Max size of Flash memory that can be used? ESP32

chibill
Posts: 10
Joined: Wed Mar 27, 2019 2:48 pm

Max size of Flash memory that can be used? ESP32

Postby chibill » Fri May 24, 2019 4:21 am

I am wondering what the max size of flash memory that can be attached to the ESP32. Like I know only 16MB can be mapped at once but does that mean you can have a large flash and just map a different 16MB to access more of the chip. (Losing access to that first 16MB of course until you map back to it.)

Also if you can do that is there a way to use a large flash and get alot more program memory space?

jcsbanks
Posts: 294
Joined: Tue Mar 28, 2017 8:03 pm

Re: Max size of Flash memory that can be used? ESP32

Postby jcsbanks » Fri May 24, 2019 8:10 am

It seems that 16MB flash and 8MB PSRAM can be mapped from, but the windows are 4MB or about 3.2MB for instruction access. 11.5MB should be able to map into instruction address space on 32 bit alignment, but I could not read back correct values using mmap and could not find reported success using registers so I mmap in chunks to data address space to use all the flash at high speed (FATFS is too slow). Did you successfully map greater than 4MB contiguously?

ESP32-S2 looks like it will be a welcome improvement.

chibill
Posts: 10
Joined: Wed Mar 27, 2019 2:48 pm

Re: Max size of Flash memory that can be used? ESP32

Postby chibill » Tue May 28, 2019 2:38 am

I only have an ESP-WROOM to use. I was asking to figure out if you could use say a larger flash and just dynamically swap which blocks are mapped into the address space.

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