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Interview Questions – I2C

Here are the frequently asked 50+ Interview Questions about I2C

I2C Interview Questions 01 to 03

What does I2C stand for?

I2C stands for Inter-Integrated Circuit.


What is its purpose?

The purpose of I2C is to provide a simple and efficient way for multiple digital integrated circuits to communicate with each other, using a minimal number of wires. It’s commonly used for communication between microcontrollers, sensors, and other peripheral devices in embedded systems. I2C facilitates serial communication, allowing devices to share data and commands in a master-slave or multi-master configuration.


Explain the basic working principle of I2C.

Step Description
Start Condition Master pulls SDA low while SCL is high, signaling the beginning.
Addressing Master sends the address of the target slave (7 or 10 bits).
Read/Write Bit Master sends a Read/Write bit, indicating the direction of data flow.
Data Transmission 8 bits of data are sent, with each bit synchronized by the clock.
Acknowledgment (ACK) Receiver pulls SDA low during the ACK bit if ready for more data.
Repeated Start Condition Master can send another start condition without a stop.
Stop Condition Master releases SDA from low to high while SCL is high, signaling the end.


I2C Interview Questions 04 & 05

What are the key components in an I2C communication system?

Component Description
Master The device initiating communication and controlling the bus. It generates the clock signal.
Slave A device that responds to the master’s commands.
SDA (Serial Data Line) Bidirectional line for transmitting data between the master and slave.
SCL (Serial Clock Line) Carries the clock signal generated by the master, synchronizing data transmission.
Pull-up Resistors Connected to SDA and SCL lines to pull them high when not actively transmitting.
Start Condition A unique sequence that signals the beginning of a data transfer.
Stop Condition Marks the end of a data transfer on the bus.
Acknowledge (ACK) A bit indicating successful reception of data by the receiver.
NACK (Not Acknowledge) Indicates that the receiver did not successfully receive the data.
Bus Arbitration Mechanism for resolving conflicts when multiple masters attempt to access the bus.


What is the difference between master and slave devices in I2C?

Characteristic Master Device Slave Device
Role Initiates and controls communication on the bus. Responds to commands and data from the master.
Clock Generation Generates the clock signal for data synchronization. Does not generate the clock signal; synchronizes with the master’s clock.
Initiation Initiates communication by sending start and stop conditions. Waits for commands and data from the master; does not initiate communication.
Addressing May address multiple slave devices on the bus. Has a specific address and responds when addressed by the master.
Control Dictates overall timing and flow of data transfer. Follows the instructions provided by the master.


I2C Interview Questions 06

How does arbitration work in I2C?

Aspect Description
Bus Arbitration Mechanism to resolve conflicts when multiple masters try to access the I2C bus simultaneously.
Priority Determination Based on clock stretching: If two masters attempt to send data simultaneously, the master driving the bus low (sending ‘0’) has higher priority.
Clock Stretching Winning master continues its transmission, while the losing master releases control by holding the clock line low (clock stretching).
Bus Free Condition After communication and stop condition, the bus enters a “bus free” state, and any device can initiate communication.
Resolution of Conflicts Losing master retries communication when the bus is free, minimizing collisions and ensuring data integrity.

This table provides a concise overview of how arbitration works in I2C, emphasizing the prioritization based on clock stretching and the resolution of conflicts during simultaneous master access.


I2C Interview Questions 07

What is the significance of pull-up resistors in an I2C bus?

Aspect Description
Bus Line Voltage Levels Pull-up resistors ensure proper voltage levels on the Serial Data Line (SDA) and Serial Clock Line (SCL).
High and Low States They help establish logical ‘1’ (high) and logical ‘0’ (low) states on the bus lines.
Preventing Bus Contention Pull-up resistors prevent bus contention by ensuring the lines are pulled high when not actively driven low by a device.
Synchronization Aid in synchronizing devices on the bus, facilitating proper timing during data transmission.
Noise Immunity Improve noise immunity by minimizing the impact of external interference on the bus lines.
I2C Specifications Compliance Proper pull-up resistor values ensure compliance with I2C standards and specifications.


