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Questions and Answers
Which statement describes the I2C protocol?
Which statement describes the I2C protocol?
In I2C, both SDA and SCL lines are in LOW state when the bus is inactive.
In I2C, both SDA and SCL lines are in LOW state when the bus is inactive.
False
What are the two special signals in I2C communication?
What are the two special signals in I2C communication?
START condition and STOP condition
The I2C protocol uses _____ lines for communication: SDA and SCL.
The I2C protocol uses _____ lines for communication: SDA and SCL.
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Match the following I2C modes with their descriptions:
Match the following I2C modes with their descriptions:
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What must a slave device do after receiving a byte from the master?
What must a slave device do after receiving a byte from the master?
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In I2C, each device on the bus has a unique 8-bit address.
In I2C, each device on the bus has a unique 8-bit address.
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In I2C communication, what does the R/W bit indicate?
In I2C communication, what does the R/W bit indicate?
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What is the default baud rate used by Cisco routers for UART communication?
What is the default baud rate used by Cisco routers for UART communication?
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The 1-Wire interface can communicate at speeds up to 160kbit/s only in its regular mode.
The 1-Wire interface can communicate at speeds up to 160kbit/s only in its regular mode.
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What does the '8N1' configuration in UART communication represent?
What does the '8N1' configuration in UART communication represent?
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In the 1-Wire interface, the master device initiates communication by pulling the wire to the _____ level.
In the 1-Wire interface, the master device initiates communication by pulling the wire to the _____ level.
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Match the following communication interfaces with their characteristics:
Match the following communication interfaces with their characteristics:
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Which of the following is NOT a characteristic of the USB interface?
Which of the following is NOT a characteristic of the USB interface?
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In the 1-Wire protocol, the idle state of the wire is '0'.
In the 1-Wire protocol, the idle state of the wire is '0'.
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What is the purpose of the pull-up resistor in the 1-Wire interface?
What is the purpose of the pull-up resistor in the 1-Wire interface?
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Which of the following is a method of data transmission that uses electrical or optical pulses without modulation?
Which of the following is a method of data transmission that uses electrical or optical pulses without modulation?
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In Unipolar NRZ coding, the bit '0' state is represented by a negative physical state.
In Unipolar NRZ coding, the bit '0' state is represented by a negative physical state.
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What is the advantage of Polar RZ coding compared to Unipolar RZ coding?
What is the advantage of Polar RZ coding compared to Unipolar RZ coding?
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A _____ interface technology allows communication with a single wire, reducing the number of connections needed for data transmission.
A _____ interface technology allows communication with a single wire, reducing the number of connections needed for data transmission.
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Match the coding techniques with their descriptions:
Match the coding techniques with their descriptions:
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What is a common problem encountered with Unipolar RZ coding?
What is a common problem encountered with Unipolar RZ coding?
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Baseband transmission can use multiple bits to be written or read simultaneously.
Baseband transmission can use multiple bits to be written or read simultaneously.
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What is the main feature of the Return-to-Zero (RZ) technique?
What is the main feature of the Return-to-Zero (RZ) technique?
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Study Notes
UART
- Widely used for terminal applications, such as Cisco routers.
- Default settings are 9600bps and 8N1.
1-Wire Interface
- Developed by Dallas Semiconductors.
- Uses two wires: communication line and ground.
- Communication line provides power to slave devices.
- Each device connects with an open-drain output and pull-up resistor.
- Allows any device to pull the wire to "0".
- Each device can monitor the wire's state.
- Relatively slow (16.3kbit/s, but can reach 160kbit/s in "burst" mode).
- Supports long wire lengths (~100m).
1-Wire Interface Communication
- Wire idle state is "1".
- Master device initiates data transfer by pulling the wire to "0" for at least 480us.
- This action resets all slave devices.
- Slave devices send a "presence" signal by pulling the wire to "0" for 60us.
1-Wire Interface Protocol
- Master pulls the wire to "0" for data transmission:
- 1-15us for "1" logical value.
- 60us for "0" logical value.
- To read data, master sends a short pulse (1-15us).
- Slave pulls down the line for "0" (60us).
- Slave does nothing for "1".
- Basic sequence includes a reset pulse, 8 bits of command, and a data byte.
- Supports multiple slaves, each with a unique 64-bit ID.
Universal Serial Bus (USB)
- Standardized serial bus for computer-peripheral communication and power supply.
