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Archive: September 15, 2023

What is ic decode

What is ic decode

Overview of ic decode

ic decode is a tool used to decode instruction cache (icache) traces from executables. It takes a trace file as input and outputs a human-readable disassembly of the instructions that were executed.

ic decode is useful for analyzing the runtime behavior of programs. By looking at the disassembled icache traces, developers can see exactly which instructions were executed and in what order. This helps with debugging, optimization, and understanding program flow.

How ic decode works

ic decode relies on having an icache trace as input. These traces can be generated by hardware perfomance counters or simulator instrumentation. The trace file contains the memory addresses of instructions executed by the CPU.

ic decode takes this list of addresses and disassembles the corresponding instructions using objdump or a similar disassembler. It matches the addresses to locations in the original executable file.

The output is a disassembly listing showing the instructions in chronological order along with their memory offsets. Additional information like cycle counts or processor core ID can also be included if present in the trace file.

Uses for ic decode

Here are some common uses for ic decode:


By looking at the disassembly, developers can identify hot spots and bottlenecks at a granular instruction level. This helps pinpoint optimization opportunities.

Program analysis

Disassembly provides insight into control flow and data access patterns. This is helpful for understanding program behavior.

Simulation validation

Icache traces from simulators can be compared to traces from real hardware. The disassembly view makes it easy to verify correct execution.

Performance characterization

The number of times each instruction executes can be aggregated. This helps identify optimization targets.

IC Decode Output Format

The output of ic decode consists of:

  • Memory address of instruction
  • Disassembled instruction
  • Cycle count or other optional columns

Here is an example:

0x4000b0add %rbx, %rax10
0x4000b5cmp %rax, %rcx2
0x4000baje 0x12343

The disassembled instructions are shown in order along with the execution metrics. This provides an annotated view of the program trace.

Frequently Asked Questions

How do I generate an icache trace file?

Icache traces can be generated using hardware performance counters or instrumentation in processor simulators. The Linux Perf tool has an --icache option to capture icache profiles. Simulators like gem5 can dump icache accesses.

What information is in an icache trace?

A basic icache trace contains the memory addresses of instructions executed. Additional data like cycle counts, core ids, and processor events can also be included. The trace is a chronological list of icache accesses.

What executables can I use with ic decode?

ic decode relies on having a mapping between instruction addresses and locations in an executable. So it needs the original binary/ELF file used to produce the trace. This allows matching addresses to instructions.

Does ic decode require debug symbols?

No, ic decode does not require separate debug symbol information. It disassembles instructions from the binary file without needing separate debugging files.

How is ic decode different from objdump?

objdump can disassemble an entire executable file. ic decode only disassembles the specific instructions present in the trace file. So it only shows the part of the program that was executed.

Understanding the 7447 IC Decoder

Understanding the 7447 IC Decoder

What is the 7447 IC Decoder?

The 7447 IC is a BCD to 7-segment decoder integrated circuit (IC). It converts binary-coded decimal (BCD) input into a 7-segment display output.

Some key features of the 7447 IC:

  • Decodes 4-bit BCD values into 7-segment outputs
  • Has active-low outputs for driving LED or LCD displays
  • Includes overrides on all outputs for blanking display
  • Available in 16-pin dual in-line package

How Does the 7447 IC Decoder Work?

The 7447 contains internal logic gates that decode the 4-bit BCD input into 7 outputs that can drive an LED or LCD 7-segment display.

Here is the pinout diagram for the 7447:

1-7Segment Outputs (a-g)
8Lamp Test Input
9Blank Input
10-13BCD Inputs (D0-D3)
15+5V Supply
16Overflow Output

The 4 BCD input pins (D0-D3) represent the binary-coded decimal value to be displayed. When a BCD value is applied to these inputs, the 7447 drives the corresponding segment outputs low.

For example, to display ‘5’, the inputs would be 0101. This would drive segments a, f, g, c and d low to form the correct character.

The blank and lamp test inputs can override the BCD inputs and blank or illuminate all segments as needed.

7447 IC Decoder Example Circuit

Here is a simple example circuit using the 7447 to drive a common cathode 7-segment LED display:

This circuit has 4 BCD inputs from toggle switches. The 7447 decodes these inputs and drives the 7-segment display over resistors. A current limiting resistor is used for each LED segment.