I2C Interview Questions 08 & 09

What is clock stretching in I2C, and why is it used?

Aspect Description
Definition Clock stretching is a mechanism in I2C where a slave device delays the clock signal (SCL) to gain additional processing time.
Purpose 1. Slave Readiness: Allows slower or resource-limited slaves to catch up with data processing.
  2. Synchronization: Maintains synchronization between master and slave during data transfer.
  3. Flow Control: Prevents overwhelming a slave with data, providing a form of flow control.
  4. Real-Time Processing: Accommodates devices needing real-time processing or event response.
  5. Error Handling: Enables slaves to signal errors or exceptional conditions during communication.


How many devices can be connected to a single I2C bus?

The number of devices that can be connected to a single I2C bus depends on various factors, including the addressing scheme used and the electrical characteristics of the connected devices. In a standard 7-bit addressing scheme, there are 128 possible addresses (0 to 127). However, some addresses are reserved, so the practical limit is usually lower


I2C Interview Questions 10

What is the maximum distance for reliable communication on an I2C bus?

the maximum distance for reliable communication on an I2C bus might be challenging because it depends on various factors and can vary significantly based on the specific conditions of the system. However, I can provide a table outlining some factors influencing I2C communication distance:

Factor Influence on Maximum Distance
Cable Length and Capacitance Longer cables and higher capacitance can limit distance.
Pull-Up Resistor Values Higher values may limit distance by slowing signal transitions.
Signal Integrity Impacts the ability to accurately interpret signals.
Bus Frequency Higher frequencies may limit distance due to faster signal edges.
Buffering and Repeaters Use of buffers or repeaters can extend the communication distance.
I2C-bus Extenders and Converters Specialized devices designed to extend the reach of I2C signals.

This table highlights the factors that can influence the maximum distance for reliable communication on an I2C bus. Keep in mind that specific values and distances would need to be determined based on the particular characteristics of the system and the devices used. Always refer to the datasheets and specifications of the components for accurate information.


I2C Interview Questions 11 & 12

Explain the difference between I2C and SPI.

Characteristic I2C SPI
Number of Lines 2 (SDA, SCL) 4 (MOSI, MISO, SCK, SS/CS)
Topology Multi-master, master-slave architecture Master-slave architecture with separate SS/CS lines
Addressing 7-bit or 10-bit addressing schemes Typically uses SS/CS lines for device addressing
Data Transfer Bidirectional; packet-based with start, stop, and acknowledge bits Full-duplex; simultaneous send and receive
Clocking Shared clock line (SCL) Individual clock lines for each device
Speed Generally lower frequencies Can operate at higher clock frequencies
Hardware Complexity Requires fewer pins and simpler hardware May require more pins, especially with multiple devices
Application Examples Sensors, EEPROMs, real-time clocks Flash memory, display controllers, ADCs


What is the purpose of the Start and Stop conditions in I2C communication?

Condition Purpose
Start Condition   Initiation: Marks the beginning of an I2C communication transaction.
Signal Generation: Generated by the master pulling SDA low while SCL is high.
Functionality: Notifies devices on the bus of the start of a new communication session. Allows the master to address a specific slave or broadcast a general call address.
Stop Condition    Termination: Signals the end of an I2C communication transaction.
Signal Generation: Generated by the master releasing SDA from low to high while SCL is high.
Functionality: Indicates the completion of data transmission. Frees the bus for other devices to initiate communication.
Combined Functionality: Defines the boundaries of a data transfer sequence.


I2C Interview Questions 13

How do you calculate the maximum achievable data rate in I2C?

Factor Description
Clock Frequency (SCL) The primary factor; higher frequencies allow for faster data transfer.
Bus Capacitance Total capacitance of bus lines; higher capacitance can limit data rate.
Pull-Up Resistor Values Resistance values impact signal rise time; lower values support higher data rates.
Rise/Fall Time Requirements Compliance with I2C specifications; faster times allow for higher data rates.
Bit Time (tbit) Time taken for one bit; is influenced by clock frequency, rise/fall times, and more.
Maximum Achievable Data Rate
Calculated using BaudRate=1/tbit

While the actual calculation involves a formula for bit time and baud rate, this table highlights the key factors that contribute to the determination of the maximum achievable data rate in I2C communication. Remember to consult the datasheets and specifications of the I2C devices for accurate parameter values.

