SPI is a synchronous serial communication protocol. Transitioning to potential interview questions related to SPI, here are some topics you might encounter:
Contents
SPI Interview Questions 01 to 07
What is the abbreviation of SPI? or What does SPI mean? Or what is the acronym SPI?
Serial Peripheral interface
What is SPI?
Serial Peripheral Interface, SPI is a wired serial communication protocol. its a single master communicate with multi slave protocol and it’s synchronous full duplex communication.
How does it differ from other communication protocols?
Comparison with other communication protocols like I2C and UART.
Describe the basic architecture of an SPI communication system.
What is the role of the SS/CS line in SPI communication?
How the Slave Select/Chip Select line is used to enable/disable slave devices.
Explain the difference between half-duplex and full-duplex communication. How does SPI support full-duplex communication?
What is the role of the Serial Clock (SCLK) in SPI?
Explanation of how the clock signal is used to synchronize data transmission between the master and slave devices.
SPI Interview Questions 08 to 15
How the data typically transferred in SPI?
Discussion of the shift register mechanism and how bits are shifted in and out during data transmission.
What is the significance of the MOSI and MISO lines in SPI?
Explanation of MOSI (Master Out Slave In) for data transmission from master to slave and MISO (Master In Slave Out) for data transmission from slave to master.
In SPI, the system determines the data transfer rate by configuring the clock frequency?
Explain the concept of SPI daisy chaining ?
Description of connecting multiple slave devices in a series on the same SPI bus
What are the Advantages and disadvantages of SPI?
Discussion of pros and cons, such as simplicity, speed, and hardware requirements.
Is serial or parallel communication?
SPI is serial communication. By serially send and receive data in same line.
synchronous or synchronous communication?
SPI is synchronous communication because of master generate clock signal its sync with slave.
Is it a half duplex or full duplex?
SPI is full duplex communication because SPI slave and master can communicate each other in same time.
SPI Interview Questions 15 to 21
How many wires/lines required for SPI communication?
Genrally required 4 wires for SPI communication and wires may be required additionally one(SS-Slave select) It’s depends upon the number of slave communicate with master.
What are signal wire name of SPI communication?
SCK, MOSI, MISO, CS
What is SCK wire in SPI?
SCK – Serial Clock Signal
What is MOSI wire in SPI?
MOSI – Master Out Slave In
What is MISO wire in SPI?
MISO – Master In Slave Out
What is CS/SS wire in SPI?
CS -Chip Select
What is the speed of SPI?
SPI works up to 10Mhz speed. Compare to other wired communication protocol, SPI is much faster.
SPI Interview Questions 22
Does SPI need a baud rate?
The term 'baud rate' is typically associated with asynchronous communication protocols like UART, where it represents the number of signal changes per second. However, in the context of SPI (Serial Peripheral Interface), the concept differs. Instead of a baud rate, SPI relies on a clock signal (SCLK) to synchronize data transfer between the master and slave devices.
In SPI communication, the clock frequency (measured in Hertz) determines the rate at which bits are shifted between devices. Generated by the master device, both the master and slave(s) must operate at compatible clock frequencies.
Although SPI doesn't use the term 'baud rate,' the clock frequency concept is analogous—higher clock frequencies facilitate faster data transfer. The clock frequency, specified in the SPI configuration and set by the master device, is a crucial parameter, determining the speed of data transfer on the bus.
In summary, while SPI doesn't employ the term 'baud rate,' the clock frequency serves a similar purpose, defining the rate of data transfer between devices. When working with SPI, you'll configure the clock frequency instead of a baud rate. It's essential to ensure that all devices on the SPI bus can handle the selected clock frequency for reliable communication.
SPI Interview Questions 23
What is the minimum Speed of SPI?
The minimum speed of SPI (Serial Peripheral Interface) is not strictly defined by the protocol itself, but rather by the limitations of the devices involved and the implementation in a particular system.
In SPI, the communication speed is determined by the clock signal (SCLK) frequency, which is set by the master device. SPI devices are designed to operate over a range of clock frequencies, and this range is usually specified in the datasheet for each device. The minimum speed is, therefore, dependent on the capabilities of the specific SPI devices being used in the communication.
Some SPI devices might have a specified minimum clock frequency for proper operation, while others may be more flexible. It’s essential to refer to the datasheets of the SPI master and slave devices in your specific application to determine the acceptable range of clock frequencies.