7447 IC Applications

The 7447 IC decoder is commonly used in:

  • Digital clocks
  • Electronic meters
  • Calculator and counter displays
  • Scoreboards and other numeric displays

It provides a simple way to decode BCD values from counters, processors or other logic circuits and drive visual numeric displays.

Some other similar decoder ICs are the 7448 (BCD to 7-segment with active high outputs) and 7446/7448 (BCD to 7-segment with open collector outputs).

Frequently Asked Questions

What is the difference between 7447 and 7448 ICs?

The main difference is that the 7447 has active-low outputs while the 7448 has active-high outputs. So the 7447 sinks current when a segment is illuminated while the 7448 sources current.

How much current can the 7447 outputs sink/source?

The standard 7447 and 7448 can sink/source up to 25mA per output pin. Special higher current versions are also available such as the 75447 (75mA drive).

Can a 7447 directly drive an incandescent 7-segment display?

No, an incandescent display requires higher drive current (350mA+) than a 7447 can handle. External transistors or driver ICs are needed to switch enough current for incandescent displays.

Are 7447 ICs still used today?

Yes, the 7447 continues to be a popular and low-cost way to interface simple BCD data sources to numeric LED, LCD and VFD displays. Modern variants are also available with higher drive capacity and other features.

Can a 7447 be cascaded to drive multi-digit displays?

Yes, multiple 7447 ICs can be cascaded to drive larger multi-digit displays. Microcontroller output ports can also digitally multiplex BCD data to multiple 7447s.

Data Sheet for the 74LS138 3-to-8 DecoderDemultiplexer IC

Data Sheet for the 74LS138 3-to-8 Decoder/Demultiplexer IC


The 74LS138 is a 3-to-8 decoder/demultiplexer IC that converts 3 input lines to 8 output lines. It is part of the popular 7400 series logic chip family.

Some key features of the 74LS138 IC include:

  • 3 binary address input lines (A2, A1, A0)
  • 8 active low outputs (Y0 to Y7)
  • Enable input (E1 & E2) to enable/disable all outputs
  • Active low enable mode for full decoding

The 74LS138 can be used for memory addressing, multiplexing, and various other decoding tasks in digital logic circuits.

Pin Configuration

Below is the pin configuration for the 16-pin DIP package of the 74LS138:

Table 1. 74LS138 Pinout Description

1G2AOutput Enable Input
2G2BOutput Enable Input
3G1Output Enable Input
4A0LSB Address Input
5A1Address Input
6A2MSB Address Input
7Y0Active Low Output 0
8Y1Active Low Output 1
9Y2Active Low Output 2
10Y3Active Low Output 3
11Y4Active Low Output 4
12Y5Active Low Output 5
13Y6Active Low Output 6
14Y7Active Low Output 7
16VCCPositive Supply Voltage

Logic Function Table

The following truth table summarizes the logic function of the 74LS138:

Table 2. 74LS138 Logic Function Table

A2A1A0E1E2Active Output
XXX1XDisabled (High Impedance)
XXXX1Disabled (High Impedance)

Typical Applications

  • Memory address decoding – Select 1 out of 8 memory locations
  • Demultiplexing – Route 1 input to 1 of 8 possible outputs
  • Driving indicator LEDs – Light 1 of 8 LEDs based on input
  • Control signals for peripherals – Enable 1 out of 8 devices

Electrical Characteristics

Table 3. 74LS138 Recommended Operating Conditions

VCCSupply Voltage4.755.25V
VIHHigh Level Input Voltage2.0V
VILLow Level Input Voltage0.8V
IOHHigh Level Output Current-0.4mA
IOLLow Level Output Current16mA

Table 4. 74LS138 DC Characteristics

IOHHigh Level Output Current-0.4mA
IOLLow Level Output Current16mA
IIInput Clamp Current-2020μA
ICCSupply Current110mA
Propagation DelayMax (E to Y)2555ns


What is the difference between the 74LS138 and 74HC138?

The main difference is that the 74HC138 uses advanced HCMOS technology making it faster and lower power than the LS TTL based 74LS138. The 74HC138 has higher fan out capability and can operate at lower voltages.

What causes the outputs to go into a high impedance state?

The outputs will enter a high impedance state if either of the enable inputs (E1 or E2) are high. This disables all outputs and makes them float.

How do I select a specific output line?