 
 


I2C Interview Questions 14

Explain the role of ACK (acknowledge) in I2C communication.

Aspect Description
ACK/NACK Generation After each byte transmission, the receiver generates either ACK (acknowledge) or NACK (not acknowledge) during the acknowledge bit time.
Confirmation of Reception ACK serves as confirmation that the transmitted data byte was received successfully without errors.
Error Checking NACK is generated if there is an issue or if the receiver did not correctly receive the data, indicating a potential error.
Signaling Further Steps In master-slave communication, the master’s ACK indicates an expectation of more data or commands from the slave.
Stop Condition After ACK The receiver, after sending ACK, participates in generating the Stop condition, indicating the end of data transmission.
Role in Data Integrity Crucial for ensuring the integrity of the data transfer by confirming successful reception.


I2C Interview Questions 15 & 16

What are repeated start conditions in I2C?

Aspect Description
Definition A repeated start condition is a special condition in I2C where the master generates a start condition without first generating a stop condition.
Signaling The master device, after initiating a data transfer with a start condition, can send another start condition without sending a stop condition in between.
Purpose Allows the master to maintain control of the bus and continue communication without releasing it.
Sequential Transactions Useful for performing sequential transactions with a slave without relinquishing control of the bus.
Repeated Start vs. Stop This contrasts with a stop condition, which typically marks the end of a data transfer and releases the bus.
Timing Considerations Repeated starts introduce additional timing considerations and must comply with I2C specifications.


How does clock synchronization occur in I2C?

Aspect Description
Start Condition Initiated by the master, signaling the beginning of a communication sequence.
Clock Generation by Master The master generates the clock signal (SCL), controlling the frequency and timing of clock pulses.
Slave Clock Synchronization Slaves synchronize their internal clocks to the rising and falling edges of the master’s clock pulses.
Data Bit Transmission Both master and slave transition data on the Serial Data Line (SDA) synchronized with clock pulses.
Acknowledge (ACK) Bit Generated by the receiver (master or slave) synchronized with the clock to confirm successful data reception.
Stop Condition Initiated by the master, signaling the end of a communication sequence.

This table provides a concise overview of how clock synchronization occurs in I2C, highlighting key aspects such as start condition, clock generation, slave synchronization, data transmission, ACK bit, and stop condition


I2C Interview Questions 17

What is clock skew, and how does it impact I2C communication?

Aspect Description
Definition Clock skew refers to the variation in the arrival times of clock signals at different components in a system.
Causes – Variations in trace lengths. – Manufacturing tolerances in clock generators. – Differences in propagation delays.
Impact on I2C Negative Impact: Can lead to timing misalignment between master and slave devices, causing data transmission errors.
Clock Edges Misalignment Clock skew may result in misalignment between clock edges, affecting the accuracy of bit transitions on the data line.
Data Validity Issues Skewed clock edges can cause data setup and hold time violations, impacting the validity of data read or written.
Timing Violations Violations of I2C timing specifications may occur, leading to unreliable communication and potential data corruption.
Minimizing Clock Skew – Use controlled impedance traces. – Minimize trace lengths. – Choose clock sources with low variability. – Proper signal integrity practices.
Solutions – Signal conditioning techniques. – Synchronization mechanisms. – Clock distribution strategies to reduce skew.


I2C Interview Questions 18

Can multiple masters exist on the same I2C bus? If so, how is conflict resolved?

