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decrypt embedded microcontroller eeprom memory, as we mentioned above, embedded microcontroller decrypter can use laser scanning to read the status of transistors. And just embedded microcontroller decrypter expected, laser can scan the P and N type transistor’s source in the embedded microcontroller memorizer as well as the photocurrent generated from the drain electrode, un-transparent metal wire can be use to treat the lowest photocurrent.
The result of laser scanning can see the photocurrent in the inverse switch status of SRAM unit obviously whembedded microcontrollerh can be used to assure the embedded microcontroller memorizer status after decrypting it. In order to explain the result for the purpose of pursuit more proper scanning parameters, use DIODE-2D present the laser impulse to two dimension of reversor after Decrypt Embedded Microcontroller Eeprom Memory.

The length of narrow channel is assumed to be 1 micron, laser radiation strength is 1.104W/cm2. Other parameters, such as mixed density, P and N channel depth, use the standard 1 micron N type base CMOS technology parameter of embedded microcontroller.

Embedded microcontroller decrypter has simulate the two status of reversor, the laser with different wavelength on the various locations, their relationship with the power supply current can reveal that the current of transistor in the turn off exposure status could be much bigger than the current in the turn on exposure status when Decrypt Embedded Microcontroller Eeprom Memory. Turn up the shutdown transistor channel can increase the total current and its increasing amount is much bigger than the slightly decrease the open channel resistor slight.

clone microprocessor flash memory is a prevail technology in the industry of Electronic Product Reverse Engineering, Relevant protection mechanism has been established to protect microprocessor flash memory clone in the world. Asynchronous logic is a recently developed clone microprocessor flash memory protection technology, it has been introduced after the synchronous dual line logic promotion.

As we all know, traditional digital logic use only one clock to synchronize the operation. But accompany with acceleration of clock rate, this synchronized operation becomes more and more complicate. Due to this reason, it give rise to the self-synchronized or asynchronous design without the clock.

There is one way is to use random technology on the data line to prevent clone microprocessor flash memory, in the dual line logic, signal zero and one is not high and low electrical press on single line anymore, but a pair of signal combination on the line. Such as zero could probably LH, while one is probably HL, when in the application of synchronous circuit, LL signal means motionless.

The main drawback of all these simple arrangement is they are very fragile: un-wanted HH status could emerge due to the circuit disadvantage when clone microprocessor flash memory.

Self-asynchronous design can be used to fend off the clock noise microprocessor flash memory cloneing. If the serial interface need clock, it is relatively easier to separate the clock from sensitive circuit. Power supply noise microprocessor flash memory clone can seldom work on the asynchronous circuit, however, for those microprocessor flash memory with eeprom as memorizer won’t be protected and could be cloned.

Dual Line design can obtain the alerting signals from sensor modification reliably, and constrain the operation of microprocessor flash memory. The final result could be the deletion of sensitive data from microprocessor flash memory and trigger the alert, it can prevent the flaw injection microprocessor flash memory clone to gain success, microprocessor flash memory cloneer should inject two failure status simultaneously and make the status of transmitting line from LH switch to HL, which can cause the transmitting status enter into HH immediately and trigger the alert right away.

We can hack microchip processor TSC87C51 locked programe, please view the microchip processor TSC87C51 features for your reference:
TEMIC’s TSC87C51 is high performance CMOS EPROM version of the 80C51 CMOS single chip 8 bit microchip processor.
The fully static design of the TSC87C51 allows to reduce system power consumption by bringing the clock frequency down to any value, even DC, without loss of data.