To select a specific output, the enable pins must be low. Then apply the appropriate 3-bit address to the A2, A1, A0 inputs based on the truth table. The corresponding Y output will go low when selected.

Can I connect the outputs directly to LEDs?

Yes, the 74LS138 outputs are capable of sourcing and sinking enough current to drive most common LEDs directly without any additional components. Add a current limiting resistor in series with each LED.

What is the maximum supply voltage I can use?

Do not exceed the recommended maximum VCC of 5.25V. Higher voltages could damage the IC. It’s best to operate at 5V or less when possible.

HT12D vs HT12E How To Choose The Right EncoderDecoder Chip For Your Project

HT12D vs HT12E: How To Choose The Right Encoder/Decoder Chip For Your Project

The Holtek HT12D and HT12E are popular encoder/decoder chips used in remote control systems. Choosing between these two models can be tricky, as they have similar features but some key differences. This article examines the differences between the HT12D and HT12E to help you pick the right chip.

Overview of HT12D and HT12E

Both the HT12D and HT12E are CMOS LSIs designed for remote control system applications. They use encoders and decoders to transmit and receive data.


The Holtek HT12D is a 12-bit encoder/decoder designed for DC power supply. Key features:

  • Encodes 12-bit data
  • Latchable outputs
  • Low power consumption
  • Operating voltage: 2.4V to 12V DC


The HT12E is also a 12-bit encoder/decoder, with these notable features:

  • Encodes 12-bit data
  • Easy interfacing with microcontrollers
  • Low power consumption
  • Operating voltage: 4.5V to 5.5V DC

Key Differences

While the HT12D and HT12E share similarities, there are some important differences to consider:

Operating Voltage

  • HT12D: 2.4V to 12V DC
  • HT12E: 4.5V to 5.5V DC

The HT12D has a wider operating voltage range, making it more versatile for different power sources. The HT12E is limited to 5V systems.

Latching Outputs

  • HT12D: Yes
  • HT12E: No

The HT12D contains latching outputs to hold data even when transmission stops. The HT12E does not have this feature.

Microcontroller Interface

  • HT12D: More complex
  • HT12E: Simpler, open-drain outputs

The HT12E is easier to interface with microcontrollers thanks to its open-drain outputs. The HT12D requires more components to interface.

Choosing Between HT12D and HT12E

So which encoder/decoder chip should you choose? Here are some guidelines:

  • For lower voltage systems under 5V, choose the HT12E. The 4.5V to 5.5V range makes it ideal for 5V microcontroller projects.
  • If you need latching outputs to store data, go with the HT12D. The HT12E does not have this capability.
  • For direct microcontroller interfacing, the HT12E is easier to work with. The HT12D needs extra components to interface.
  • For higher voltage systems up to 12V, the HT12D is the only choice. The HT12E cannot handle voltage above 5.5V.
  • Both chips consume very low power. Look at your voltage and interfacing needs to decide.

Example Projects

Here are some example projects you can create with these encoder/decoder pairs:

  • Remote control cars or boats
  • Garage door openers
  • Wireless alarm systems
  • Robotics remote control
  • Wireless sensors

The HT12D or HT12E handle encoding/decoding needs for the wireless data transmission in these systems.

Frequently Asked Questions

What is the main difference between HT12D and HT12E?

The main differences are the operating voltage range and output types. The HT12D works from 2.4V to 12V, while the HT12E works from 4.5V to 5.5V. The HT12D has latching outputs and the HT12E has simpler open-drain outputs.

How do I choose between HT12D vs HT12E?

Look at your voltage requirements and interfacing needs. HT12E is good for 5V systems with direct microcontroller connections. HT12D is better for a wider voltage range and if you need latching outputs.

Can I use both HT12D and HT12E together?

Yes, you can use an HT12E encoder with an HT12D decoder and vice versa. As long as the transmitted data format is the same, the encoder/decoder pairs will be compatible.

What data format do the HT12D and HT12E use?

Both chips use a 12-bit data word that includes 8 address bits and 4 data bits. This 12-bit data format allows the transmission of 16 different addresses and 16 data combinations.

What is the transmission distance for these encoder/decoder pairs?

The maximum transmission distance is approximately 100 meters. Factors like power supply, antenna quality, and environment can affect the usable range.

HT12 Encoder and Decoder

HT12 Encoder and Decoder

Overview of HT12 Encoders and Decoders

The HT12E encoder and HT12D decoder are commonly used in wireless transmission systems. They use Holtek’s 2^12 series encoders/decoders designed for remote control system applications.