Aspect Description
Multiple Masters I2C supports the existence of multiple masters on the same bus. Each master can initiate communication independently.
Bus Arbitration Bus arbitration is the mechanism used to resolve conflicts when multiple masters attempt to access the bus simultaneously.
Priority Determination Priority is determined based on the concept of clock stretching. The master driving the bus low has higher priority.
Clock Stretching The winning master (higher priority) continues transmission, while the losing master releases control by holding the clock line low.
Resolution of Conflicts Winning master completes transmission, and the losing master retries its communication after the bus is free.
Bus Free Condition After a complete communication sequence and Stop condition, the bus enters a “bus free” state, allowing any device to initiate communication.
Retry Mechanism The losing master retries communication when the bus is free, minimizing collisions and ensuring data integrity.


I2C Interview Questions 19

What is the purpose of the General Call Address in I2C?

Aspect Description
Definition The General Call Address is special (0x00) in I2C that can be used to address all devices on the bus simultaneously.
Purpose    1. Broadcast Communication: Enables the master to send a command or data to all devices on the bus simultaneously.
2. Addressing Multiple Slaves: Useful for scenarios where multiple identical slave devices exist on the bus.
3. Configuration Commands: Allows sending configuration commands that are relevant to all devices on the bus.
4. Group Operations: Facilitates group operations or commands that involve all devices connected to the I2C bus.
Use in Slave Devices Slaves can respond to the General Call Address if they are configured to recognize and respond to it.
Acknowledgment Slaves responding to the General Call Address should acknowledge the command or data sent by the master.
Bus Free Condition After the General Call Address is used, the bus enters a “bus free” state, and individual addressing can resume.


I2C Interview Questions 20

Explain the difference between 7-bit and 10-bit addressing in I2C.

Characteristic 7-Bit Addressing 10-Bit Addressing
Address Length 7 bits 10 bits
Number of Addresses 2 Power 7=128, 2 Power 7=128 addresses 2 Power 10=1024, 2Power 10=1024 addresses
Standard Format Standard and widely used format Extended format, less commonly used
Format in Transaction MSB (Most Significant Bit) is the Read/Write bit (R/W), followed by 7 address bits MSB (R/W) followed by 2 additional address bits and then 8 address bits
Address Range 0x00 to 0x7F (0 to 127 in decimal) 0x000 to 0x3FF (0 to 1023 in decimal)
Compatibility Widely supported by most I2C devices Supported by fewer devices; may not be supported in all applications
Device Identification Limited to 128 devices on a bus with unique 7-bit addresses Supports a larger number of devices (up to 1024) with unique 10-bit addresses
Reserved Addresses Some addresses are reserved for special purposes A larger range of addresses, providing more flexibility


I2C Interview Questions 21

How does I2C handle bus collisions?

Aspect Description
Start Condition Initiated by a master to begin communication.
Clock Stretching Mechanism where devices can stretch the clock line to indicate bus ownership and resolve collisions.
Priority Determination Determined by the master driving the bus low (sending a ‘0’) during clock stretching, granting it higher priority.
Resolution of Conflicts Winning master continues transmission; losing masters release control, wait until the bus is free, and retry later.
Retry Mechanism Devices that lost in arbitration can retry their communication when the bus is free.
Bus Free Condition After a complete communication sequence and Stop condition, the bus enters a “bus free” state for the next initiation.
Clock Synchronization Ensures devices synchronize their clocks to the master’s clock pulses, preventing timing-related collisions.


I2C Interview Questions 22

What is the purpose of the NACK (not acknowledge) condition in I2C?

Aspect Description
Signaling Indicates that the received data byte was not successfully acknowledged by the receiving device.
End of Data Transmission Marks the completion of data transmission for a particular byte in I2C communication.
Slave Unavailability Used by a slave device to indicate that it is not ready to receive more data or process the current data.
No Matching Address/Command Indicates that the address or command provided by the master does not match the expectations of the slave.
Error Indication Serves as an indication of an error or unsuccessful attempt at communication between the master and slave.
Conditional Acknowledgment Allows conditional acknowledgment or rejection of specific data based on device-specific conditions.
Bus Free Condition In master-to-master communication, can indicate that the bus is free for another master to take control.
Stop Condition After NACK In a master-to-slave communication sequence, the master may generate a Stop condition after receiving a NACK.


I2C Interview Questions 23 & 24

What are the typical voltage levels used in I2C communication?

