What kind of chips can I connect to QuadSPI bus

[papageno]

Hello dear experts,

Reading the ST literature abour QuadSpi, I noticed that they only mention the flash as available peripheral chips on the QuadSPI Ibus. i would like to increase the amount of RAM on the stm32F446RE to create a buffer when writing to microsd card in order to avoid some potential latency problems. Do you think it is possible to use a psram chip (APS1604M-3SQ QSPI PSRAM ) from apmemory on the Qspi bus ?

Thank you for your help and advices.

pap

[Harvey White]

I did a cursory check through Mouser, and it looks like the STM32H7A3ZIT6 would fill the bill. What I need is a lot of memory (I do graphics and most everything is packet driven), I need the TQFP-144 package for the pinouts, and TQFP for a package I can actually solder. While SDRAM is available with the FMC interface, the board layout is nasty, even with a 4 layer board (trying to equalize track length). I've got 22 or 33 ohm resistors in series to minimize ringing, a ground plane, and three signal layers (with ground pours).

I'll be using the QSPI interface, which while slower, can be better behaved (I hope). I'm also using an Epson S1D13517 chip. Uses external SDRAM (already have that working and drivers for it). But since you can't read from the chip, more memory is useful for read/modify/write operations.

Already have drivers to handle memory mapped extended memory (and works with FreeRTOS).

Any suggestions? And thanks for your help, nice to get another viewpoint.

[Alex - APMemory]

With the STM32H7, my RAM suggestion would be to investigate OPI APS6406L, APS12808L, APS25608N, APS51208N in BGA24, 11 signal pin. This will be same performance as SDRAM / FMC but with uncomparable less pin count and power...

https://www.mouser.de/c/semiconductors/memory-ics/dram/?q=apmemory&package%20%2F%20case=BGA-24

Alex

[Harvey White]

BGA chips are a non-starter. I assemble my own boards and can't handle BGA (and don't really want to). I could design them, but doing it? I don't care to. Getting the board house to put parts on would be, I think, a bit more expensive than I want especially on a first design iteration. If I can find any of these in a more amenable package, I'll give it a try. (Don't think that the option exists, though).

May have to stick with the SO-8 package and take a performance hit.

Thanks

[Harvey White]

Looks as if nobody makes OctoSPI memory in anything but BGA packages, according to Mouser.

Oh, well...........

Thanks

[Alex - APMemory]

You are right, Octo SPI is only BGA or WLCSP.

I agree QSPI SOP8 IoT RAM is a very simple and an easy to use solution (https://www.mouser.de/c/?q=QSPI%20SOP8). However for QSPI SDR & high performance STM32, you need to wait next MCU. In short term, if you could use Low Power Series (L4P5, L5, U5), then QSPI SOP8 already works full spec.

Alex

[Harvey White]

I had designs that used the F767, and the F446, and also the LK432. These were on Nucleo boards, and the hardware was designed to be a daughter board. As in every design, the demands of the design tended to overreach the processor, hence the additional RAM (graphics eats RAM, of course). With the higher performance you get from LTDC, you need extra mapped RAM. Tried SDRAM added to a Nucleo144 board (F767) and that was unstable. I had no real control over where the lines went on the Nucleo board, as well as whatever the IDC connector did to the signal.

That spawned a design with the F767 chip itself, which, because of chip shortage, was designed but never made. Needed a 4 layer board to do it.

The latest chip shortage had only the L5 chip available (and not any more.....), so I did a design with them. That got me looking at the QSPI RAM, which led to my part in this discussion.

However, the L5 chip is pin limited in a 100 pin package (all that was left), so I looked for another processor to order, and the H7A3 chip was reasonably priced, in the right package, and so on.

I've already shifted new designs to the H7 and L5, so the QSPI memory is a viable alternative. The H7 has yet to be delivered, though, but I can do a lot with the L5 series just as is. (I get an indirect interface I8080 style graphics chip that does multiple page TFT VGA, good enough).

Thanks.