Embedded Systems Sensors Overview

Input Block

• Sensors are essential components in embedded systems, capturing signals from the physical world.
  • Light Sensitive Sensors detect electromagnetic radiation, commonly using photodiodes, which are reverse-biased semiconductors.
  • Temperature Sensors provide feedback to control systems.
  • Line-tracking Sensors detect lines by detecting color differences using the TTL signal.
  • Ultrasonic Sensors measure distance using sound waves through a timing mechanism between transmission and reception.
  • Motion Sensors utilize electronic sensors to quantify motion and alert users of moving objects within their field of view.
  • Gas Sensors detect gas leaks using a sensitive ceramic component with AL2O3.
  • Hall Sensors are omnidirectional magnetic sensors used for proximity switching, positioning, speed detection, and current sensing.
  • Color Sensors detect and measure a wide range of visible colors.
  • Digital Tilt Sensors utilize either mercury-based or ball-based modules to indicate tilt.
  • Triple Axis Accelerometers measure acceleration and tilt angle.
  • Analog Sound Sensors use electret condenser microphones to convert sound energy into an electrical signal.
  • Voice Recognition converts spoken words into electrical signals and translates them into coded patterns with assigned meaning.
  • Vibration Sensors are spring-based sensors detecting vibration.
  • Flame Sensors detect flames by sensing specific wavelengths of light.
  • Capacitive Touch Sensors recognize the presence of objects due to their capacitive characteristics.
  • Image Sensors capture visual information.
    • CMOS Sensors have an architecture similar to standard memories, allowing random access and readout of individual pixels.
    • Charge-coupled Devices (CCDs) require transferring charges from one pixel to the next before readout.
  • Joystick Modules provide two analog outputs based on X and Y control, utilizing potentiometers and buttons.
  • Biometric Sensors employ various methods for authentication, including iris scans, fingerprint sensors, and facial recognition.
  • Radio-frequency Identification (RFID) tags consist of an integrated circuit and an antenna, providing identity to RFID readers.

Datapath Block and Control Block

• Datapath and Control Block are crucial for embedded systems, coordinating activities and performing data processing operations.
  • Datapath Communication involves information transfer through channels, with communication media facilitating the process. Media types include wireless, optical, and wired options.
  • Control Block encompasses processing units responsible for system operation.
    • Package Types
      • System-in-Package (SiP) integrates essential components on a single chip, ensuring functionality within an electronic sub-system.
      • Package-on-a-Package (PoP) stacks packages vertically via ball grid arrays, enhancing functionality.
      • System-on-a-Chip (SoC) integrates all computer components into a single chip, employing either microcontrollers or microprocessors as core components.
    • Processor Types
      • Very Long Instruction Word (VLIW) Processors execute multiple operations concurrently, encoding instructions into "instruction packets."
      • Explicit Parallelism Instruction Set Computer (EPIC) uses instructions that explicitly identify operations to be performed in parallel.
      • Multicore Processors integrate multiple cores on a single chip, enabling faster communication.
        • Homogeneous Multicore Architecture limits design effort and facilitates easy software migration.
        • Heterogeneous Multicore Architecture is ideal for specific applications and achieves optimal energy efficiency.
      • Graphics Processing Units (GPUs) prioritize concurrent computation for efficient performance.
      • Multiprocessor Systems-on-a-Chip (MPSoCs) combine heterogeneous multi-core systems with GPUs, incorporating additional system components on a single chip.

Memory Block

• Memory Blocks handle instructions and data movement, serving as short-term storage.
  • Memory Types
    • ROM (Read-Only Memory) stores embedded instructions and flash-programmable data.
    • RAM (Random Access Memory) provides volatile storage.
      • Processor Registers are high-speed registers directly controlled by the CPU.
      • Working Memory (Main Memory Ram) is the primary memory for storing programs and data.
      • Buffer Memory (Caches, Buffers, and scratchpad memory) assists in temporary storage for fast data access.

Output Block

• Output Block sends data and signals to the external world using actuators. Actuators are devices controlled by voltage, which can be converted using digital-to-analog converters (DACs).
  • Light-Emitting Diodes (LEDs) provide visual indication.
  • Motor Control involves applying torque to loads using motor windings.
    • DC Motors require drivers for torque control and utilize H-bridges, electronic circuits enabling bidirectional motor control.
    • Stepper Motors convert digital pulses into mechanical rotations, offering precise control and high torque.
    • Servo Motors consist of a motor, gearbox, position sensor, error amplifier, and driver circuit for position control.
      • Pulse Width Modulation (PWM) efficiently delivers power under digital control.