Aspect Description
High Level (Logic ‘1’) Typically the supply voltage (�DDVDD or �CCVCC). Commonly 3.3V or 5V, depending on the device’s power supply.
Low Level (Logic ‘0’) Usually close to the ground reference (0V). Commonly 0V (ground).
Voltage Margin Tolerance for variations in high and low levels.
Recognition Thresholds Devices recognize high and low levels based on certain voltage thresholds.
Compatibility Devices are designed to be compatible with different voltage levels.
Bus Pull-Up Voltage The voltage when the bus is idle, determined by pull-up resistors. Common values are 3.3V or 5V, depending on the system voltage.


Explain clock stretching and its impact on I2C timing.

Aspect Description
Mechanism Clock stretching is a mechanism where a slave device holds the Serial Clock Line (SCL) low, temporarily extending the clock period.
Conditions for Stretching Can occur at any point during the transmission of a byte or transaction when the slave needs more processing time or is not ready to receive more data.
Impact on Timing Slows Down Data Transfer: Introduces additional delays in the clock period, impacting the overall timing of I2C communication.
Master Response The master must recognize clock stretching and wait until the slave releases the clock line before continuing with communication.
Importance for Real-Time Systems Critical consideration in real-time systems where precise timing is crucial for reliable operation.
Handling in Software Software on the master needs to be aware of clock stretching and implement appropriate mechanisms for handling delays.
Flexibility Provides flexibility for slower or less responsive devices to participate in the communication without timing constraints.
System Design Impact Requires careful consideration in system design, especially in real-time applications, to ensure predictable operation.


I2C Interview Questions 25

How do you troubleshoot I2C communication issues?

Step Description
1. Check Physical Connections Ensure secure and correct wiring, and verify the placement of pull-up resistors.
2. Verify Power Supply Confirm stable and adequate power supply for all devices on the I2C bus.
3. Addressing Issues Verify unique and correct addresses for each device; ensure the master addresses the intended slave.
4. Check Clock and Data Lines Monitor clock (SCL) and data (SDA) lines using an oscilloscope or logic analyzer.
5. Clock Synchronization Confirm proper clock synchronization and check for clock stretching issues.
6. Bus Capacitance Reduce bus capacitance if excessive, minimizing cable length or using lower capacitance cables.
7. Device Status and Acknowledgments Verify device responses, check for NACK conditions, and analyze their causes.
8. Logic Analyzer or Oscilloscope Use tools to capture and analyze I2C bus waveforms, looking for unexpected transitions or noise.
9. Check Pull-Up Resistor Values Verify pull-up resistor values are within the recommended range to prevent signal degradation.
10. Review Datasheets Refer to device datasheets to ensure correct configuration settings, timing requirements, etc.
11. Isolate Devices Temporarily isolate devices to identify if a specific device is causing communication issues.
12. Firmware and Software Debugging Review and debug the firmware or software controlling I2C communication.
13. Grounding Issues Ensure proper grounding practices, with devices sharing a common ground reference.
14. Consider External Factors Account for external factors like electromagnetic interference (EMI) or nearby high-frequency signals.
15. Firmware Debugging Use debugging tools and logs to analyze firmware code, checking for error codes, timeouts, etc.


I2C Interview Questions 26

What is the role of the I2C bus capacitance, and how does it affect communication?

Aspect Description
Definition I2C bus capacitance refers to the total capacitance of the interconnected devices and the bus lines.
Impact on Communication  Signal Degradation: Excessive bus capacitance can lead to signal degradation and slow signal transitions.
Signal Integrity Issues: High capacitance can cause reflections and distortions, affecting signal integrity.
Timing Issues  Increased Rise and Fall Times: Higher capacitance results in increased rise and fall times of the signals.
Timing Violations: Can lead to timing violations, affecting the accuracy of data transmission.
Pull-Up Resistor Values Adjustment Required: Higher bus capacitance may require adjustment of pull-up resistor values to maintain signal integrity.
Bus Length Impact on Bus Length: Excessive capacitance limits the allowable bus length for reliable communication.
Capacitance Minimization   Best Practices: Minimizing bus capacitance is a best practice for maintaining signal quality in I2C communication.
Twisted Pair Wiring: Using twisted pair wiring helps reduce capacitance and improve signal integrity.
Low Capacitance Cables: Choosing cables with low capacitance contributes to better communication reliability.


