2.2 Analog and Digital Sensors

Sensors are the eyes and ears of IoT systems, capturing real-world data. Analog sensors provide continuous measurements, while digital sensors offer discrete outputs. Understanding their differences is crucial for selecting the right sensor for your IoT application.

Data processing and communication protocols are the backbone of IoT sensor integration. Analog-to-digital conversion transforms analog signals into digital data, while protocols like I2C and SPI enable efficient communication between sensors and microcontrollers in IoT devices.

Sensor Types and Data Acquisition

Analog vs digital sensors

Top images from around the web for Analog vs digital sensors

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  Karan Tanna || Week 11 View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

1 of 3

Top images from around the web for Analog vs digital sensors

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  Karan Tanna || Week 11 View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

• 

  0.- Analógico vs Digital View original

  Is this image relevant?

1 of 3

• Analog sensors produce continuous, varying voltage signals proportional to the measured physical quantity (temperature, pressure, light intensity)
• Digital sensors generate discrete, binary signals represented as a series of 0s and 1s indicating the presence or absence of a specific condition (motion detection, humidity threshold, acceleration)

Sensor types in IoT applications

• Analog sensors
  • Advantages
    • Provide precise, high-resolution data suitable for measuring continuous phenomena (temperature gradients, pressure changes)
    • Offer a wide range of values allowing for detailed analysis and control
  • Disadvantages
    • Require additional circuitry for signal conditioning (amplification, filtering) and analog-to-digital conversion
    • More susceptible to noise and interference from external sources (electromagnetic fields, power line noise)
• Digital sensors
  • Advantages
    • Directly compatible with digital systems and microcontrollers simplifying integration and data processing
    • Less susceptible to noise and interference due to binary nature of the output signal
    • Easier to interface and process data using standard communication protocols (I2C, SPI)
  • Disadvantages
    • Lower resolution compared to analog sensors limiting the level of detail in the measured data
    • May require more complex communication protocols and timing considerations for reliable data transfer

Data Processing and Communication Protocols

Analog-to-digital conversion process

• Analog-to-digital conversion (ADC) transforms continuous analog signals into discrete digital values
  1. Sampling measures the analog signal at regular intervals determined by the sampling rate (samples per second)
  2. Quantization maps each sampled value to a corresponding digital value based on the ADC resolution (number of discrete levels)
  3. Encoding represents the quantized values as binary numbers for digital processing and storage
• Role in IoT data acquisition
  • Enables digital systems to process and interpret analog sensor data (converting temperature readings to digital values)
  • Allows for efficient storage, transmission, and analysis of sensor data in IoT networks and cloud platforms

Digital sensor communication protocols

• I2C (Inter-Integrated Circuit)
  • Two-wire, synchronous, multi-master, multi-slave protocol consisting of Serial Data Line (SDA) and Serial Clock Line (SCL)
  • Supports multiple devices on the same bus reducing wiring complexity (connecting multiple sensors to a single microcontroller)
  • Slower than SPI but requires fewer pins making it suitable for low-speed, low-pin-count applications
• SPI (Serial Peripheral Interface)
  • Four-wire, synchronous, single-master, multi-slave protocol consisting of Master Out Slave In (MOSI), Master In Slave Out (MISO), Serial Clock (SCLK), and Chip Select (CS) lines
  • Provides full-duplex communication allowing simultaneous data transmission and reception (sending commands and receiving sensor data)
  • Faster than I2C but requires more pins and dedicated CS lines for each slave device (connecting high-speed sensors like accelerometers)