In practice, the minimum SPI speed is often constrained by factors such as the setup and hold times of the devices, the capacitance of the communication lines, and the electrical characteristics of the hardware. Always refer to the documentation provided by the manufacturers of the SPI devices to ensure proper and reliable operation within the specified speed range
SPI Interview Questions 24 to 26
What is the maximum speed of SPI?
Maximum Speed of SPI is 10Mhz
Which device (Master/slave) generates clock signal in SPI?
SPI master only generate clock signal. SPI Slave device function is should sync with SPI master clock.
How to set SPI bus speed in master device?
Setting the SPI bus speed in a master device involves configuring the clock frequency (SCLK) at which the master and slave devices will communicate. The process may vary depending on the specific microcontroller or microprocessor you are using, as each has its own set of registers or functions for SPI configuration.
Important Note:
is i2c or SPI faster?
SPI is always faster then I2C Communication. Because SPI maximum speed supports 10Mhz, But I2C maximum speed supports 5Mhz
SPI Interview Questions 27 to 29
In the SPI System, how many slaves can connect?
- The maximum number of devices to connect depends on two conditions.
- Depends on several slave select lines on the hardware, i.e., if my SPI master has 4 slave select lines then we can connect 4 slaves normally which we do for chip select in peripherals.
- Depending on fan-out of the pin, fan-out is nothing but the maximum number of possible devices that can be connected to the pin
- The number of SPI slaves is not limited. But at the same time, it is restricted according to the number of hardware pins of the controller. You can add digital muxes (multiplexors) and control more slave devices than you have digital pins on the controller. However, the SPI was designed for communication over short distances within a box. So, the physical size of the bus can become a problem (bus capacitance, EMI).
What will happen if two SPI slaves same time communicate with the Master (two Cs pins are high)?
- Contention on MISO/MOSI Lines
- Collision on SS/CS Lines
- Clock Synchronization Issues
- Incomplete Transactions
- Bus Contentions and Signal Integrity
SPI Interview Questions 30
What are the limitations of SPI interface?
| Data Logging | Use Case: Collecting sensor data from IoT devices and sending it to a web server for logging. |
| Example: Temperature and humidity readings from a sensor sent periodically to a server for historical tracking. | |
| Remote Control | Use Case: Controlling devices remotely through a web interface. |
| Example: Sending commands to turn on/off lights, appliances, or actuators. | |
| Sensor Data Transmission | Use Case: Transmitting real-time sensor data to a central server. |
| Example: Accelerometer data from a wearable device sent to a cloud server for analysis. | |
| Form Submissions | Use Case: Submitting form data from a device to a web server. |
| Example: User input from a device form (e.g., a weather station) sent to a server for processing. | |
| User Authentication | Use Case: Authenticating users and transmitting login credentials securely. |
| Example: Transmitting username and password securely to a server for authentication. | |
| Integration with APIs | Use Case: Interacting with third-party APIs or services. |
| Example: Sending data to a cloud service API for weather information or other integrations. | |
| Alerts and Notifications | Use Case: Sending alerts or notifications from a device to a central server. |
| Example: Sending an alert when a predefined threshold is exceeded (e.g., temperature too high). | |
| Configuration Updates | Use Case: Updating device configurations remotely. |
| Example: Sending configuration parameters to a device, allowing dynamic adjustments. | |
| Data Synchronization | Use Case: Synchronizing data between devices and servers. |
| Example: Uploading data collected offline on a device to a central server when connectivity is restored. | |
| Command and Control Systems | Use Case: Building command and control systems for industrial or automation applications. |
| Example: Controlling and monitoring devices in a manufacturing plant through a central server. |
SPI Interview Questions 31 to 33
Enabling mode fault in SPI results in the system experiencing certain consequences.
Enabling mode fault detection is particularly useful in systems where SPI devices may be dynamically connected or configured. It helps to catch issues early on and provides a means for the system to respond appropriately to ensure reliable communication.
It's important to note that the specific implementation details, features, and terminology may vary between different microcontrollers, microprocessors, or SPI peripheral devices. Always refer to the documentation provided by the manufacturer for accurate and detailed information regarding mode fault detection in a particular SPI implementation.
What are the hardware main part of the SPI?
- Status,
- Control,
- Data register,
- Shifted logic,
- Baud rate generator,
- Master/slave control logic,
- Port control logic
Can SPI slave generate a clock signal?
No. SPI slave function is should synchronize with SPI master clock