32-Mbit SPI flash in a 5×6 UDFN
The AT45DB321E-MHF-T is a 32-Mbit serial flash from Renesas, organized as 528 bytes per page across 8192 pages — the non-power-of-two page size is characteristic of the DataFlash family and matters when the firmware layer expects 512-byte sectors; the extra 16 bytes per page are available for ECC or metadata storage without wasting a full sector. It communicates over a standard SPI bus at up to 85 MHz, which translates to a raw read throughput of roughly 10.6 MB/s in single-I/O mode — adequate for code shadowing or configuration storage in a microcontroller-based system where the SPI host runs at that clock rate.
Write timing and page-program strategy
Page program takes 4 ms typical, and the word-write cycle is 8 µs — these are the numbers the firmware scheduler budgets around; a 4 ms write window means the host must either poll the RDY/BUSY status bit or insert a delay loop, and any interrupt that preempts the polling loop risks a partial-page write if the flash has already started the internal erase-before-write cycle. The 528-byte page organization means a 512-byte application sector plus 16 bytes of overhead — the firmware's flash driver must handle the offset calculation when mapping logical sectors to physical pages, or the extra bytes cause a sector-size mismatch that corrupts the filesystem.
Supplied in Tape & Reel (TR) and Cut Tape (CT) options — the TR quantity is the reel count; CT is suitable for prototype or low-volume builds where the full reel is not needed.