R5F100CC pairs 32 KB of code flash with the 4 by 4 mm 36-ball wafer-level
package, keeping the 2 KB RAM, 4 KB data flash and eight converter channels
of the small-memory row. The 36-pin members are the first in the family to
carry two serial channels with the simplified I2C doubled alongside, and at
this capacity the protocol stacks that justify those peripherals fit
comfortably. The bench-facing facts are the ball-grid package and the
family-standard protection inside it.

Two serial channels and what they carry

The serial array on this row is one UART with LIN support, two clocked
serial interfaces and two simplified I2C units, plus a hardware I2C bus. The
distinction matters in recovery because the field update path typically runs
on one specific channel, and the image’s interrupt structure shows which.
The same structure tells whether the update protocol is the manufacturer’s
bootloader conversation or a custom one, and that decides what a readout
session has to emulate if the capture is to happen in circuit.

Thirty-two blocks, one configuration block

The array divides into thirty-two one-kilobyte blocks, four of which form the
boot cluster with its mirror at 02000H. Block zero carries the vectors, the
four option bytes, both ten-byte identifiers and the boot flag; block
protection ships enabled. The four-byte programming word means any patch is
word-aligned and any interrupted write leaves the mixed-word signature at
the exact boundary the updater reached. On a 32 KB image that signature is
usually easy to find and always informative.

The identifiers under the balls

The ten-byte debug ID at 000C4H to 000CDH and the ten-byte serial ID at
000CEH to 000D7H are independent, and the 000C3H byte decides whether the
debug path erases on failure. On consumer boards built on this member, one
identifier is often blank: either the factory programmer path was left open
or the debug side was never closed. The passive read of block 0, which needs
no authentication at all, establishes both states before any tool connects,
and that read is possible through a single good ball if the layout gives
even that much.

Reading through a fixture

A 4 by 4 mm ball grid at 0.5 mm pitch is well within the reach of a sprung
pin fixture, and boards with ground floods around the footprint usually leave
enough clearance for one. Where they do not, the lift-and-reball route onto
an adapter gives a clean capture platform, and the part returns to service
afterwards. The die itself, when the image must be recovered below the
package level, is the IC decapsulation service service’s domain, and package-level
examination is part of the chip reverse engineering service flow.

The data flash and the protocol evidence

The 4 KB data flash holds calibration and logs, and on protocol-heavy images
it also holds session counters and pairing data for the communication stack.
Those records are part of the board’s identity: a cloned controller without
them pairs like a stranger. Capturing the array alongside the code is
therefore standard, and the wear-levelled structure of the records dates the
unit’s history.

Row context

The 36-pin siblings are in R5F100CA flash memory and R5F100CD firmware decryption through
R5F100CG flash heximal. The 32 KB die in leaded packages is the 20-pin
R5F1006C code flash extraction and the 30-pin R5F100AC flash memory; in the 32-pin QFN it is
R5F100BC flash heximal. Architecture comparisons with a previous generation whose
serial protection was a single lock bit are in MC9S08QD4 memory read, and the general
family workflow is the MCU crack service page.

The reset ladder from power-on down

Three mechanisms stand between a rising supply and running code, and each
one is configurable from the option area. The power-on release circuit
holds everything until the rail is physically valid, the programmable
detector adds a threshold chosen by the author, and the watchdog, windowed
or plain, takes over once execution starts. A board that resets in a
pattern matching none of these is telling the analyst something about its
periphery rather than its program store, and separating supply-behaviour
faults from image faults at the outset saves hours on boards that arrive
with vague symptoms. The same ladder runs on every member of the
line; what differs here is only how much of it the author chose to
configure, and reading that choice is itself evidence.