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External SPI RAM and eMMC on ESP32-S3
Posted: Mon Jul 17, 2023 1:44 pm
by dmrsim
Hello,
I'm using ESP32-S3 and I have to use an External SPI RAM.
On my circuit I have and eMMC that I use for storing data, can I use it also for External SPI RAM??
If yes, How can I do it?
Thanks!
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Tue Jul 18, 2023 8:29 am
by RathiSonika
Yes, you can use External SPI RAM and eMMC together on ESP32-S3.
For external SPI RAM (PSRAM) connection please refer to esp32-s3 datasheet (
https://www.espressif.com/sites/default ... eet_en.pdf, Section 2.7). For eMMC connection you should use any other available GPIO.
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Tue Jul 18, 2023 10:24 am
by dmrsim
Hello RathiSonika, thanks for your reply!
I'm in throuble during the configuration.
On my project I have 16 GB eMMC, but in the datasheet I see that: "e. ESP32-S3 supports up to 1GB of external flash and RAM".
Can i do it anyway?
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Tue Jul 18, 2023 11:59 am
by RathiSonika
Well, I did not get your exact question, can you please explain it again?
If you want to use 16GB eMMC for storing data along with 1GB external RAM then it’s possible.
But if you want to use 16GB eMMC as external RAM then it’s not possible.
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Wed Jul 19, 2023 1:00 am
by ESP_Sprite
dmrsim wrote: ↑Tue Jul 18, 2023 10:24 am
On my project I have 16 GB eMMC, but in the datasheet I see that: "e. ESP32-S3 supports up to 1GB of external flash and RAM".
Note that the 1GB of flash refers to the SPI flash that contains your application code. If you don't need to run code off it (or memory map it in any way, to be more specific), you can connect whatever size or type of flash you want to the ESP32, providing software supports.
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Wed Jul 19, 2023 5:51 am
by dmrsim
I apologize if I explained myself badly.
In our project, we have to use a lot of RAM.
The problem is that in out final PCB we have a 16 GB eMMC(for data storing).
The question is: Can we use the 16GB eMMC also as RAM?
Re: External SPI RAM and eMMC on ESP32-S3
Posted: Wed Jul 19, 2023 5:59 am
by ESP_Sprite
dmrsim wrote: ↑Wed Jul 19, 2023 5:51 am
I apologize if I explained myself badly.
In our project, we have to use a lot of RAM.
The problem is that in out final PCB we have a 16 GB eMMC(for data storing).
The question is: Can we use the 16GB eMMC also as RAM?
No:
- eMMC cannot be memory mapped
- even if it would be able to be memory mapped, using flash memory like eMMC as RAM is a Very Bad Idea because of slowness, erase blocks, wear levelling etc.