I2C Interview Questions 27 & 28

Describe the I2C protocol in terms of data and clock lines.

Aspect Description
Data Line (SDA)   – Bidirectional Communication: SDA is bidirectional, used for transmitting control information and data between the master and slaves.
– Open-Drain or Open-Collector Configuration: Devices can actively pull SDA low, but external pull-up resistors passively pull it high when not transmitting.
– Start and Stop Conditions: Communication begins with a Start condition (SDA low while SCL is high) and ends with a Stop condition (SDA high while SCL is high).
Clock Line (SCL)   – Unidirectional Clock Signal: SCL is unidirectional, generated by the master, providing clock pulses for synchronous communication.
– Controls Data Transitions: Data on SDA is sampled and changed on the edges of SCL clock pulses.
– Start and Stop Conditions: SCL initiates and terminates communication with Start and Stop conditions.
Data Transmission   – Byte-Oriented Communication: Data is transmitted in 8-bit bytes, each followed by an acknowledge bit (ACK/NACK).
– MSB-First Transmission: Most Significant Bit (MSB) is transmitted first in each byte.
– Acknowledgment: After each byte, the receiver acknowledges with a low SDA during the acknowledge bit.
Addressing  – 7-bit or 10-bit Addressing: Devices use 7-bit or 10-bit addresses in the address frame.
– Address Frame: Consists of an address (7-bit or 10-bit) followed by a Read/Write bit (R/W).
Clock Stretching – Slave Control over SCL: A slave can hold the SCL line low (clock stretching) to slow down communication.


I2C Interview Questions 29

How is a repeated start condition different from a regular start condition in I2C?

Aspect Regular Start Condition Repeated Start Condition
Initiation – Initiates the beginning of a new I2C communication sequence. – Initiates a new data transfer within the same communication sequence without releasing control of the bus.
Timing – Occurs at the beginning of a communication sequence, typically before transmitting the slave address. – Can occur at any point after the initial start condition, allowing the master to send additional data to the same slave without readdressing.
Purpose – Marks the beginning of a new transaction with a different slave or a different type of operation (read or write). – Enables the master to send multiple sets of data or commands to the same slave without releasing control of the bus.
Use in Communication – Typically used when transitioning between different slaves or operations within the same communication sequence. – Used when continuous communication with the same slave is required without relinquishing control of the bus.
Bus Control After Start – After a regular start, the master has control of the bus and can address a different slave or perform a different operation. – After a repeated start, the master maintains control of the bus and can immediately transmit data to the same slave.

In summary, while both regular and repeated start conditions initiate I2C communication sequences, a regular start is commonly used to mark the beginning of a new transaction with a different slave or operation. In contrast, a repeated start is employed when the master needs to send additional data to the same slave without releasing control of the bus. The timing and purpose of these conditions play a key role in organizing and optimizing I2C communication


I2C Interview Questions 30

Can you use I2C for long-distance communication? Why or why not?

In table form to explain why I2C is not suitable for long-distance communication:

Aspect I2C for Long-Distance Communication
Signal Degradation – I2C signals are susceptible to degradation over long distances due to impedance and capacitance effects.
Pull-Up Resistor Values – Use of pull-up resistors contributes to overall bus impedance, affecting signal integrity over extended lengths.
Limited Bus Length – I2C specification recommends relatively short bus lengths to maintain reliable communication. Longer distances can result in increased capacitance and impedance, impacting signal quality and timing.
Clock Frequency Considerations – Clock frequency is affected by bus capacitance and rise/fall times. Longer distances may require lower clock frequencies to maintain reliable communication, reducing data transfer rates.
Lack of Differential Signaling – I2C does not use differential signaling, which is beneficial for noise immunity over longer distances.
No Active Signal Boosting – I2C lacks built-in mechanisms for active signal boosting or equalization, common in protocols designed for long-distance communication.
Sensitivity to Noise – I2C is sensitive to noise and electromagnetic interference, making it susceptible to issues over extended distances.


