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I believe i might undestand what happens (to some extent) The code which detects PSRAM chips are switching them to SPI by issuing 0xF5 (exit QPI mode), then resets chips and uses 0x9F (read ID bytes) to detect is it is PSRAM or not, but command 0x9F as per Adafruit's datasheet is "similar to...

on Arduino IDE it is not reproducible because it fails only if startup.c is patched with a clock change to 120MHz. if i change clock in setup() or loop() before doing anything, the issue is gone. that's a mystic bug tho. no need to investigate and i'm not asking you to do so. still, i believe...

i didn't mean that code posted is a complete testing. i only say that in my case i have this issue with as little as 16K of data (the rom content is in another file). if asm commands are removed it doesn't make any error because of cache of course, though i only undertand what 'dmb' does yet...

Well, long story short: I got two 4.1s: Name it Unit1 - no ethernet one and have two Adafruit PSRAMs installed, currently is soldered to a prototype. The PSRAM test sketch passes on all frequencies including 133MHz and below (120MHz, 110.77Mhz, and default 88MHz is what i tried) Unit2 - one...

I think i know how to distinguish write/read failures. 1) Copy array with default slower 88MHz clock - verify data is same 2) Change clock to faster 3) Try to reproduce read failure 4) Copy array again with faster clock 5) Switch to default clock and verify data is same, if not - write failure...

Actualy there is a 16Kb rom in uint8_t array which i initially used (source generated with Python from actual file) to check if signals are ok, an it is located in the fastest (tight coupled) memory. Then as a next step i added EXTMEM array, and copied data over to it (with a very bold approach...

Hey, i want to mention that PSRAM memtest provided is not completely trustful and may say "all is fine" while it is really not :) It costed me a couple of hours until i figured it out btw. I'm working on a hobby project which will read/write the data to some 5v TTL bus (LVC4245a translators were...