The HT12E encoder converts parallel data into serial data which can be transmitted wirelessly. The HT12D decoder receives the serial data and converts it back into parallel data. They use Manchester encoding to improve transmission reliability.

Key Features

  • Enables wireless transmission of 12-bit parallel data
  • Built-in oscillator needs only 5V DC supply
  • Encoding enhances transmission reliability
  • Transmission distance up to 200m
  • Low standby current consumption

How an HT12 Encoder Works

The HT12E encoder has 12 parallel data input pins and 1 serial output pin. The steps in the encoding process are:

1. Parallel to Serial Conversion

The 12-bit parallel input data is converted to serial data for wireless transmission.

2. Manchester Encoding

The serial data bits are Manchester encoded before transmission. Each data bit is represented by a high to low (or vice versa) transition in the middle of the bit period.

This encoding improves reliability as any DC component is eliminated and clock recovery is possible from the transitions.

3. Oscillator Modulation

The encoded serial data stream is used to modulate the built-in oscillator to generate the final encoded carrier output signal.

How an HT12 Decoder Works

The HT12D decoder receives and decodes the wireless transmission from the encoder. The key steps are:

1. Carrier Demodulation

The decoder first demodulates the carrier signal to extract the encoded serial bit sequence.

2. Manchester Decoding

The Manchester encoded data is decoded to recover the original serial data stream.

3. Serial to Parallel Conversion

Finally, the serial data is converted to 12-bit parallel output data.

This matches the original 12-bit parallel data input to the encoder.

Typical Application Circuit

A typical application circuit uses an HT12E encoder and RF transmitter on the transmit side. The receiver side has an RF receiver and an HT12D decoder. The encoder and decoder are interfaced using their data pins.

Advantages of Using HT12E/HT12D

Some key advantages of using HT12E encoders and HT12D decoders:

  • Simple integration into wireless systems
  • Provides 12-bit parallel data interface
  • Transmission distances up to 200m
  • Enhanced transmission reliability
  • Low power consumption

They provide a convenient wireless transmission solution for 12-bit control or data applications.

Frequently Asked Questions

What is the maximum transmission distance using HT12E/HT12D?

The maximum transmission distance is typically 100-200m using a basic RF transmitter/receiver. With higher power transmitters and directional antennas, the range can be extended to 500m or more.

Does the encoder/decoder need any separate power supply?

No, the built-in oscillator generates the carrier signal and only needs a single 5V DC supply input. No other power supply is required.

Can the encoder/decoder pins be interfaced directly to a microcontroller?

Yes, both the encoder and decoder pins can be interfaced directly to a microcontroller for parallel data transfer. No additional interfacing circuitry is required.

What modulation type is used in the HT12E/HT12D?

They use OOK (On-Off Keying) modulation where the carrier is switched on and off based on the input serial data stream.

Is any programming required for the encoder/decoder to operate?

No programming is required. The encoder/decoder provide a fixed parallel data interface and wireless transmission. They operate standalone without any programming.

Decoding Infrared Remote Control Signals with IR Decoder ICs

Decoding Infrared Remote Control Signals with IR Decoder ICs

Infrared (IR) remote controls are everywhere – TVs, audio equipment, air conditioners all use IR remotes to control various functions. At the heart of these remotes and devices is the ir remote decoder ic. These chips take the modulated IR signal from the remote, decode it, and output the control commands to the rest of the appliance circuitry. In this article, we’ll look at common IR decoder ICs and how to use them in your next embedded project.

Common IR Decoder ICs

There are many decoder ICs to choose from. Here are some popular options:

TSOPXX38 Series

These are some of the most commonly used and inexpensive IR receiver modules. Key features:

  • TSOP17XX – receives IR up to 1MHz
  • TSOP48XX – receives IR up to 4MHz
  • Output is active low
  • Comes in convenient epoxy molded package

Vishay TSOP312XX Series

Higher performance and features than TSOPXX38 series:

  • Receives signals up to 4MHz
  • Higher sensitivity and ambient light immunity
  • Comes in leaded package for through-hole mounting

Vishay TSSP4038

Specialty IR receiver IC:

  • Receives signals up to 40MHz
  • High speed IR reception for RC hobby applications
  • Surface mount package
ICMax FrequencyOutputPackage
TSOP17381MHzActive LowEpoxy molded
TSOP48384MHzActive LowEpoxy molded
TSOP312364MHzActive LowLeaded
TSSP403840MHzActive LowSMD

Table: Comparison of common IR decoder ICs

Using an IR Decoder IC

Using an IR decoder IC is straightforward:

  1. Connect power and ground
  2. Add filtering capacitors for clean power
  3. Connect output pin to microcontroller input
  4. Add IR receiver LED aligned with line of sight
  5. Decode output signal transitions to recover control codes

Many modules like TSOPXX38 come pre-assembled with the IR receiver and capacitor filter. Otherwise, an IR photodiode or phototransistor is used. The output pin switches low when IR modulated light is detected. A microcontroller detects the pulse lengths and gaps to recover the underlying control signal.

With high speed decoders like TSSP4038, additional amplification may be needed before feeding the output to a microcontroller.

Example Projects

Some examples of how IR decoder ICs can be used:

  • IR remote spy – Log and analyze IR signals
  • Universal remote – Record and playback IR commands
  • IR to WiFi bridge – Control appliances over a network
  • IoT automation – Control appliances with smartphone apps

The wide variety of inexpensive decoder ICs make them easy to integrate into IoT and automation projects. With just a microcontroller and few other components, powerful IR remotes can be created.

Frequently Asked Questions

What is the maximum range for IR remotes?

Most IR remotes have a range of about 20-30 feet, depending on conditions. Range can vary based on transmitter power, receiver sensitivity, ambient light conditions, and alignment.

Can IR signals pass through walls?

No, IR signals cannot penetrate solid objects like walls. IR remotes require line-of-sight to function properly.

What carrier frequencies are typically used?

Most IR remotes modulate the signal onto a carrier between 30-60kHz. Higher frequencies up to 455kHz may also be used.

Is IR technology being replaced by RF?

In some applications, yes. RF remotes using Bluetooth and WiFi allow control without line-of-sight. However, simple IR remotes are still inexpensive and ubiquitous.

Can IR remotes interfere with each other?

Yes, many IR remotes use similar carrier frequencies. Physical blocking of signals is required to isolate remotes.

What is IC MT8870 Price

What is IC MT8870 Price

The MT8870 is an integrated circuit designed for DTMF tone decoding. It can detect and decode all 16 DTMF tone pairs into a 4-bit code. The MT8870 is commonly used in telephone dialing circuits for decoding the numbers pressed on a telephone keypad.

MT8870 Pricing Factors

There are several factors that affect the pricing of the MT8870 IC:

Manufacturing Cost

Like most integrated circuits, the manufacturing cost of the MT8870 depends on the complexity of the chip design and fabrication process. More complex ICs with smaller transistor geometries generally cost more to produce.


ICs are sold in different package types like DIP, SOIC, QFP, etc. The package type affects the price with smaller packages generally being more expensive. The MT8870 is commonly available in 16-pin DIP and SOIC packages.

Order Quantity

IC pricing is largely dependent on order volume. Buying ICs in bulk lowers the per unit cost. The MT8870 can range from around $1.5-$2 in single quantities to under $1 in large volumes.


There are different brands offering the MT8870 IC. While electrically equivalent, pricing can vary slightly between brands. Well-known suppliers include NXP, ON Semiconductor, Adafruit.

Current MT8870 Pricing

Here are some typical price ranges for the MT8870 based on order quantity:

1-9 units$1.5 – $2 per unit
10-99 units$1 – $1.5 per unit
100-999 units$0.75 – $1 per unit
1000+ unitsUnder $0.75 per unit

Prices will also depend on the distributor and packaging. When comparing prices, be sure to compare the same package type and order quantity range.

Uses for MT8870 ICs

Here are some common applications for the MT8870:

  • DTMF decoder in telephone dialing circuits
  • DTMF tone decoder in cell phones
  • DTMF tone detection for microcontrollers
  • DTMF tone extraction in voice mail systems
  • Decoding signals for remote controls
  • Frequency detection in electronic musical instruments

The MT8870 provides an affordable and reliable way to decode DTMF tones in a range of electronic devices. Its low cost makes it suitable for high volume commercial products.

Frequently Asked Questions

What is the difference between MT8870 and MT8870D?