I2C Interview Questions 31

Explain the difference between a unidirectional and bidirectional I2C bus.

Aspect Unidirectional I2C Bus Bidirectional I2C Bus
Data Transmission – Data transmission occurs in one direction only, either from the master to slaves or from slaves to the master. – Data transmission is bidirectional, allowing communication in both directions. Both master-to-slave and slave-to-master data transfer are supported.
Primary Data Line – Typically, the Serial Data (SDA) line is used primarily for sending data in the specified direction. – SDA serves as the bidirectional data line, allowing devices to transmit and receive data.
Clock Line Role – Serial Clock (SCL) line provides clock pulses for synchronization in the specified direction. – SCL continues to provide clock pulses for synchronization in both directions.
Commonality – Less common configuration, used in specific applications with predominantly one-way data flow. – More common and widely used configuration, supporting bidirectional communication in most applications.
Flexibility – May be suitable for applications where unidirectional data flow aligns with the system requirements. – Provides greater flexibility and versatility, accommodating bidirectional communication needs.
I2C Standard Support – Compliant with the I2C standard but may have specific configurations based on the application. – Conforms to the standard I2C protocol, supporting both unidirectional and bidirectional communication as specified.


I2C Interview Questions 32 & 33

How do you calculate the bit rate for I2C communication?

Bit Rate (BR)=Tbit1

Where:

Tbit is the duration of one bit in seconds.

The calculation involves determining the desired bit rate and then finding the reciprocal of the bit time (Tbit) to obtain the actual bit rate.

Here are the steps to calculate the bit rate for I2C communication:


What is the role of the Acknowledge bit in I2C communication?

Aspect Description
Function – Confirms the successful reception of data by the receiver.
  – Facilitates multi-byte data transmission by signaling the readiness of the receiver for the next byte.
Signaling Acknowledgment – Receiver pulls the Serial Data (SDA) line low during the Acknowledge bit time to acknowledge successful data reception (ACK).
  – If the receiver does not acknowledge or is not ready for more data, it lets the SDA line remain high (NACK).
Multi-Byte Transmission – Essential for multi-byte data transmission. After each byte, the sender expects acknowledgment or non-acknowledgment from the receiver.
  – Allows the sender to continue or conclude data transmission based on the receiver’s response.
End of Data Transmission – Signals the end of data transmission. After the last byte, the sender expects acknowledgment from the receiver.
Error Detection – Serves as a mechanism for error detection. If the receiver cannot correctly interpret the data, it may respond with a NACK, indicating a potential error.
Role in I2C Protocol – Integral part of the I2C protocol, ensuring reliable and controlled communication between master and slave devices.

I2C Interview Questions 34 to 36

Explain the concept of clock stretching in I2C and its significance.

Aspect Description
Concept of Clock Stretching  – Definition: Clock stretching is a mechanism in I2C where a slave device temporarily holds the Serial Clock (SCL) line low, extending the clock period.
– Controlled by Slaves: Slaves can stretch the clock when they need additional time to process data or perform internal operations.
Significance    – Synchronization: Allows slave devices to synchronize with the master’s clock, ensuring proper timing for data reception or transmission.
– Flexibility for Slaves: Gives flexibility to slower slave devices, enabling them to keep pace with the master’s clock without introducing errors.
– Prevents Data Corruption: Helps prevent data corruption by allowing slower devices to complete their operations before the next clock edge.
– Enhances System Robustness: Enhances the overall robustness of the I2C bus, accommodating variations in processing times among different devices.
Handling in Master Devices   – Wait for SCL to Go High: The master device waits for the SCL line to go high, indicating that the slave has released control of the clock.
– Detecting Clock Stretching: The master detects clock stretching by monitoring the SCL line during the clock period.
– Resumes Communication: Once clock stretching is resolved, the master resumes communication as usual.
Handling in Slave Devices   – Triggered as Needed: Slaves trigger clock stretching when additional processing time is required.
– Release Control After Processing: Slaves release control of the SCL line once the required processing is completed.
– Maintains Synchronization: Ensures that the slave and master devices stay synchronized during the communication sequence.


