How FlexSPI talks to a QSPI NOR on the i.MX RT1062: the two access paths, the LUT, the sampling clock that caps your frequency, and how to prove you run at full speed. Read speed is checked against the bus, write speed against the flash datasheet.
Five lessons from taking an i.MX RT control unit from first boot toward production: the bootloader that hides your SDRAM setup, the flash size nobody measured, writing the flash you execute from, firmware updates as a protocol, and surviving the power cut.
What each IOMUXC pad-control field on the i.MX RT10xx actually does, how to derive its value from the schematic and the protocol spec instead of trusting generated defaults, and a microSD interface as a worked example.