IS61WV25616MEBLL and IS64WV25616MEBLL are recent Muxed PSRAM from ISSI. I would like to use these with an LQFN100 STM32H750VBTx to avoid complicated routing with SRAM and going to a larger LQFN or BGA package.
The FMC of this MCU supports Muxed PSRAM. I am trying to understand if the part is compatible by comparing the datasheet with what I see in CubeIDE.
I do not understand:
- The data sheet has 16 Muxed Address/Data lines but it also has two additional address lines A16, A17 (PSRAM)
- Byte Enable (CubeIDE)
Questions:
- Do I configure the data as 16-bit or 18-bit? It seems to have 16-bit data and an 18-bit address.
- In CubeIDE I noticed that when I select the Byte Enable checkbox, I get two pins: FMC_NBL0 and FMC_NBL1. Should I connect these two pins to A16 and A17?
- Any suggestions on PSRAM parts that are known to work well with STM32H7?
Hello @semi and welcome to the community,
These are my answers:
- Do I configure the data as 16-bit or 18-bit? It seems to have 16-bit data and an 18-bit address.
-> Only the the data/address 0 to 15 are multiplexed in Muxed mode. The address lines A16 to A23 on the 100 pins package are not.
So what you need to do is to connect ADQ0 to ADQ15 of the memory to FMC_D0 to FMC_D15 and A16,A17 to FMC_A16 and FMC_A17.
- In CubeIDE I noticed that when I select the Byte Enable checkbox, I get two pins: FMC_NBL0 and FMC_NBL1. Should I connect these two pins to A16 and A17?
FMC_NBL0 and FMC_NBL1 are used to select the byte to read and write i.e. lower byte/upper byte. These FMC pins need to be connected respectively to LB# and UB# of the memory.
- Any suggestions on PSRAM parts that are known to work well with STM32H7?
Not specifically Muxed memories are used on our boards, but you can refer to the Eval board schematics on this link: IS61WV102416B memory is used:
Hope I answered your questions.
