SPRADL9 February   2025 CC1310

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Sensor Controller in Building Automation
    2. 1.2 TI Devices
      1. 1.2.1 CC13x4 Wireless MCUs
      2. 1.2.2 CC26xx Wireless MCUs
  5. 2Sensor Controller
    1. 2.1 Features
    2. 2.2 Sensor Controller Power Modes
      1. 2.2.1 Active Mode
      2. 2.2.2 Low Power Mode
      3. 2.2.3 Standby Mode
      4. 2.2.4 Switching Between Power Modes
        1. 2.2.4.1 24MHz - Startup From Standby and Return to Standby Energy
        2. 2.2.4.2 2MHz - Startup From Standby and Return to Standby Energy
    3. 2.3 Power Measurement Setup
      1. 2.3.1 EnergyTrace™ Software
      2. 2.3.2 Software
      3. 2.3.3 Current Consumption Measurements
      4. 2.3.4 Hardware
  6. 3Building Automation Use-Cases and Techniques using Sensor Controller
    1. 3.1 PIR Motion Detection
      1. 3.1.1 PIR Traditional Signal-Chain
      2. 3.1.2 Capacitor-less Motion Detection Block Diagram
      3. 3.1.3 Digital Signal Processing
        1. 3.1.3.1 Hardware
        2. 3.1.3.2 Digital Signal Processing
    2. 3.2 Glass Break Detection
      1. 3.2.1 Low-Powered and Low-Cost Glass Break Block Diagram
    3. 3.3 Door and Window Sensor
    4. 3.4 Low-Power ADC
      1. 3.4.1 Code Implementation in Sensor Controller Studio
      2. 3.4.2 Measurements
    5. 3.5 Different Sensor Readings with BOOSTXL-ULPSENSE
      1. 3.5.1 Capacitive Touch
      2. 3.5.2 Analog Light Sensor
      3. 3.5.3 Potentiometer (0 to 200kΩ range)
      4. 3.5.4 Ultra-Low Power SPI Accelerometer
      5. 3.5.5 Reed Switch
  7. 4Summary
  8. 5References

3.5.1 Capacitive Touch

As smart buildings and IoT-driven infrastructures gain traction, CapTouch offers an intuitive interface for controlling a wide range of systems such as lighting, HVAC and access control. For instance, in lighting control applications, CapTouch panels allow users to adjust brightness or schedule lighting changes with simple taps. In HVAC systems, CapTouch interfaces replace traditional thermostats with touchscreens that provide control over temperature, humidity and air quality settings. They can also be found in access control applications integrated into touch-sensitive keypads and biometric devices utilized for secure entry.

The Capacitive touch example on the BOOSTXL-ULPSENSE uses a small circular copper area on the top layer and a hatched ground plane on the bottom layer to create a small capacitor. The Sensor Controller is able to measure the capacitance using the ISRC (current source) and time-to-digital converter (TDC) peripherals. The capacitance of the system can change when touched with a finger tip. The capacitive touch example is tested both without any input to the cap touch buttons, and with the buttons activated. When no touch is detected on the buttons, the Sensor Controller wakes up with a frequency of 32Hz. If a button press is detected, the Sensor Controller increases the wake-up interval to around 100Hz. The Sensor Controller can also wake up the System CPU and notify of the touch event.

Capacitive Touch Principle (Simplified)Figure 3-13 Capacitive Touch Principle (Simplified)
Table 3-3 Capacitive Touch Power Consumption
Average Current ConsumptionUnitBattery life (CR123)
Without Touch (32Hz)8.5µA2 years and 8 months
With Touch (approximately 100Hz)84.1µA3 months

The following images show the current signal captured by EnergyTrace™ over the measurement period of 1 second as well as a single measurement.

Capacitive Touch: Measurement Without Touch - 1 SecondFigure 3-14 Capacitive Touch: Measurement Without Touch - 1 Second
Capacitive Touch: Measurement Without Touch - One MeasurementFigure 3-15 Capacitive Touch: Measurement Without Touch - One Measurement
Capacitive Touch: Measurement With Touch - 1 SecondFigure 3-16 Capacitive Touch: Measurement With Touch - 1 Second
Capacitive Touch: Measurement With Touch - One MeasurementFigure 3-17 Capacitive Touch: Measurement With Touch - One Measurement

The 1 second measurement window shows the increased wake-up frequency described before with each spike (One measurement) representing a wake-up of the Sensor Controller.