- Full-duplex communication, supporting various speeds (USB 2.0, USB 3.0, etc.).
- Provides power to devices (5V DC, 0.5A or 0.9A).
- Offers high-speed data transfer, wide adoption, and plug-and-play functionality.
- More complex than SPI, I2C, UART.
- Not suitable for IC-to-IC communication.
I2C (Inter-Integrated Circuit)
- Developed by Philips, synchronous serial, half-duplex, multi-master, multi-slave protocol.
- Uses two bidirectional lines: SDA (Serial Data Line) and SCL (Serial Clock Line).
- Employs device addresses for communication with multiple devices instead of individual slave select signals.
- Advantages: Fewer wires, supports multiple devices on the same bus.
- Disadvantages: Slower than SPI (originally limited to 100kbit/s and 400kbit/s, but faster speeds up to 5Mbit/s are available).
- More complex due to addressing and half-duplex communication.
I2C Design
- Each device has a 7-bit address (10-bit addresses also available).
- Allows multiple master devices to control the bus.
- All target (slave) nodes listen to communication but only respond at their respective addresses.
- Four modes:
- Master transmit: Controller sending data to a slave.
- Master receive: Controller receiving data from a slave.
- Slave transmit: Slave sending data to the controller.
- Slave receive: Slave receiving data from the controller.
I2C Signals
- Signal levels assigned to "1" and "0" bits.
- Both SDA and SCL lines are HIGH in the inactive state.
- SDA is examined after the SCL rises HIGH.
- Two special signals:
- START condition: SDA pulled LOW while SCL remains HIGH.
- STOP condition: SDA pulled HIGH while SCL remains HIGH.
- After the START condition, master starts transmitting data to slaves.
- First data byte contains the slave device address and a R/W bit.
I2C Communication
- Master sends START condition, address, and R/W bits.
- When master writes to the slave, the slave generates an ACK or NAK bit after receiving a byte.
- Master provides an extra clock for the ACK/NAK bit.
- For master reading from the slave, the master generates an ACK or NAK bit after receiving a byte.
- Master can generate a START condition during transmission, known as REPEATED START condition.
Overview of Digital Interfaces
- Handling binary values requires multiple bits for simultaneous writing or reading.
- Multiple bits require multiple pins and wires.
- These wires form a "bus".
- A processing unit communicates with other units on the bus.
- Bus can be serial or parallel.
Transmission Techniques
- Two main methods:
- Baseband: Converting data bits into electrical or optical pulses without modulation.
- Broadband: Modulating the carrier signal's frequency, amplitude, or phase based on data bits.
Baseband
- Two main techniques:
- Return-to-Zero (RZ): Signal's amplitude returns to zero within the symbol period.
- Non-Return-to-Zero (NRZ): Signal's amplitude doesn't return to zero within the symbol period.
- Assign physical states to logical states (e.g., 5V represents logical "1").
- The other logical state is represented by 0V (unipolar coding) or a negative value (bipolar coding).
- Challenge: Synchronizing bitrate clocks between the source and destination.
Unipolar RZ Coding
- Bit "1" is represented by "+A" physical state (+1V in the example).
- Bit "0" is represented by 0V.
- Physical state returns to 0V in the middle of the symbol period.
- Problem: Data containing only "0" bits results in a permanent 0V physical state, making clock synchronization impossible.
Polar RZ Coding
- Bit "1" is represented by "+A" physical state (+1V in the example).
- Bit "0" is represented by "-A" physical state (-1V in the example).
- Physical state returns to 0V in the middle of the symbol period.
- Advantage: Line state changes with each bit, facilitating relatively easy synchronization.
Unipolar NRZ Coding
- Bit "1" is represented by "+A" physical state (+1V in the example).
- Bit "0" is represented by 0V.
- Problem: No physical state change occurs if payload data contains only "1" or "0" bits.
Polar NRZ Coding
- Bit "1" is represented by "+A" physical state (+1V in the example).
- Bit "0" is represented by "-A" physical state (-1V in the example).
- Advantage: Line state changes with each bit, facilitating relatively easy synchronization.
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Description
Test your knowledge on UART and 1-Wire interface applications and communication protocols. This quiz covers default settings, data transfer mechanisms, and protocol specifics for these important interfaces used in electronics. Perfect for those studying computer engineering or electronics!