The MT8870D is functionally equivalent to the MT8870 except it has much lower power consumption, around 1mA vs 2mA for the standard MT8870. The D version is more suitable for battery powered applications.

Are there alternatives to the MT8870 IC?

Some alternatives include the HT9170B DTMF receiver and M-8870 DTMF decoder ICs which provide similar DTMF tone decoding functionality. The Holtek HT9170B is comparable in pricing to the MT8870.

What package options are available for MT8870?

Common packaging options include 16-pin DIP, 16-pin SOIC, 18-pin SOIC, and custom SMT packages. DIP and SOIC through-hole packages are widely available while SMT provides a compact surface mount option.

Is the MT8870 only used for DTMF decoding?

The primary function of the MT8870 is DTMF tone decoding. However, it can also be used as a general dual-tone decoder for detecting other frequencies outside the DTMF spectrum.

What is the typical supply voltage range for MT8870?

The supply voltage range is 3V to 5.5V. It can operate down to 2.4V at slower speeds. 5V is the most common supply voltage used.

How to crack cm8870 ic

How to crack cm8870 ic

The CM8870 is an integrated circuit chip manufactured by Philips Semiconductors. It contains a touch decoder that interprets x-y coordinates from a touch screen panel. Cracking this IC means deciphering its functionality and replicating it. Here is a step-by-step guide on how to crack the CM8870 IC.

Gather Required Tools and Equipment

To crack the CM8870 IC, you will need the following tools:

  • Soldering iron and solder
  • Multimeter
  • Oscilloscope
  • IC sockets
  • Breadboard
  • Jumper wires
  • PC with USB interface

It is also recommended to have basic electronic skills and knowledge of circuits and soldering.

De-cap the IC

The first step is to carefully remove the plastic encapsulation from the IC chip. This process is known as decapsulation or de-capping. It will expose the silicon die inside the IC package. There are a few methods to de-cap ICs:

  • Mechanical abrasion – Removing the packaging using sandpaper or a knife. Risks damaging the silicon.
  • Chemical dissolution – Immersing the IC in acids like nitric acid to dissolve the packaging. Needs safety equipment.
  • Thermal shock – Alternately heating to brittleness and rapid cooling. Works for plastic packaged ICs.

Take precautions not to damage the tiny structures and wire bonds on the extracted silicon die.

Analyze the Die Structures

Once the IC die is exposed, analyze it under a microscope to identify key functional blocks and structures. Look for:

  • Rectangular functional blocks
  • Wires connecting blocks
  • Markings from manufacturing process

Also use magnification, staining, and chemical etching if needed to reveal more details.

Die Analysis of CM8870

The CM8870 die contains these key blocks:

Analog frontendTouch detection and A/D conversion
MicrocontrollerCoordinate calculation and processing
MemoryProgram and data storage
I/O controlInterface to external system

Determine Pinouts

Identify the function of each pin on the IC package using the exposed die and datasheet. Use multimeter probes to trace connections from each die block to the pin pads.

For CM8870, important pins include:

  • VDD and VSS for power supply
  • XI and XO for external crystal
  • Y+ and Y- for touch signals
  • I/O ports for digital signals

Tabulate the pinouts for reference.

Replicate Functionality

After analyzing the IC, the next step is to replicate its functionality with basic electronic components.

For CM8870, this may involve:

  • Op amps to detect and amplify touch signals
  • ADC and microcontroller for coordinate calculation
  • Memory chips to store program instructions
  • Discrete logic gates for I/O control

Build the circuity on a breadboard and verify it works before creating your own PCB.

Testing and Applications

Once the IC functionality has been cracked and replicated, test it thoroughly across different conditions. Try different touch screens, power supplies, controller interfaces etc.

The replicated IC can then be used in place of CM8870 in touch screen designs. It can help repair devices or build new ones without requiring the original ICs.

Some applications include:

  • Touchscreen kiosks and displays
  • Tablets and handheld devices
  • Industrial touchscreen HMIs
  • Arcade machines

Frequently Asked Questions

Here are some common questions about cracking the CM8870 IC:

Q: Is reverse engineering ICs legal?

A: Laws vary by country. In some cases, reverse engineering chips for research or repair purposes is allowed under fair use exemptions. But duplicated commercial use may violate copyrights. Seek legal counsel before proceeding.

Q: How long does it take to crack an IC?

A: It depends on the complexity, but simple ICs like CM8870 may be cracked in a few days by an experienced engineer. More complex ICs with billions of transistor could take weeks or months.

