Thank you for responding to my post. I will explain. We are using the RP2040 and W25Q12_IVS flash memory on a series of PWAS that we designed for our product. We have been using this design for over 2 years. In the design, the QSPI pins of the RP2040 are connected directly to the flash memory. In addition, a USB boot strap circuit is connected to the flash memory, which has a jumper arrangement to ground CS (chip select), enabling the BOOT SELECT mode when the jumper is present. This arrangement is exactly what is on the PICO board. When programming a new chip by installing the jumper and then applying power, it forces the chip into Boot mode, where it functions as a USB drive. This function works correctly on the failing chips. At this point, we drop in RPI_PICO_20250911-v1.26.1.uf2. Which appears to be correctly installed. We remove the jumper and power cycle the chip, which normally causes a USB connection (FS MODE) where we can install the application program. This step is what fails on the fallout chips. The chip never goes to the USB mode, CS remains low and the chip doesn’t do anything. This failure did not start until recently, but it has the same fallout from two distributors. What I am asking is, has anybody seen this problem, and if so, what did you do about it? I don't believe all these chips are bad, but we have checked everything and isolated this to testing all chips with a known good board.
Statistics: Posted by kenc55 — Wed Nov 26, 2025 7:24 pm