WROVER SRAM/PSRAM misunderstanding

unknow005
Posts: 20
Joined: Wed Dec 19, 2018 6:16 am

WROVER SRAM/PSRAM misunderstanding

Postby unknow005 » Sat Dec 03, 2022 4:12 pm

Dear community,

I allways used ESP32-WROOM module. But some my projects uses video buffers with size in hundreds of kB of SRAM. The SRAM limit of this module is 512 kB which is crazy low. But I came across the ESP32-WROVER module which has the same size of SRAM (512 kB) but it also has PSRAM in megabytes. I thought this memory automatically expands the SRAM ... so I could use a much larger video buffers in my projects. But it doesn't work that way for me. My question is: what is the PSRAM even for? Is it possible to "merge" it with the SRAM address space to make 512 kB + 8 MB size of SRAM?

Thank you!

unknow005
Posts: 20
Joined: Wed Dec 19, 2018 6:16 am

Re: WROVER SRAM/PSRAM misunderstanding

Postby unknow005 » Sat Dec 03, 2022 6:41 pm


unknow005
Posts: 20
Joined: Wed Dec 19, 2018 6:16 am

Re: WROVER SRAM/PSRAM misunderstanding

Postby unknow005 » Sat Dec 03, 2022 7:15 pm

But still... is the 4 MB of PSRAM maximum which can be addressed by ESP32? Or is the article outdated and is it possible to use all of 8 MB?

ESP_Sprite
Posts: 8926
Joined: Thu Nov 26, 2015 4:08 am

Re: WROVER SRAM/PSRAM misunderstanding

Postby ESP_Sprite » Sun Dec 04, 2022 5:55 am

There is a 'himem' API that allows for some banked PSRAM access, but you still can only get access to 4MiB at one time. If you need a larger address space for PSRAM, later chips (ESP32S2 and ESP32S3) have that.

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