Q: Does cracking an IC require expensive equipment?

A: Basic tools like multimeters and microscopes are accessible to hobbyists. But advanced techniques like SEM, FIB, AES need expensive setups costing over $100k.

Q: Can the original IC design files be recovered?

A: Reverse engineering can only recover a logical representation of the chip components and connectivity. The original HDL or GDSII layout files remain proprietary.

Q: What are the alternatives to cracking ICs?

A: Emulation using FPGAs, simulating the IC, finding drop-in replacement ICs, or seeking manufacturer datasheets. But cracking provides most insight.

An Introduction to Encoder-Decoder IC Pairs

An Introduction to Encoder-Decoder IC Pairs

What are Encoder-Decoder IC Pairs?

Encoder-decoder IC pairs are integrated circuits that work together to translate input signals into output signals. The encoder IC converts the input data into a encoded format, while the decoder IC converts the encoded data back into the original format.

Encoder-decoder ICs are commonly used for:

  • Digital communications, such as modems and radio frequency communications
  • Data storage, such as disk drives and tape drives
  • Display interfaces, such as HDMI and VGA
  • Automotive systems, such as engine control units

Some common encoder-decoder IC pairs include:

  • HDMI encoder and HDMI decoder
  • CAN bus transceiver
  • SATA host controller and SATA device

How Do Encoder-Decoder ICs Work?

The encoder IC takes the input data and encodes it into a different format using a specified encoding scheme. This is done for various reasons, such as to compress the data, improve signal integrity, or interface with transmission standards.

Some common encoding schemes used by encoder ICs include:

  • Pulse-code modulation (PCM)
  • Delta modulation
  • Manchester encoding
  • 8b/10b encoding

The encoded data is then transmitted over a channel or interface. At the receiving end, the decoder IC reverses the encoding process to recover the original data. The decoder applies the same encoding scheme to correctly interpret the encoded data.

Proper encoding and decoding ensures that data is transmitted accurately across interfaces and channels. The encoder-decoder pair work together to maintain data integrity from input to output.

Key Applications of Encoder-Decoder ICs

Encoder-decoder ICs are ubiquitous in modern digital systems and find many applications:

Data Communications

  • Modems use encoder-decoder ICs to convert digital data to analog signals for transmission over phone lines. Decoders recover the digital data at the receiving modem.
  • Wireless radios encode data into RF signals using encoders. The data gets decoded back to digital at the receiving end.

Data Storage

  • Hard disk and tape drives use encoder-decoder ICs. The encoder converts digital data into patterns written on the storage media. The decoder reads these patterns to recover the original data.

Display Interfaces

  • HDMI, DVI, and VGA use encoder-decoder ICs to transmit high resolution video between sources and displays. Video gets encoded into the interface’s signaling scheme and decoded back to video.

Automotive Systems

  • CAN bus transceivers encode CAN messages from the ECU and decode messages received from the CAN bus back to digital data.

Key Specifications of Encoder-Decoder ICs

Engineers evaluate encoder-decoder ICs based on parameters such as:

  • Data rate – The maximum data rate supported in bits per second (bps). Higher data rates are required for high-speed interfaces.
  • Supported protocols – Protocols like SPI and I2C that the ICs can encode/decode.
  • Error correction – Whether the IC has error correction capabilities to detect and fix corrupted data.
  • Power consumption – Lower power usage allows integration into portable and battery operated devices.
  • Package type – Common form factors include DIP, SOIC, QFN to allow integration into different circuit designs.
  • Operating temperature – Industrial and automotive encoder-decoder ICs operate at higher temperature ranges.
  • Programming interfaces – Some encoders and decoders allow programming options via I2C, SPI interfaces.

Understanding these specifications help pick the right encoder-decoder pair for an application based on interface data rate, protocols, error tolerance and other requirements.


Encoder-decoder ICs enable the transmission of data across various interfaces and channels by converting the data into encoded formats. They are an essential component in communications, storage, display, automotive, industrial systems and countless electronic devices. Engineers select the right encoder-decoder pair based on data rate, interface, error tolerance, operating conditions, and other parameters of their system. With the continued growth in digital data, encoder-decoder ICs will remain indispensable for interfacing, transmitting and storing data.

Frequently Asked Questions

Q: What is the difference between an encoder and a multiplexer?

