External Memory Question

Hi there!

I am currently working on a product around the sitcore SC20100S.

The problem I am running into is lack of memory, so I am planning on adding extra external memory to the soc.

Is there any documentation as to how to connect a chip and what chip to use? I am unable to find it. I was hoping to be able to use this chip:
https://www.digikey.com/en/products/detail/adafruit-industries-llc/4677/13148775?s=N4IgTCBcDaIIwFYwA4C0AWAbAdm6gcgCIgC6AvkA

It’s a quite standard external memory chip used on boards as ESP32 and Teensy 4.1.

Adding such memory will not increase your heap. If you need RAM then one of the SoMs with sdram is what you need.

Also, can you tell us what you are doing that needs the extra memory?

Thanks, Gus.

The thing I wan to do is add the same sdram as on the SoMs. Is it possible to add sdram on the LQFP variant or do I need the BGA package? Are the schematics for these modules open source?

I am working on a project that requires to be very cheap. This is why I went with the soc. The product however needs to be able to remotely update it’s firmware and software so I am in need of extra RAM.

The extra pins are needed for sdram

Is the SC20260B available for purchase anywhere? I am unable to find it at Mouser and DigiKey

It is special order for high volume customers. If you are only buying it to save money vs buying SCM20260N then you are not going to be saving. But if you need it because you need a very tiny setup and you have volume behind it then we can talk directly and discuss options.

Either way, fell free to give us a call to discuss your needs.

Is there any market for a device in between the SCM20100E and the SCM20260E/N. Something based on the same MCU as the 20100E, Ethernet PHY but include the 32MB Ram, no TFT or camera. 8GB Flash could be added to the customer board only if required (Unless there was room on the SOC.) I think 32MB Ram should be available as a BGA.

I like the idea of the SCM20100E for a cellular IoT project but without the RAM remote firmware updates aren’t available.

Then your question shouldn’t be about RAM but about the ability to do full IFU on the small chips. This is on the top of our list now https://github.com/ghi-electronics/TinyCLR-Libraries/issues/589

Stay tuned

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That’s awesome! Looking forward to that.

I am in the proces of developing a lot of products for the marine industry and full IFU will be awesome because those ships can be on the other side of the continent :slight_smile:

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I don’t think you could use the SCM20100E BGA with external ram as the required pins for the FMC are only available on 144pin packages and above…

If I read the table in the datasheet the FMC should be available on the 32H743VI. (https://www.st.com/resource/en/datasheet/stm32h743vi.pdf)
Now I didn’t go through to see if it is shared with other more critical pins. To maintain the small size the RAM would need to be BGA which I haven’t looked into.

Like @Gus_Issa said, if firmware updates can safely be done without the external RAM then that solves the primary issue.

Yes the FMC is available on 100 pins but it doesnt have the full allotment of pins necessary for SDRAM

e.g. it doest have FMC_A0, FMC_A1 etc which are needed.

Well that answers that, thanks for getting into the details.