How can I connect Gbit SDRAM to STM32F429?

[bestamigunay]

Hello,

I would like to connect Gbit SDRAM to STM32F429 MCU. When I look at the STM32 FMC memory map, it has two 256 Mbytes area for SDRAM. As far as I understand, I can connect up to 4 Gbit SDRAM. However, SDRAMs have maximum 512 Mbit size.

1) Is it possible to connect multiple (2 or 4) 512 Mbit SDRAM (AS4C32M16SB) to the MCU?

2) If yes, how can I connect multiple SDRAM?

Thank you!

[Tesla DeLorean]

Parts come in all sorts of configurations. There are likely many workable combinations.

A 32-bit data bus could come from 8 4-bit devices sharing a common address and RAS/CAS, with byte lanes associated with pairs of SDRAMs serving high/low nibbles in each lane.

Pairs of 16-bit wide might be more workable/practical.

[Tesla DeLorean]

Anyway, if you need boatloads of RAM, you might consider if this is the right platform.

As I recall random access on the F4 for SDRAM is 6x slower than internal SRAM. The part also has NO caching mechanism architected into the design, making it a huge choke point.

[bestamigunay]

First of all, thank you for your answer. AS4C32M16SB (512 Mbit) has 16 bit data and 13 bit address signals. If I want to use two of them in order to get 1 Gbit SDRAM, should I use same data and address signals but different clock and chip enable signals for each AS4C32M16SB? Also, if I want to use 4 SDRAM (AS4C32M16SB), how should I connect data and address signals and enable signals?

[bestamigunay]

For total 2 Gbit SDRAM, is this configuration OK? Also, if I want to use 4 Gbit SDRAM, what should I do?

[bestamigunay]

For total 4 Gbit SDRAM, is this configuration OK?