A: An encoder converts data into a different format using an encoding scheme, while a multiplexer combines multiple input signals into a single output signal. Encoders transform the data for transmission or storage, while multiplexers aim to share a channel between multiple input sources.

Q: What types of interfaces use encoder-decoder ICs?

A: Common interfaces using encoder-decoder ICs include HDMI, DVI, VGA, Ethernet, USB, SATA, PCIe, DisplayPort, CAN Bus, SPI, I2C, automotive communication buses, and many more.

Q: How do encoder ICs add error correction capabilities?

A: Some encoders add parity bits, cyclic redundancy checks or other checksums to the encoded data for error detection. The decoder IC uses these to detect and even correct corrupted bits in some cases.

Q: What is the function of clock and data recovery in decoder ICs?

A: Clock and data recovery extracts the clock timing information from received data to generate a synchronized clock. This allows the decoder to reliably sample the incoming data and correctly decode it.

Q: Why are encoder-decoder ICs required for displays and video interfaces?

A: Displays need high speed transmission of pixel data. Encoder ICs compress and convert this into the display interface’s signaling method. The decoder ICrecovers the pixel data to drive the display. This allows high resolution video transmission over the interface.

4 to 16 Line Decoder ICs

4 to 16 Line Decoder ICs

Introduction to 4 to 16 Line Decoder ICs

A decoder is a combinational circuit that converts binary information from the input lines to a specific output line. 4 to 16 line decoders have 4 input lines and 16 output lines. They take a 4-bit binary input and activate one of the 16 output lines.

Decoders are used in various applications like memory addressing, multiplexing, and seven segment displays. Some common ICs used as 4 to 16 line decoders are 74154, 74LS154, CD4514B, MC14514, etc.

How 4 to 16 Line Decoders Work

A 4 to 16 decoder has 4 input lines (A, B, C, D) and 16 output lines (Y0 to Y15). The truth table below shows the working of a 4 to 16 decoder:


Based on the binary input at A, B, C, D pins, the corresponding output line is activated HIGH while other lines are LOW.

Features of 4 to 16 Line Decoder ICs

Some notable features of 4 to 16 line decoder ICs are:

  • All outputs are active LOW, i.e. output is LOW when selected
  • Output enable pin (E) to disable all outputs
  • Complementary outputs in some ICs
  • Ability to cascade two 4 to 16 decoders to obtain a 8 to 256 decoder
  • Wide operating voltage range (3V to 18V)
  • High current drive capacity (25mA)
  • High speed operation (10MHz)
  • Low power consumption

Applications of 4 to 16 Line Decoder ICs

Some major applications of 4 to 16 line decoder ICs include:

  • Memory addressing – To decode address bus bits for memory chip selection
  • Seven segment displays – To decode BCD inputs and drive seven segment displays
  • Demultiplexing – Converting multiple inputs into a single output line
  • Peripheral selection – Choosing between various peripheral devices
  • Waveform generation – Generating different waveforms from binary inputs

Comparison Between Popular 4 to 16 Decoder ICs

Supply Voltage4.5V to 5.5V3V to 18V3V to 15V
Propagation Delay15ns50ns100ns
Output Current25mA25mA5mA
Power Dissipation135mW330mW100mW
Temperature Range0°C to 70°C-55°C to 125°C-55°C to 125°C

Frequently Asked Questions

What is the difference between a decoder and a demultiplexer?

A demultiplexer converts one input into multiple outputs whereas a decoder converts binary inputs into a single output. Demultiplexer is mostly used for data routing while decoder is used for memory addressing.

How do I cascade two 4 to 16 decoders?

The outputs of the first 4 to 16 decoder can be fed as inputs to the second decoder. An enable pin can be added between the decoders. This results in a total of 16*16 = 256 outputs with 8 input pins.

Can unused outputs of the decoder be left floating?

No, unused outputs should be connected to ground through a resistor. A floating output may oscillate and cause unwanted transitions.

What are the advantages of active low outputs in decoders?

Active low outputs allow the outputs to be ORed or NORed if required. This is useful in memory decoding to select multiple chips. Active high outputs cannot be directly ORed.

How do I choose the right decoder IC for my application?

Consider voltage levels, output drive capacity, speed, power dissipation, and cost. Analyze the loading on each output to determine the drive needed. Also look for complementary outputs if active high levels are needed.