The R5F100FA opens the 44-pin LQFP row with the smallest memory
configuration: 16 KB of code flash, 2 KB of RAM, the 4 KB data flash, ten
converter channels and forty I/O in a 10 by 10 mm body on a 0.8 mm pitch. It
is a large, leaded, easy-to-touch package carrying the family’s entry
memory, and it is the natural choice for boards with big I/O spreads and
compact control laws, from vending interfaces to white-goods front panels.

Leads at 0.8 mm change the economics of the job

The 0.8 mm pitch of the LQFP is the most fixture-friendly geometry the
family offers, and in-circuit work on this member is the easiest in the
line: the single-wire TOOL0 pad, the UART pair and the supply pins are all
reachable, and production layouts almost always bring them to test points.
Nothing about that accessibility softens the protection, but it shortens the
path to a legitimate readout enormously, and it makes the lifted-part route
trivial when the identifiers demand it.

Sixteen blocks and the shipped protections

The array divides into sixteen one-kilobyte blocks with the boot cluster in
the first four and the swap mirror at 02000H. Block zero holds the vectors,
the four option bytes with the debug gate and its erase-on-failure bit, both
ten-byte identifiers and the boot flag. Block protection ships enabled. On
front-panel boards the swap feature is rare and the mirrored option bytes at
010C0H are usually erased, which the passive read of block 0 shows at once.

Ten channels, the row’s signature

The 44-pin row carries ten converter channels, two more than the 40-pin
class, and on this member they serve sensor front ends that a 16 KB control
law can still process: temperature points, a supply divider, a
mains-synchronous pair. Calibration lives in the 4 KB data flash with the
wear-levelled logs, and recovering the array alongside the code is what
makes a cloned board regulate like the original rather than merely execute.

The 2 KB budget

With 2 KB of volatile memory the flash library stays ROM-resident, halting
the application during any erase or write. Field updates on this member are
short and surgical, and they leave the option block’s modification state and
a data-flash counter as their trace. Readout needs no library and no RAM
worth mentioning, so in-circuit capture is straightforward: the sequencer’s
idle time serves the read path while the application runs.

The identifiers in practice

The ten-byte debug ID at 000C4H to 000CDH and the ten-byte serial ID at
000CEH to 000D7H are independent, and front-panel boards frequently show the
asymmetry of a populated serial ID with an open debug side, or the reverse.
The passive read of block 0 resolves both states and the 000C3H erase bit
before any tool connects, and that read is the opening move of every job on
every member of the family.

Row context

The 44-pin members with more memory are in R5F100FC locked flash through
R5F100FL firmware decryption. The 16 KB die in other packages is the 20-pin
R5F1006A flash memory, the 24-pin R5F1007A memory readout, the 30-pin R5F100AA flash data, the
32-pin R5F100BA locked flash, the 36-ball R5F100CA flash memory, the 40-pin
R5F100EA program memory and the 48-pin R5F100GA memory readout. The general service entry
points are the microcontroller unlock service and firmware extraction service pages.

The ten by ten LQFP as a workbench part

With 0.8 mm lead pitch on a 10 by 10 mm body, this is the friendliest
package the family offers. Every lead is individually reachable, a
general-purpose fixture lands on it without adapters, and a lifted part
can be re-soldered by hand rather than re-balled. Ten converter inputs,
forty I/O lines and seven external interrupts make it the natural
platform for boards that were designed to be serviced. The security
architecture is exactly as closed as anywhere else, but the mechanics of
every step, from the first passive read of block zero to the final
verification pass, are measurably simpler than on any smaller body. Session economics
follow the package: a capture, a verification pass and even a
write-back fit comfortably into a single visit, which is one reason
this footprint dominates the service side of the family’s history.