The TSC87C51 retains all the features of the 80C51 with some enhancement: 4 K bytes of internal code memory (EPROM); 128 bytes of internal data memory (RAM); 32 I/O lines; two 16 bit timers; a 5-source, 2-level interrupt structure; a full duplex serial port with framing error detection; a power off flag; and an on-chip oscillator.
The TSC87C51 has 2 locked programe-selectable modes of reduced activity for further reduction in power consumption. In the idle mode the CPU is frozen while the RAM, the timers, the serial port and the interrupt system continue to function. In the power down mode the RAM is saved and all other functions are inoperative.
The TSC87C51 is manufactured using non volatile SCMOS process which allows it to run up to after hack microchip processor TSC87C51 locked programe:
33 MHz with VCC = 5 V ± 10%.
16 MHz with 2.7 V < VCC < 5.5 V.
4 Kbytes of EPROM
G Improved Quick Pulse programming algorithm
G Secret ROM by encryption
128 bytes of RAM
64 Kbytes program memory space
64 Kbytes data memory space
32 programmable I/O lines
Two 16 bit timer/counters
Programmable serial port with framing error detection
Power control modes
Two–level interrupt priority
Fully static design
0.8µ SCMOS non volatile process
ONCE Mode
Enhanced Hooks system for emulation purpose
Available temperature ranges:
G commercial
G industrial
Available packages:
PDIP40 (OTP)
PLCC44 (OTP)
PQFP44 (OTP) before hack microchip processor TSC87C51 locked programe
CQPJ44 (UV erasable)
CERDIP40 (UV erasable)
Port 2 is an 8 bit bi-directional I/O port with internal pullups. Port 2 pins that have 1’s written to them are pulled high by the internal pullups, and in that state can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL, in the DC parameters section) because of the internal pullups.
Port 2 emits the high-order address byte during fetches from external Program Memory and during accesses to external Data Memory that use 16 bit addresses (MOVX @DPTR). In this application, it uses strong internal pullups when emitting 1’s. During accesses to external Data Memory that use 8 bit addresses (MOVX @Ri), Port 2 emits the contents of the P2 Special Function Register after hack microchip processor TSC87C51 locked programe.
Port 2 can sink/source three LS TTL inputs. It can drive CMOS inputs without external pullups. Some Port 2 pins receive the high–order address bits and control signals during EPROM programming and program verification if BREAK IC.

Most locked devices say nothing about themselves. This one is different, because it has a USB port, and a USB device cannot be anonymous. Before any application code runs in a meaningful sense, the product has already told the host what it is, what class it belongs to, how many endpoints it has, and what each of them is for.

That handshake is a genuine head start on a replication job, and it is also the source of a persistent misunderstanding. Teams capture the descriptors, conclude that they have the device, and discover later that they have only its business card.

What the host learns without asking permission

On connection the device is enumerated: the host resets it, reads the device descriptor, assigns an address, then reads the configuration, interface and endpoint descriptors, and finally requests the string descriptors that carry the manufacturer and product names.

All of that is plaintext on the bus, and all of it can be recorded with a passive capture. What it establishes:

The last row is worth attention. Products that derive a serial number from a unique identifier or from flash content produce a string with a recognisable structure, and seeing that structure is often enough to establish that the firmware reads something per-unit at start-up.

What the descriptors do not tell you

They do not tell you what any of the vendor-specific requests do, and on a device that is not implementing a standard class, that is the entire protocol.

They also do not tell you the meaning of the data in either direction. A report of sixty-four bytes is sixty-four bytes; whether the first two are a setpoint and the next two a measurement, or the other way round, is decided by code that lives in the array.

They do not tell you the endpoint behaviour under load: whether double buffering is used, whether the transfer is interrupted mid-packet, whether an error causes a stall or a retry. That is all configured in the controller registers from constants in flash.

What descriptors do give you is a skeleton to hang the recovered code on. When the image is available, the descriptor block appears in it as a byte table — usually early in the code section, in the same order the host read it. Matching the captured descriptors against the byte table locates the table, and the code that references that address is the code that handles enumeration.

The identifier trap

A replicated device that behaves identically but presents a different vendor or product identifier will not load the same driver on the host. Operating systems bind drivers to that pair, and a clone with a new identifier is a different product to the operating system even though it is the same board.

If the replication is intended for internal repair or for a second source of the same product, the identifiers must be preserved, which is legally a different proposition from copying them. If it is intended as a new product, the identifiers must be changed, and then the host-side software has to be changed with them.

Establishing which case applies is a commercial question, and it is worth asking before any work begins. It changes the deliverable from an exact image to a modified one, and it changes what the customer can legally do with it.

There is no USB bootloader here

A reasonable assumption on a part with a USB port is that firmware can be updated over that port by default. On this family it cannot: the factory loader lives in flash and speaks a UART protocol, not USB. There is no ROM-resident USB loader to fall back on.

