TIDUFK2 September   2026

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Processing
      2. 2.2.2 Voltage and Current Sensing
        1. 2.2.2.1 Voltage Measurement
        2. 2.2.2.2 Current Measurement
      3. 2.2.3 Solenoid – Relay Driver
      4. 2.2.4 Temperature Measurement
    3. 2.3 Highlighted Products
      1. 2.3.1 CC2340R53
      2. 2.3.2 OPA2323
      3. 2.3.3 DRV8213
      4. 2.3.4 TMP236A2
  9. 3System Design Theory
    1. 3.1 Software Architecture
      1. 3.1.1 System Initialization
      2. 3.1.2 Sample Acquisition
      3. 3.1.3 Sample Processing and Task Prioritization
    2. 3.2 Circuit Breaker Functionality
      1. 3.2.1 Breaker State and Relay Control
      2. 3.2.2 Instantaneous Short-Circuit Trip
      3. 3.2.3 Inverse-Time Overload Trip
    3. 3.3 Electrical Metrology
    4. 3.4 Zigbee Connectivity
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 Hardware Connections and Test Points
    2. 4.2 Test Setup
      1. 4.2.1 Connecting the TIDA-011030 to the Metering Test Equipment
      2. 4.2.2 Power-Supply Options
      3. 4.2.3 Metrology Calibration
      4. 4.2.4 Test-Data Acquisition and Error Calculation
    3. 4.3 Test Results
      1. 4.3.1 Relay Control and Protection
        1. 4.3.1.1 Relay Pull-In and Holding PWM
        2. 4.3.1.2 Instantaneous Trip and Relay-Opening Latency
        3. 4.3.1.3 Inverse-Time Overload Trip
      2. 4.3.2 Metering
      3. 4.3.3 Real-Time Software Performance
      4. 4.3.4 Zigbee Functional Test
  11. 5Design and Documentation Support
    1. 5.1 Tools and Software
      1. 5.1.1 Tools
      2. 5.1.2 Software
    2. 5.2 Documentation Support
    3.     Trademarks
  12. 6About the Author

3.2.1 Breaker State and Relay Control

The breaker control is implemented as a state machine with the three states listed in Table 3-2.

Table 3-2 Circuit Breaker States
State Relay command Status indication
OPEN De-energized Open - Blue LED
CLOSED Energized Closed - Green LED
TRIPPED De-energized Trip - Red LED

After reset, the breaker always enters the OPEN state. The relay driver is disabled, the open LED is activated, and no current can intentionally flow through the load path. This provides a defined hardware-safe startup condition independent of the previously commanded Zigbee state.

A short press of the local button toggles the requested breaker state. Zigbee On/Off commands explicitly request either an open or closed state. Both interfaces write to a common control mailbox, and the most recently received normal control command is processed by the Protection task.

Protection events have priority over all user commands. When an instantaneous-current, ADC window-comparator, or overload trip occurs, the breaker:

  1. Changes to the TRIPPED state
  2. Stores the corresponding trip reason
  3. Discards any pending close request
  4. De-energizes the relay driver
  5. Activates the red trip LED

The trip state remains latched until a new explicit open or close command is processed. An open command clears the trip indication and places the breaker in the OPEN state. A close command resets the trip state and attempts to energize the relay again.

The relay is controlled through the DRV8213. To close the breaker, the PWM output is prepared before IN1 is enabled. The coil then receives full drive for 100ms. This interval is monitored using a timestamp without blocking the Protection task. Afterwards, the driver changes to a 20kHz holding waveform with 35% effective coil drive, corresponding to IN2 being low for 35% and high for 65% of each PWM period.

Opening or tripping clears IN1 immediately and subsequently stops the PWM output. A protection trip can initiate this sequence directly from the ADC interrupt path. If the relay driver cannot be prepared successfully, the close operation is aborted and the breaker remains OPEN.