Blast gate servo controller for Arduino
See 3d printed parts at : https://www.thingiverse.com/thing:3301904
- Allows a single push button to switch between different blast gates, with only a single one open at a time
- Currently open blast gate is indicated by an LED
- Optional automatic control using AC current sensors to detect active tools
- Debug output support for troubleshooting
- Configurable servo positions for precise gate control
- Arduino Uno (R3 or R4)
- A servo for each blast gate (up to 5)
- One push button
- Optional: An LED for each blast gate
- Optional: AC current sensors from https://moderndevice.com/products/current-sensor
- Install Visual Studio Code
- Install PlatformIO IDE extension for VSCode
- Open this project folder in VSCode
- PlatformIO will automatically install required dependencies:
- Servo library (v1.2.1 or later)
- Connect your Arduino Uno to your computer via USB
- In VSCode:
- Click the PlatformIO icon in the sidebar
- Under Project Tasks:
- Click "Build" to compile
- Click "Upload" to flash to Arduino
- Use "Monitor" to view serial output (when debugging is enabled)
- Serial monitor is configured at 9600 baud
- Normal Mode: Use the push button to cycle through gates. After selecting a gate, wait briefly and it will open automatically.
- Meter Mode: For calibrating AC sensors:
- Power off the Arduino
- Press and hold the button
- While holding the button, power on the Arduino
- Release the button after power-up
- LEDs will now act as signal strength indicators:
- Each LED corresponds to an AC sensor
- Turn on a device on the cable being calibrated
- Rotate the sensor clamp around the cable
- LED will blink faster (or become solid) when sensor is optimally positioned
- Debug Mode: Enable detailed serial output by setting DEBUG flag (enabled by default)
- LED Test Mode: Enable by uncommenting DEBUG_LED_TEST in Configuration.h. Flashes each LED in sequence to verify connections.
- Servo Test Mode: Enable by uncommenting DEBUG_SERVO_TEST in Configuration.h. Opens and closes a specified servo with each button press without initializing other components. Set TEST_SERVO_INDEX in Configuration.h to select which servo to test (1 = first servo, 2 = second servo, etc.). Useful for testing servo functionality and calibration. The system will properly handle disabled servos (pins set to -1) by controlling only the LED while skipping servo movement.
All settings can be adjusted in Configuration.h:
- Number of gates (NUM_GATES) - up to 5 supported
- Number of AC sensors (NUM_AC_SENSORS) - typically one per gate
- Number of LEDs (NUM_LEDS) - typically one per gate
- Button pin assignment (BUTTON_PIN)
- CLOSE_DELAY - Time it takes for a gate to close (ms)
- OPEN_DELAY - Time after last button push to open gate (ms)
- MAX_BLINK_LEN - LED blink rate (adjusted automatically in debug mode)
- NUM_OFF_SAMPLES - Number of samples for checking average sensor off values
- NUM_OFF_MAX_SAMPLES - Milliseconds to sample for max off value at startup
- AVG_READINGS - Number of readings to average when triggering gates (max 50)
- AC_SENSOR_SENSITIVITY - Trigger threshold multiplier (2.0 = twice max off reading)
The system includes comprehensive protection against AC sensor flutter that could cause rapid servo cycling and potential hardware damage:
- AC_SENSOR_SENSITIVITY_ON (default: 2.0) - Threshold multiplier to turn tool ON
- AC_SENSOR_SENSITIVITY_OFF (default: 1.5) - Threshold multiplier to turn tool OFF (creates hysteresis)
- DEBOUNCE_STABLE_READINGS (default: 3) - Number of consecutive stable readings required before state change
- MIN_SERVO_INTERVAL_MS (default: 2000) - Minimum milliseconds between operations on the same gate
- MAX_OPS_PER_MINUTE (default: 10) - Maximum operations per minute before emergency shutdown
- ERROR_FLASH_INTERVAL_MS (default: 200) - LED flash interval when in error state
- Hysteresis: Uses different thresholds for turning ON (2.0x baseline) vs turning OFF (1.5x baseline) to prevent rapid toggling around a single threshold