The consequence for a locked device is direct. The USB port is an interface to the application, not to the boot loader, so a device that has stopped enumerating cannot be recovered through that port. Recovery goes through the UART loader described in LPC2102FBD48 data recovery, or through the debug port, or through the package.

That distinction catches people who are used to later generations of parts where a USB boot mode exists, and it is worth stating plainly in any quotation.

Where the memory budget lands

Thirty-two kilobytes of flash and eight kilobytes of SRAM is a tight budget for a USB product. The controller itself needs buffer space, the descriptors take a few hundred bytes, and the application has to do something useful with what remains.

Practically, this means the firmware does not contain a USB stack so much as a hand-rolled subset of one. That is good news for reading it: a hand-written implementation is compact and its state machine is visible in the code, where a vendor stack would be an opaque library with a documented API. The recovered image frequently reads like a description of the protocol written in C.

The replication checklist

• captured descriptors, transcribed exactly
• vendor-specific request codes, recovered from the code that dispatches them
• endpoint buffer configuration, recovered from the controller initialisation
• the string descriptors, including the format of any serial number
• the whole array, trimmed, with the reserved region excluded
• clock and bus configuration, since USB timing depends on both

Six items, and the last two are the ones that are forgotten. A replicated USB device with a slightly wrong bus clock enumerates intermittently, which is the worst possible failure mode: it works on the bench and fails at the customer site.

A closing note on layered identity

A USB product has three identities: what it announces, what it does, and how it does it. Capture gives you the first in a minute, the recovered image gives you the third, and the second is the work.

The other end of the family, where the array is large enough to carry a full protocol stack rather than a hand-rolled one, is covered in LPC2138FBD64 locked flash work. What travels with an image besides the code is set out in LPC2134FBD64 firmware extraction, and the clock dependency that governs USB timing is treated in LPC2136FBD64 duplication.

We can break encrypted microprocessor TS83C51U2 eeprom content, please view the encrypted microprocessor TS83C51U2 features for your reference:
Some instructions operate internally as read followed by write operations. The BCF and BSF instructions, for example, read the entire port into the CPU, execute the bit operation and rewrite the result.
Caution must be used when these instructions are applied to a port where one or more pins are used as input/outputs. For example, a BSF operation on bit 2 of GPIO will cause all eight bits of GPIO to be read into the CPU, bit 2 to be set and the GPIO value to be written to the output latches.
If another bit of GPIO is used as a bidirectional I/O pin (say bit 0), and it is defined as an input at this time, the input signal present on the pin itself would be read into the CPU and rewritten to the data latch of this particular pin, overwriting the previous content before Break Encrypted Microprocessor TS83C51U2 Eeprom Content.
As long as the pin stays in the Input mode, no problem occurs. However, if bit 0 is switched into Output mode later on, the content of the data latch may now be unknown.
Example 5-1 shows the effect of two sequential Read-Modify-Write instructions (e.g., BCF, BSF, etc.) on an I/O port.
A pin actively outputting a high or a low should not be driven from external devices at the same time in order to change the level on this pin (“wired OR”, “wired AND”). The resulting high output currents may damage the chip.
The actual write to an I/O port happens at the end of an instruction cycle, whereas for reading, the data must be valid at the beginning of the instruction cycle (Figure 5-2) if Break Encrypted Microprocessor TS83C51U2 Eeprom Content.
Therefore, care must be exercised if a write followed by a read operation is carried out on the same I/O port. The sequence of instructions should allow the pin voltage to stabilize (load dependent) before the next instruction causes that file to be read into the CPU.
Otherwise, the previous state of that pin may be read into the CPU rather than the new state. When in doubt, it is better to separate these instructions with a NOP or another instruction not accessing this I/O port.
The Timer0 module has the following features:
8-bit timer/counter register, TMR0
Readable and writable
8-bit software programmable prescaler
Internal or external clock select:
– Edge select for external clock when Break Encrypted Microprocessor TS83C51U2 Eeprom Content
Figure 6-1 is a simplified block diagram of the Timer0 module.
Timer mode is selected by clearing the T0CS bit (OPTION<5>). In Timer mode, the Timer0 module will increment every instruction cycle (without prescaler).
If TMR0 register is written, the increment is inhibited for the following two cycles (Figure 6-2 and Figure 6-3). The user can work around this by writing an adjusted value to the TMR0 register.

