27:33 pm ---SDcard is already a managed NAND flash memory, isn't it? No wear leveling and bad block management required
--- End quote ---
Maybe you're right. Don't know how effective it is or if all SD cards are born equal (I would suspect not...)
Even if it's not for wear leveling, one benefit of writing data explicitely to consecutive sectors instead of writing it always starting at the same sector would be the ability to read back several past data blocks instead of just one. If you keep writing from the first sector, the SD card controller may write the data in different parts of the Flash for wear leveling, but you will never be able to access anything else but the last block.
Kilrah:
--- Quote from: nctnico on August 30, 2019, 08:34:49 pm ---Most SD-cards from sensible brands will do wear levelling. Otherwise the flash would wear out very fast for the area where the FAT is written to.
--- End quote ---
I don't know of any commercial card that does this, and yes the FAT area is what usually fails first for obvious reasons.
SOME industrial spec ones do it, but they're a niche and specifically marketed as such.
JohanHoltby:
I'm a test energier and this memory will be in a switch module which will be one of my products I will sell to my clients. It's a modular system of startkabel modules. Each sub module will ha ve 40 channels 32 in from TPs and 8 out (to the 8 rows). Each connection will have monitoring for safety and debugging for current and voltage. I want to have the data for all channels for the last 8 seconds. So when the test is stoped then I can go around and check what happens leading up to the break in the system to know what's happening and why. No more reruns to try to find the problems so streaming is not needed. No more broken equipment du to malfunctioning DUTs since the system can set the safty levels for each value. The STM32 chip has 4ADC with 5Msps each.
Regarding my lack of knowledge I have to agree on this topic since I have not worked with any other memory modules than EEPROMs and SD cards. The layout and exact schematics will be done by a small design house which have good knowledge of high speed communication but as some pointed out I need to know what I want ;).
When I did look in to the Flash modules I noticed that I will need to replace the SD cards two times every year for a 128Gb SD card. And since this system will be deployed by an EMS overseas often I don't have the luxury of replacing SD cards. SO about 10 years of operation would be great.
So right now I hink of going with SDRAM or SRAM.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version