What is the role of the bus capacitance in I2C communication?


Explain the difference between I2C and SMBus.


I2C Interview Questions 37 to 45

What is I2C?

I2C is Inter Interconnected Circuited


Who developed the i2c communication protocol?

I2C is developed by  Philips (Now NXP Semiconductor).


I2C is half duplex or full duplex?

I2C is Half Duplex. Because this I2C communication can’t able to master send data to slave or slave send data to master in same time.


I2C is Synchronous or Asynchronous Communication?

Synchronous Communication, Because Master generate the clock signal and slave synchronous with the master clock signal. so this i2c communication is synchronous communication


I2C is a Serial or Parallel communication?

I2C is serial communication. required one data line for transmit all byte of data to the destination.


I2C is Edge Triggering or Level Triggering?

I2C is Level Triggering.


How many line required for I2C communication bus?

Two lines required for I2C Communication. That are SCL and SDA.


What is mean by SDA line in I2C communication bus?

SDA – Serial DAta line


What is mean by SCL line in I2C communication bus?

SCL – Serial CLock Line


I2C Interview Questions 46 to 50

Why required Pull up resistor connection for I2C?

System Bus lines are SCL and SDA are designed by Open drain logic, So required pullup resistor for making SDA & SCL line as high/low.


How you select I2C Pull up resistor?

Based on the i2c bus operating speed can be select the pull up resistor

  • Its Depends up on the Bus capacitance.
  • 2Kohm for 100Kbps
  • 10Kohm for 400Kbps


What are the i2c communication speed modes ?

Slow mode, Standard mode, Fast mode, Fast plus mode, Ultra fast mode.


How to set i2c speed in Master device?

Some device have default speed rate. most of the embedded micro-controllers support the standard mode(sm) 100kbs, fast mode(fm) 400kbs, fast mode plus (fm+) 1.2kbs, High speed mode(hs-mode) 3.4kbs.

  • ESP8266
    • ESP8266 I2C Supports two different speed mode, standard mode(sm) 100kbs, fast mode(fm) 400kbs, for more see this
    • ESP8266 NodeMCU platform I2C Supports only standard mode(sm) 100kbs. for more see this
  • Arduino I2C you can use function to set Wire.setClock(Speed_value) , I2C slave devices have no minimum working clock frequency, however 100KHz is usually the baseline. clockFrequency: the value (in Hertz) of desired communication clock. Accepted values are 100000 (standard mode) and 400000 (fast mode). Some processors also support 10000 (low speed mode), 1000000 (fast mode plus) and 3400000 (high speed mode). Please refer to the specific processor documentation to make sure the desired mode is supported. for more See this
  • For more see this


How to set i2c speed in Slave device?

  • We can’t able to set slave speed. because i2c master generates the clock signal. Slave device only sync with master clock
  • Single slave supports various operating speeds
    • Microchip MCP23008 supports 100kHz, 400kHz, 1.7MHz.
    • Microchip MCP23017 supports 100kHz, 400kHz, 1.7MHz.


I2C Interview Questions 51 to 54

What are the different addressing modes are available for i2c communication

  • Two different addressing modes are available for i2c communication.
    • 7-bit addressing
    • 8-bit addressing


How to set the address of the slave in I2C communication?

By selecting the hardware address lines in slave. make high or low in the hardware level, its depends up on the salve manufactures


I2C Master can communicate in same bus with one 7bit address slave and another 10bit address slave ?

Maximum length of the I2C Cable can use?

I was working up-to 3 meters RJ45 cable(LAN cable).


Advantages and disadvantages of I2C?

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C Quiz and Interview Questions
Embedded Interview Questions
I2C Interview Question
UART Interview Questions
SPI Interview Questions
ESP8266 Resource
MQTT Interview Questions
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