We can reverse engineering microchip processor TS80C54X2 flash code, please view the microchip processor TS80C54X2 features for your reference:
The Timer0 module has the following features:
8-bit timer/counter register, TMR0 Readable and writable
8-bit software programmable prescaler Internal or external clock select:
– Edge select for external clock
– External clock from either the T0CKI pin or from the output of the comparator
Figure 7-1 is a simplified block diagram of the Timer0 module.
Timer mode is selected by clearing the T0CS bit (OPTION<5>). In Timer mode, the Timer0 module will increment every instruction cycle (without prescaler) after Reverse Engineering Microchip Processor TS80C54X2 Flash Code.
If TMR0 register is written, the increment is inhibited for the following two cycles (Figure 7-2 and Figure 7-3).
The user can work around this by writing an adjusted value to the TMR0 register.
There are two types of Counter mode. The first Counter mode uses the T0CKI pin to increment Timer0. It is selected by setting the T0CS bit (OPTION<5>), setting the CMPT0CS bit (CMCON0<4>) and setting the COUTEN bit (CMCON0<6>).
In this mode, Timer0 will increment either on every rising or falling edge of pin T0CKI. The T0SE bit (OPTION<4>) determines the source edge.
Clearing the T0SE bit selects the rising edge. Restrictions on the external clock input are discussed in detail in Section 7.1 “Using Timer0 with an External Clock (TS80C54X2)”.
The second Counter mode uses the output of the comparator to increment Timer0. It can be entered in two different ways. The first way is selected by setting the T0CS bit (OPTION<5>) and clearing the CMPT0CS bit (CMCON<4>) before Reverse Engineering Microchip Processor TS80C54X2 Flash Code;
(COUTEN [CMCON<6>]) does not affect this mode of operation. This enables an internal connection between the comparator and the Timer0.
The second way is selected by setting the T0CS bit (OPTION<5>), setting the CMPT0CS bit (CMCON0<4>) and clearing the COUTEN bit (CMCON0<6>).
This allows the output of the comparator onto the T0CKI pin, while keeping the T0CKI input active. Therefore, any comparator change on the COUT pin is fed back into the T0CKI input. The T0SE bit (OPTION<4>) determines the source edge before Reverse Engineering Microchip Processor TS80C54X2 Flash Code.
Clearing the T0SE bit selects the rising edge. Restrictions on the external clock input as discussed in Section 7.1 “Using Timer0 with an External Clock (TS80C54X2)”

The largest member of this branch is also the one where a customer is most likely to assume the worst. Half a megabyte of flash sounds like a large amount of intellectual property, and a locked device sounds like a large amount of it lost.

Neither assumption survives contact with the sector map. What matters at this density is not how much is stored but how the array is divided, because the division determines what a failure costs and what a partial recovery can still deliver.

The map, and why the first sector is still the only one that matters

The array is built from two sizes of block: a group of small sectors at the bottom and a run of large ones above them. The small ones exist so that the vector table and the protection word can be erased as a unit without destroying the application, and the large ones exist so that a big image can be erased quickly.

Everything about protection is decided by the small end. The control word sits at the end of the first sector, the vector table sits at the start of it, and the boot loader’s decision to run the application or wait for a command is made by reading four bytes inside it.

That last row is more dangerous at this density than at any other, because a full read of half a megabyte is exactly the kind of file somebody writes back without inspecting. The reserved region is not part of the product and writing over it costs the device its programming interface.

What a lock at this density actually protects

The same control word, with the same three values, producing the same four states described in LPC2101FBD48 protection states. Nothing about the mechanism scales with density.

What scales is the amount of code behind it, and that changes the commercial picture rather than the technical one. A half-megabyte image is unlikely to be entirely hand-written application logic; it usually contains a protocol stack, a file system, a display font set, or a table of measured calibration data. Those components have different values to different customers, and knowing which one is present shapes the recommendation.

A product whose array is mostly a font table is a product whose secret is small. A product whose array is mostly a protocol stack is a product whose secret is licensed from somebody else, and the customer may not have the right to have it recovered at all. Establishing which is which before quoting is part of the job.

