Electronics > Microcontrollers

512 Megabyte sdram for stm32

<< < (4/4)

hans:
Well solutions have been given to you. Get 2 groups of 4x 512Mbit SDRAM chips with 8-bit data bus, and find someone that will torture themselves to route the PCB for it, if at all possible. If you have searched extensively for larger SDRAM chips and found 0 results, then its unlikely a 4Gbit SDR SDRAM chip exists, off the shelf, in 1 package, because there is no large scale demand for it. But it looks like you're pretty fixed to the parts chosen, so that also means the answer is pretty fixed.

Higher density memory chips have moved to DDR, DDR2 etc. buses which allow for reasonable access times to the whole memory array. At 512MB and a 100MHz SDR 32-bit bus (if you happen to get a working PCB layout for that), you're looking at 1.2+ seconds to do a full read of the array, neglecting access times, maximum burst sizes, memory refresh cycles and protocol/addressing overhead, which will probably increase it to 1.5 seconds or so. This is the reason for the "why?". I think most applications wanting 512MB would also want/need the memory bandwidth to support it.

If all you need is capacity, you could look in other ways of emulation. Multiple PSRAM chips that work over QuadSPI (note that ST's memory-mapped QuadSPI controller is meant for read-only modes only  IIRC, e.g. FLASH). Or crazy idea: a 1TB SD card and trust the wear leveling. Even the most trash quality FLASH with only 300P/E cycles would last almost 1yr when it's continuously written at 12.5MB/s (SDIO bus 50MHz).

nctnico:
A better option would be to use a SoC which has a DDR memory interface. You don't need to run Linux on it in case the task isn't demanding. U-boot has all the features you need to create a lightweight platform.

seyedsaeed:
Thank you very much to everyone.
I just realized.
I have to use 8 pieces of RAM in parallel.

Siwastaja:

--- Quote from: hans on June 11, 2023, 04:09:27 pm ---Get 2 groups of 4x 512Mbit SDRAM chips with 8-bit data bus, and find someone that will torture themselves to route the PCB for it, if at all possible.

--- End quote ---

Why do you think it's torture or difficult? Usual job for a PCB designer, multi-RAM-chip modules have always been commonplace and somebody designed them. Given this project is super important super secret scientific instrument, they should be able to afford as many PCB layers as required, not to mention lasered microvias, buried, blind vias etc., which make the layout work even easier.

Navigation

[0] Message Index

[*] Previous page