The R5F100ED is the 48 KB member of the 40-pin row: 6 by 6 mm HWQFN, 3 KB of
RAM, the 4 KB data flash and nine converter channels. It combines the
intermediate memory class with the largest pin count that class reaches in
the family, which is the combination motor-control and compressor boards
tend to choose, and it carries the 48 KB class’s signature FF300H self-RAM
window into a package with plenty of fixture clearance.

FF300H and the 3 KB budget

Volatile memory on the 48 KB class sits from FF300H to FFEFFH, and the
flash library claims the top of it for self-programming. A linker map
showing that reservation proves the image updates itself and says
precisely where the library lives. For readout work the same map fixes
the loader’s home underneath, with enough room for a streaming routine
that keeps the UART busy while the sequencer idles.

Forty-eight blocks with the swap in use

Forty-eight erase blocks carry the program, with the boot region in the
lowest four and its mirror from 02000H. At 48 KB the mirror costs a
twelfth of the array, and field-updated boards pay it gladly: both
copies are usually populated, the duplicated security bytes at 010C0H
and 010C4H swap as a set, and the flag in the first block names the live
generation. A complete capture takes both copies and the flag.

The four-byte word and the interrupted write

Code flash writes four-byte words between block-level erase and verify
cycles, and an update that lost power leaves a half-converted word where
it stopped. On a board that arrives dead, that signature
separates a failed field update from a hardware fault before any deeper
work, and the two diagnoses lead to different jobs: completing the
update is a repair, while a hardware fault goes to the chip reverse engineering service
examination flow.

Nine channels and the compressor loop

The converter’s nine inputs carry the sensing that compressor and motor
boards need, including the current-shunt inputs the control law watches.
Calibration sits in the 4 KB data flash while thresholds live in code,
and a controller cloned without its calibration regulates poorly or not
at all.
The data array’s wear-levelled history also reconstructs the unit’s service
life, which is evidence rather than decoration in most disputes. A
capture that pairs the code with the array therefore reconstructs not
only how the board regulates but how hard it was driven, which is often
the answer the customer actually needs.

Access and protection

Access options follow the package: routed test pads first, then a
fixture, then lift-and-reball, with the 0.5 mm wings and bonded pad
setting the limits. Underneath, the shipped state is the family’s usual
one, guard on, debug gated by an erase bit, both identifiers beside the
vectors, and a single passive read of the first block opens every job
here.

Row context

The 40-pin row continues through R5F100EE flash data to R5F100EH firmware decryption. The
Elsewhere the capacity comes in
24-pin and 30-pin leaded packages (R5F1007D locked flash,
R5F100AD code flash extraction), on the 25-ball and 36-ball grids (R5F1008D embedded memory,
R5F100CD firmware decryption) and as the 44-pin LQFP R5F100FD flash heximal, and service entry
points are firmware extraction service and MCU crack service.

Loader sizing below FF300H

The 48 KB class maps its volatile memory from FF300H, and the flash
library reserves the top of the range for self-programming. That leaves
the space below, under a kilobyte of it, for anything a readout wants to
run, and a compact streaming walker fits with margin: a ring buffer, the
serial routines and a block counter. In-circuit capture on a leaded
package with that loader keeps the board’s own application dormant but
its supply and configuration intact, which matters on boards whose
calibration or counters must not be disturbed by the session. The
walker’s own discipline matters as much as its size: it runs with
interrupts it owns, touches no application variable, and leaves the
stack exactly as it found it. On industrial boards where
operating-hours records carry contractual weight, an in-circuit
session that finishes with counters undisturbed is not a courtesy
but a requirement, and the tight loader budget enforces it
naturally.