Yes, the flash chip integrated into the RP2354 is the W25Q16JV which supports standard SPI, you can refer to that chips datasheet for details.I assume you can drive single-pin SPI to program the flash, just more slowly, right ?
And does the UART boot loader allow you to program the flash via serial ? Or is it just SPI that has write access ?
The UART boot loader specifically doesn't allow writing to anything except SRAM, however you can load a 2nd stage bootloader + payload that then writes that payload to flash. I believe it's also possible to write that bootloader in a way where it would receive data over UART and then write it to the flash in SPI mode, ensuring that the SD3 pin is high so /HOLD mode isn't triggered.
Hard to test right now, since the RP2354 chips are still not available (outside of a few samples that were available at jlcpcb for some time).
Statistics: Posted by Tharre — Thu Jun 12, 2025 2:07 am