ESP32-WROOM direct external QSPI flash for mass production programming

[RMandR]

For ESP32-WROOM, is there any documentation or guidance on connecting and directly programming the ext QSPI flash chip instead of serial programming via esp32 chip and esp_tool.py?

Most QSPI chips these days support 100Mhz as opposed to much slower process of going through ESP32.

The datasheet for ESP32WROOM says:

"Pins GPIO6 to GPIO11 on the ESP32-D0WD-V3 chip are connected to the SPI flash integrated on the
module and are not led out."

Not sure if this means we can't connect to the ext SPI, or the pin mapping they used.

Appreciate your input.

-a

[ESP_Sprite]

I think you should be able to keep the ESP32 in reset (as in: make EN low) and program the flash if you have access to the SPI pins. If the module you have doesn't give you that, then well... I'd imagine all you can do is lift the can, and that's not very production-safe Note that from my experience with higher baudrates and USB flashing, you get diminishing results in trying to make the interface faster: at some point you're spending most of the time waiting for an erase or write cycle to complete. The absolute fastest way to get your flashed chips may actually be to not flash the chips at all but to contact sales@espressif.com: from a certain MOQ (iirc 1 reel) we offer pre-programming services, selling you modules with your own firmware already flashed into it.

[RMandR]

@ESP_Sprite thank you for your response.

Yes, the idea is to keep esp32 in reset and flash the EXT SPI using something like a SEGGER J-LINK that has support for e.g. Winbond flashes and can theoretically flash at 100Mhz (even at twice the current USB serial speed, we'll save many seconds per device).

Also, yes, we've seen diminishing returns when it comes to USB serial programming. pre-programming is great but not an option (keys and certs).

The modules we're using are ESP32-WROOM32-E and I was hoping to get a soft confirmation of EXT SPI pin mapping to module pins and the plan to continue routing them to the module pins.

regards,

-a

[WiFive]

ESP32-WROOM32-E does NOT expose spi flash pins.