WROVER SRAM/PSRAM misunderstanding

[unknow005]

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]

I just found this article: https://thingpulse.com/esp32-how-to-use-psram/

[unknow005]

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 Or is the article outdated and is it possible to use all of 8 MB?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]

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.