Embedded Systems: CMPE 30247 Module 4 Reviewer

Flashcards covering key concepts from the lecture notes, focusing on serial communication protocols, wireless technologies, and data acquisition in embedded systems.

Communication in Embedded Systems

Data is transferred in bits, following predefined rules.

Parallel Communication

Transmits multiple bits simultaneously over separate lines. Faster but more costly and less suitable for long distances.

Serial Communication

Transmits data one bit at a time over a single line. Less costly, better for long distances, and more resistant to noise.

UART (Universal Asynchronous Receiver-Transmitter)

Facilitates communication between two devices by converting parallel data to serial and vice versa.

UART Data Packets

Data is sent in packets that include a start bit, the data bits, a parity bit, and a stop bit.

Baud Rate

The speed of data transfer in UART; both UARTs must be set to the same rate.

SPI (Serial Peripheral Interface)

A synchronous protocol known for its high-speed, uninterrupted data transfer using a master-slave architecture

MOSI (Master Out Slave In)

Master sends data to the slave in SPI.

MISO (Master In Slave Out)

Slave sends data to the master in SPI.

SCLK (Serial Clock)

Clock signal generated by the master in SPI to synchronize data transfer.

SS/CS (Slave Select/Chip Select)

Master uses this line in SPI to select the slave it wants to communicate with.

I2C (Inter-Integrated Circuit)

A versatile protocol that combines features of both SPI and UART, ideal for connecting multiple devices on a single bus with multiple masters and slaves.

SDA (Serial Data)

Used for both sending and receiving data in I2C.

SCL (Serial Clock)

The clock line that synchronizes the system in I2C.

Wi-Fi

Internet access in homes, offices, and public spaces.

Bluetooth

Wireless audio, peripherals (keyboards, mice), and data transfer.

Zigbee

Home automation (smart lighting, thermostats).

Sensor Data Acquisition

The process of collecting physical data (temperature, motion, etc.) using sensors.

Analog to Digital Conversion (ADC)

Sensors produce analog signals, which must be converted to digital signals for processing by microcontrollers.

Sampling

Taking periodic snapshots of the analog signal.

Quantization

Assigning a digital value to each sample.

Filtering

Removes noise to improve signal quality.

Calibration

Ensures sensor output is accurate.

Normalization

Scales data to a specific range.

Error Detection and Correction

Techniques used to ensure data integrity and reliability during communication.

Parity Bit

Adding extra bits to a data stream to detect errors; parity can be even or odd.

Checksum

A method of error detection where a checksum is calculated and appended to the data.

Cyclic Redundancy Check (CRC)

A more advanced error detection technique that can also correct errors by using polynomial division.

Flow Control

Ensuring data is sent in the correct order and that no data is lost during transmission.

Hardware Flow Control

Hardware signals to pause and resume data transmission. (e.g., RTS/CTS)

Software Flow Control

Using specific control characters to manage data flow. (e.g., XON/XOFF)

Data Encryption

Preventing unauthorized access to transmitted data.

Encryption

Converting data into a coded form using a key.

Decryption

Converting encrypted data back into its original form using the correct key.

Wi-Fi Protected Access (WPA)

Securing wireless communication using encryption protocols.

Sensor Accuracy

Ensuring accurate data capture and conversion from analog sensors.

Sensor Repeatability

Consistency of sensor readings over time.

Sensor Resolution

The smallest change a sensor can detect.

Sensor Response Time

The delay between a change in the physical quantity and the sensor's output.

RTOS (Real-Time Operating System)

A real-time operating system (RTOS) is an operating system that guarantees processing within specific time constraints, crucial for time-sensitive embedded applications.

Preemptive Scheduling

A preemptive scheduler can interrupt a currently running task to execute a higher-priority task, essential for meeting deadlines in RTOS.

Non-Preemptive Scheduling

A non-preemptive scheduler allows a task to run until completion, which may cause delays for higher-priority tasks in RTOS.

Semaphore

A semaphore is a signaling mechanism used to control access to shared resources, preventing race conditions in multithreaded RTOS environments.

Mutex

A mutex (mutual exclusion) is a locking mechanism that ensures only one task can access a shared resource at a time, avoiding conflicts in RTOS.

Priority Inversion

Priority inversion occurs when a high-priority task is forced to wait for a lower-priority task to release a resource, which can be mitigated using priority inheritance.

Interrupts

Interrupts are hardware-generated signals that cause the CPU to immediately suspend the current task and execute a specific interrupt service routine (ISR).

ISR (Interrupt Service Routine)

An Interrupt Service Routine (ISR) is a software routine that handles specific interrupt requests, typically requiring fast execution to avoid delaying other tasks.

Watchdog Timer

Watchdog timers are used to detect and recover from system failures by resetting the system if a predefined time interval elapses without being refreshed.

Power Management

Power management techniques extend battery life by reducing power consumption through methods like sleep modes, dynamic voltage scaling, and clock gating.

Sleep Modes

Sleep modes reduce power consumption by turning off non-essential components while preserving system state, quickly resuming operation when needed.

DVFS (Dynamic Voltage and Frequency Scaling)

Dynamic Voltage and Frequency Scaling adjusts voltage and frequency based on workload to minimize power consumption while maintaining performance.