At 133 MHz in Quad I/O mode, the S25FL128LAGMFV010 transfers four bits per clock cycle on the data lines.
Programming and interface notes
Programming the S25FL128LAGMFV010 over SPI follows the standard JEDEC SPI NOR command set extended for Quad I/O and QPI. The device supports the usual program, erase, and read commands; Quad I/O requires the host to drive the four data lines bidirectionally. QPI mode is entered via a command after power-up and locks the interface into quad-only operation until the next reset. For in-system programming, a bootloader on the host MCU can write the flash through the SPI peripheral. For off-board programming, a universal SPI NOR programmer with support for the FL-L series and the 8-SOIC footprint is needed. The 128 Mbit density (16 MB) is typical for firmware images, configuration tables, and data logging in embedded systems.