256 Mbit NOR Flash for code storage and OTA updates
The S25FL256SDSMFI003: It uses a Quad I/O SPI interface running at 80 MHz, supporting execute-in-place (XIP) boot and over-the-air update staging.
Quad I/O mode uses four data lines for reads and writes, delivering an effective throughput of 320 Mbps at 80 MHz (four bits per clock). That is enough to feed a Cortex-M4 or M7 core running from external flash without stalling on instruction fetches, provided the controller's QSPI peripheral supports the fast-read command set. The 256 Mbit density (32 MB) gives room for a main application image plus a backup for fail-safe OTA; the FL-S family supports 4 KB and 64 KB sector erase granularity, which matters when sizing the staging area and wear-leveling the config blocks.
For the procurement desk, that removes the urgency to stockpile or qualify a drop-in replacement for ongoing production.