Reading time changes the procedure

Half a megabyte through a serial port at a modest rate is not instantaneous, and the practical consequence is that a read should be done in one session rather than resumed across power cycles. A device that is power-cycled mid-read may return to the application, and the next sync has to start over.

Through the debug port the read is faster, and there the constraint is different: a long halt on a running product may trip a watchdog. On a device of this size the firmware is more likely to have one.

Neither issue is a problem in itself. Both become problems when the operator is not expecting them and starts improvising in the middle of a capture.

Partial recovery is where this density pays

With eight small sectors and a run of large ones, the loss of a single large sector still leaves most of the image. That is not true at the bottom of the family, where a lost sector is a lost eighth.

Two practical uses follow.

The first is targeted work. A customer who needs the calibration tables knows roughly where they are, usually in the upper half. Reading only the sectors that hold them is quicker, and it produces a smaller artefact with a clear boundary.

The second is salvage. A device with a failing sector at high addresses can still yield a coherent application if the damage is confined to data rather than code. Reporting which sectors are verified, which are reconstructed and which are missing, in the three-level form described in LPC2132FBD64 data recovery, is the difference between a useful salvage and a file nobody dares to use.

The parameter store at this size

Larger arrays tend to carry a larger settings block, and the top of the array very often holds it. On this device the store is still an emulated log built from erased sectors, and it is still the cheapest thing to recover and frequently the most valuable.

The structure is the same one described in LPC2119FBD64 parameter store work: records with markers and sequence numbers, compacted between sectors as they fill. At this density there is more room for history, which is good news, because a compaction that happened months ago may still leave the previous copy of every record intact in the sector that was not yet erased.

Looking for those older copies is a routine step, and it is the reason a device whose current settings are corrupt can still be restored.

When the array does not answer

Then the options narrow to the ones in LPC2104FBD48 erase behaviour, and the headline is unchanged at every density: the only route that clears the protection also clears the content, and the only route that preserves content does not go through the protection at all.

The difference at half a megabyte is the size of the loss, and the conversation with the customer should be proportionally more careful. Losing eight kilobytes of control loop is one thing. Losing a stack, a font set and three years of measured calibration is another, and the decision deserves to be made deliberately rather than in the middle of a procedure.

A short summary of the trade

The first eight kilobytes decide whether you can work at all. The rest decides how much of the product you can describe. On the largest part in the family those two facts are separated by four hundred and ninety-six kilobytes of distance, which is exactly why the small end deserves all of the caution and the large end deserves all of the patience.

A duplicate that runs is not the same thing as a duplicate that behaves. The difference is almost always the clock, and on this family the clock is a small block of registers set by the first fifty instructions of the firmware.

Copying flash is a solved problem once the array is readable. Reproducing the timing environment the flash expects is the part that determines whether the resulting board meets its specification or merely boots.

What the clock chain looks like

The device can run from an external crystal through a phase-locked loop, or directly from the crystal, or from an internal oscillator depending on the variant. The interesting case is the loop, because that is what production firmware uses.

The loop multiplies the oscillator up to an internal frequency and divides it back down to the core clock. The multiplier and divider are set as two fields in one register: a multiplier, and a divider restricted to a small set of powers of two. The settings are then committed with a fixed two-byte sequence written to a feed register, because an accidental write to a clock register is a good way to stop a device permanently.

Below the core clock sits a second divider that sets the peripheral bus. On this family it can be the core clock, half of it, or a quarter. Every peripheral timing reference — baud rate, timer tick, CAN bit, ADC conversion — is computed against that bus clock, not against the core.

Why a byte copy fails on a different board

Three failure modes account for almost every case.

The first is a different crystal. A board built with a 12 MHz part and a board built with a 14.7456 MHz part produce different core clocks from the same register values, and every derived timing shifts by the same ratio. The UART baud rate lands on a value the other end does not recognise; the product appears dead on its service port.

The second is the same crystal with a different loop setting. This happens when a product was cost-reduced: the firmware was rebuilt for a slower core to save power, and a copy of the older image runs the new board too fast, which shows up as marginal flash access rather than as an obvious fault.

The third is the peripheral divider. Changing it changes all peripherals at once, which is why a board that boots and communicates but cannot measure accurately is nearly always a divider mismatch rather than an analog problem.

