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How do you Reverse Engineering a printed circuit board?

How do you Reverse Engineering a printed circuit board


Reverse engineering a printed circuit board (PCB) involves taking an existing PCB and analyzing its components, connectivity, and functions to understand how it works. This allows you to recreate the schematics and gain insight into the PCB’s design. Reverse engineering has many uses across fields like failure analysis, security research, and competitive benchmarking. With the right tools and systematic approach, engineers can reliably reverse engineer PCBs.

Steps for Reverse Engineering a PCB

Here are the key steps involved in reverse engineering a PCB:

1. Visual Inspection

Start by visually inspecting the PCB. Look for:

  • Key components like microcontrollers, memories, power regulators etc.
  • Component markings and part numbers
  • Board markings like version numbers, copyright notices etc.
  • Layer stackup – number of copper layers
  • Construction – through-hole, surface mount, or a mix
  • Signs of modifications or repairs

Make notes on the board’s attributes, shot images for reference, and draw a block diagram of major sections.

2. Salvage Identifiable Components

Identify generic components like resistors, capacitors, diodes, transistors etc. Check online datasheets to determine their specifications. For complex ICs, note down all markings. You’ll research them later. Carefully de-solder and salvage any components that may help the reverse engineering process.

3. Trace the PCB Layout and Connectivity

Now trace the PCB layout and map its connectivity. Follow copper traces between components paying attention to connections like:

  • Power and ground
  • Data and control buses
  • Functional blocks like analog circuits, memory modules, clock circuits etc.

Use a multimeter to trace shorts and opens. Identify test/debug points. Document the connectivity information as you proceed.

4. Research Unidentified Components

For complex ICs with manufacturer part numbers, search online databases to obtain datasheets. For generic chips, look for package type, number of pins etc. Use clues from nearby components and traces. Identify pin functions using the continuity checker. Make your best guess on unclear components and move ahead.

5. Map the Schematics

With the PCB layout connectivity traced and components identified, you can now map out the schematics. Draw the circuit diagram containing all traced connections, with components shown as functional blocks. Identify key sections like microcontroller, peripherals, power supply, UI, connectors etc. Label test points and debug interfaces.

6. Determine Design Functionality

Analyze the mapped schematics to deduce the board’s functionality. Consider factors like:

  • Processor type and peripherals to identify interfaces like USB, Ethernet, UART, SPI etc.
  • Presence of data converters like ADC, DAC for analog I/O
  • Sensors and indicators for user interfaces
  • Current paths and power requirements to determine power supply architecture.

Figure out data flows and component roles to arrive at the functional blocks. Consult programming interfaces like JTAG to gain deeper insights.

Tools for PCB Reverse Engineering

Here are some key tools used for effectively reverse engineering a PCB:

MultimeterTracing connectivity, identifying shorts/opens
OscilloscopeAnalyzing signal activity, debugging interfaces
Logic AnalyzerCapturing digital signal timings and data flows
Bus PirateInterfacing to board programming/debug buses like SPI, I2C
MicroscopeInspecting tiny SMT components and markings
ChemicalsEtching away conformal coatings obscuring traces
X-RaysMapping hidden traces between layers
PCB Design SoftwareDocumenting traced schematics and layouts

Additional specialized tools may be required depending on the specific PCB.


An essential tool for tracing conductivity and checking for shorts and opens. Helps map board connectivity. Advanced meters include continuity tester, transistor checker and other analysis functions.


Oscilloscopes visualize signals over time across board nets and interfaces. Useful for analyzing timing waveforms during debug interfaces like JTAG.

Logic Analyzer

Logic analyzers capture digital signal data flows between components. Useful for understanding data buses. Advanced analyzers can decode interfaces like I2C, SPI based on captured traffic.

Bus Pirate

Small universal chip interface that can emulate interfaces like UART, SPI, I2C. Helps read/write data from unidentified chip peripherals.


Important for inspecting tiny SMT chips and markings unreadable to the naked eye. Also aids in tracing miniature PCB traces.


Ferric chloride, solvents etc used to etch away conformal coatings obscuring P

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