Flash QE Bit Fix for RP2350 Boards with PSRAM locking up when overclocking.

A utility that sets the Quad Enable (QE) bit in the flash chip's Status Register 2. This is a permanent fix for RP2350-based boards with PSRAM that use non-Winbond flash chips (e.g. Puya), which lock up when overclocking the RP2350 due to the QE bit not being set from factory.

For example, some batches of the Waveshare RP2350-Pizero ship with Puya flash and lock up when overclocking.

Winbond - working	Not working

Boards without PSRAM are not affected by this issue.

See also fhoedemakers/pico-infonesPlus#191

Usage

1. Build the project using the Pico SDK (requires pico-sdk with RP2350 support):

   mkdir build && cd build
   cmake ..
   make

2. Flash the resulting FLASH_QE_SET_1.uf2 onto your board via UF2 bootloader.
3. The program will set the QE bit and print the flash status registers over USB serial.

A prebuilt UF2 is available in the uf2/ directory.

Caveat

Affected boards (RP2350 + PSRAM + non-Winbond flash) cannot be overclocked above 252 MHz, even after applying this fix.

Credits

• Original fix by Waveshare.
• Thanks to szuping for testing and sharing the solution.