Reading the configuration out of the image

The clock setup is the first thing the reset code does, before memory is initialised and before any peripheral is touched, which makes it easy to find. Look for writes to the clock block near the base of the array, immediately after the stack pointer is set.

Extract the multiplier and divider, compute the resulting core frequency against the crystal the board actually has, and compare it against the frequency the rest of the firmware assumes. The rest of the firmware states its assumption implicitly, in the constants loaded into baud rate divisors and timer reload registers, so the two can be checked against each other.

When they agree, the image was built for this board and the duplicate will behave. When they disagree, the image came from a different board revision, and that is a finding worth reporting before anything is written to a replacement.

Reworking instead of matching

Sometimes the crystal on the new board cannot be changed. In that case the image has to be reworked, and the work is mechanical but wide: recompute every baud divisor, every timer reload, every CAN bit timing, every delay loop.

Software delays are the ones that bite. A loop written as a fixed count of iterations has its timing baked into the instruction stream, and no register adjustment fixes it. Products with bit-banged protocols or charge-pump sequencing often contain such loops, and a duplicate that runs ten percent fast can fail in ways that look mechanical.

Protected devices change the order of work

Where the device is protected, the configuration cannot be read out through a port, and the sequence becomes: establish access first, then read, then analyse the clock, then decide. The access question is covered in LPC2101FBD48 protection states, and the read itself in LPC2102FBD48 data recovery.

What must not happen is a duplicate produced from a partial understanding: image copied, clock assumed, board shipped. The failure appears weeks later as an intermittent fault in the field, and by then the connection between cause and effect is lost.

Deliverable

A duplication job should hand over four things: the image, the clock configuration as extracted, the derived frequencies for the board the image came from, and a statement of what must match on the replacement board. That fourth item is the one that prevents the second job, and it costs a paragraph.

The wider reading of what else travels with an image — interrupt structure, parameter blocks, network identity — is in LPC2134FBD64 firmware extraction and LPC2129FBD64 firmware recovery. For the arithmetic of a partial image, LPC2132FBD64 data recovery covers what to do when part of the array is missing.

The short version

Copy the flash. Then prove the clock. A duplicate that has been checked against its timing assumptions is a product. A duplicate that has only been verified byte for byte is a hope.

We can read atmel IC ATMEGA16A locked code, please view the atmel IC ATMEGA16A features for your reference:
The atmel IC ATMEGA16A devices incorporate an on-chip Power-on Reset (POR) circuitry, which provides an internal chip Reset for most power-up situations.
The on-chip POR circuit holds the chip in Reset until VDD has reached a high enough level for proper operation. To take advantage of the internal POR, program the GP3/MCLR/VPP pin as MCLR and tie through a resistor to VDD, or program the pin as GP3.
An internal weak pull-up resistor is implemented using a transistor (refer to Table 12-2 for the pull-up resistor ranges). This will eliminate external RC components usually needed to create a Power-on Reset. A maximum rise time for VDD is specified.
See Section 12.0 “Electrical Characteristics” for details. When the devices start normal operation (exit the Reset condition), device operating parameters (voltage, frequency, temperature,…) must be met to ensure operation after Read Atmel IC ATmega16A Locked Code.
If these conditions are not met, the devices must be held in Reset until the operating parameters are met. A simplified block diagram of the on-chip Power-on Reset circuit. The Power-on Reset circuit and the Device Reset Timer (see Section 9.5 “Device Reset Timer (DRT)”) circuit are closely related. On power-up, the Reset latch is set and the DRT is reset. The DRT timer begins counting once it detects MCLR to be high.
After the time-out period, which is typically 18 ms, it will reset the Reset latch and thus end the on-chip Reset signal. A power-up example where MCLR is held low is shown in Figure 9-3. VDD is allowed to rise and stabilize before bringing MCLR high.
The chip will actually come out of Reset TDRT msec after MCLR goes high. In Figure 9-4, the on-chip Power-on Reset feature is being used (MCLR and VDD are tied together or the pin is programmed to be GP3) when Read Atmel IC ATmega16A Locked Code.
The VDD is stable before the Start-up Timer times out and there is no problem in getting a proper Reset. However, Figure 9-5 depicts a problem situation where VDD rises too slowly. The time between when the DRT senses that MCLR is high and when MCLR and VDD actually reach their full value, is too long. In this situation, when the Start-up Timer times out, VDD has not reached the VDD (min) value and the chip may not function correctly. For such situations, we recommend that external RC circuits be used to achieve longer POR delay times if RECOVER MCU.

