Electronics > Microcontrollers

512 Megabyte sdram for stm32

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seyedsaeed:
Hi
Please, introduce 512 Megabyte SDRAM for stm32h755

langwadt:
I think the biggest SDRAM is 512Mbit, you'll need 8 chips or an old RAM stick

Georgy.Moshkin:
Have you looked into IoT RAM or PSRAM? It's not what are you looking for, but maybe worth considering. There are 512 Megabyte options in a small low pin count packages by different manufacturers, options are limited by low voltage logic levels, but there are 3V too.
https://www.st.com/en/partner-products-and-services/iot-ram-spi-qspi-psram.html

hans:
That ST part can't even map or control 512MB of SDRAM, I think:


--- Quote ---13-bits Address Row, 11-bits Address Column, 4 internal banks: 4x16Mx32bit
(256 MB), 4x16Mx16bit (128 MB), 4x16Mx8bit (64 MB)

--- End quote ---

2^13 * 2^11 = 16M addressing capability. At 32-bit bus width thats 64MByte per bank.
You'll need to connect 4 banks to address 256MByte.

But routing a 32-bit data + 13-bit address bus to 4 SDRAM packages doesn't sound that fun, but should be possible.
The old 144 or 168-pin SDRAM standard use 8 banks and thus a 8x8-bit = 64-bit data bus, so you'll lose half the memory capacity of those sticks.
The 72-pin SDRAM DIMMs have a 32-bit bus, but I haven't seen those in high capacity.

seyedsaeed:
FMC memory Banks

SDRAM controller

 I discover only one sdram with name MT46H64M32LF

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