Extraction is often quoted as if the deliverable were a file. Customers who have received a file and nothing else tend to come back with a second, harder question: what does it do.

The answer is in the image, and on this family there is a particular structure that makes it easy to read. The interrupt controller is not a simple priority encoder. It is a vectored unit with sixteen slots, each holding the address of a handler, and the firmware populates those slots at start-up. Enumerating them produces an outline of the product in about twenty minutes.

How the controller is organised

The unit sits at a fixed address above the peripheral space and presents a small register file: an interrupt selector, an enable register, a set of sixteen vector address registers, a default vector address, and a register that reports which handler is currently being serviced.

The mechanism is straightforward. A peripheral raises a request; the controller picks the highest-priority enabled source; it reads the address from the corresponding slot and jumps there. The handler does its work, writes to the read-back register to signal completion, and returns. If no slot is programmed, the default handler runs, which on most firmware is a loop that logs and resets.

Two properties of that design are useful during analysis:

• every handler has an entry in the slot table, so the table is a complete list of what the firmware responds to
• the slot table is written once, early, from constants, so it survives in the image as a small block of addresses

Reading the table

The initialisation sequence writes a constant to each slot it cares about. In a disassembly those writes appear as a run of address constants loaded into a register and stored to consecutive addresses. Extracting them gives a list of handler entry points, and the index in the list is the source number.

The indices are the interesting part. A product that programs slots for the UART, the timer and one external interrupt is a product that does three things. A product that programs eleven slots is doing something much more elaborate, and the extra entries usually describe which peripherals matter — the ADC, the PWM block, the watchdog, the real-time clock, the two serial ports.

The fast interrupt is its own story

The fast interrupt input bypasses the vector unit entirely. It has one address, no priority, and it runs in a mode with its own registers. Firmware uses it for exactly one purpose: a task that cannot tolerate the latency of the vectored path.

When the recovered image programs the fast interrupt vector to something other than a stub, that one fact reorders the priorities of the whole investigation. It means the product has a timing requirement strict enough to justify the complexity, and the handler is where the reason will be found — a shaft encoder, a current loop, a bit-banged protocol, or a watchdog refresh that must not be delayed.

Turning the map into a document

Once the handlers are located, each one can be characterised by what it touches. A handler that reads a data register and writes it to a buffer is a receive path. One that loads a compare register from a table is a waveform generator. One that increments a counter and compares it against a constant is a scheduler tick.

That characterisation, assembled across the sixteen slots, is a description of the product’s real-time structure, and it is the part of the deliverable a customer can check against their own knowledge. Names are lost, but function is not.

Where the map comes from in the data

Two places in a stripped image carry the same information, and either can be used when the other is missing.

The initialisation code writes the slot table, which gives the intended mapping. The handlers themselves end with a write to the read-back register, which confirms the mapping from the other side: a routine that writes the completion register is a handler, regardless of where the table says it belongs.

Cross-checking the two catches the case where a handler was replaced at run time — a diagnostic mode, a firmware update path, a safety fallback. Those replacements are real behaviour and are worth reporting separately.

Why this matters commercially

A customer who needs to maintain an orphaned product does not need the source. They need to know which interrupts exist, what each one does, and how the work is scheduled. That is a maintenance document, and it can be produced from a locked device the moment the array is readable.

The same method applies upward and downward in the family. LPC2114FBD64 code reading covers the instruction-level side, including the constant pools where peripheral addresses hide, and LPC2131FBD64 heximal work shows what the same structure looks like when the budget was too tight for sixteen handlers. On a Cortex-M part the same analysis is easier because the vector table is in memory rather than in a peripheral — see STM32F103CB recovery for the contrast.

A short procedure

Read the image, find the peripheral block containing the controller, locate the initialisation writes, extract sixteen addresses, and disassemble from each. Expect an hour for the first pass and a day for the characterisation, and expect the resulting document to answer questions that the customer did not know how to ask.

That document, not the binary, is what makes the extraction worth commissioning.