- Debouncing: Requires 3 consecutive stable sensor readings before changing gate state, filtering out momentary noise spikes
- Minimum Interval with Queuing: Enforces 2-second minimum between operations on the same gate
- If a gate operation is requested during the cooldown period, it is automatically queued
- The queued operation executes automatically once the minimum interval expires
- This ensures responsive operation while preventing rapid cycling
- Example: If you turn on a tool immediately after turning it off, the gate will open automatically 2 seconds later
- Rate Limiting: Tracks operations per minute and enters error state if limit exceeded
- Error State: When too many operations detected (flutter condition):
- All LEDs flash rapidly in error pattern
- All automatic gate operations are disabled
- System requires restart to recover
- Alerts user to problematic sensor or configuration issue
- Servo pins (SERVO_PIN_1 through SERVO_PIN_5)
- Set any servo pin to -1 to disable that servo while maintaining the gate numbering
- Example: Setting SERVO_PIN_2 to -1 disables the second servo but keeps gate 3 as "gate 3" in the UI
- AC sensor pins (AC_SENSOR_PIN_1 through AC_SENSOR_PIN_5)
- LED pins (LED_PIN_1 through LED_PIN_5)
- SERVO_MAX_x - Maximum position for each servo (typically 180 degrees)
- SERVO_MIN_x - Minimum position for each servo (typically 0 degrees)
- GATE_CLOSED_AT_MAX_x - Determines gate orientation:
- Set to true (default) if gate is closed when servo is at max position
- Set to false if gate is open when servo is at max position (inverted)
- Set any servo's MAX/MIN values even if the pin is disabled (-1) to maintain consistent configuration
- src/BlastGateServo.cpp - Main program file with setup and loop
- include/Configuration.h - All user configurable settings
- include/GateServos.h/cpp - Servo control and position management
- include/AcSensors.h/cpp - AC current sensor reading and threshold detection
- include/Debug.h - Debug output macros and configuration
- platformio.ini - PlatformIO project configuration and library dependencies
- Created 2019-01-02 - Greg Pringle
- Updated 2019-01-20 - Greg Pringle - Added AC sensor support
- Updated 2025-01-26 - Added VSCode/PlatformIO support
- Updated 2025-02-16 - Added detailed configuration documentation and converted to proper C++ structure
- Updated 2025-02-26 - Added support for disabling specific servos (set pin to -1) while maintaining gate numbering
- Updated 2025-02-26 - Fixed button timing logic to properly open gates after selection
- Updated 2025-02-26 - Improved timer logic to ensure gates open/close reliably, reduced OPEN_DELAY to 800ms
- Updated 2025-02-26 - Implemented proper button debouncing and state machine for more reliable operation
- Updated 2025-02-26 - Fixed issue with servos not moving when button was pressed
- Updated 2025-02-26 - Enhanced gate selection to automatically skip disabled gates when cycling through options
- Updated 2025-02-27 - Fixed compiler warnings in Configuration.h (removed redundant header guard and corrected version number format) and in GateServos.h (fixed signed/unsigned comparison by changing opendelay type to unsigned long)
- Updated 2025-02-27 - Added gate orientation configuration (GATE_CLOSED_AT_MAX_x) to support different physical gate setups where gates may be open when up or closed when up
- Updated 2025-12-08 - Implemented comprehensive flutter protection system to prevent AC sensor flutter from damaging hardware:
- Added hysteresis (different ON/OFF thresholds) to prevent rapid state toggling
- Implemented debouncing requiring 3 consecutive stable readings before state change
- Added minimum 2-second interval between servo operations on same gate with automatic queuing
- Operations requested during cooldown are queued and execute automatically when interval expires
- Implemented rate limiting with emergency shutdown if more than 10 operations per minute
- Added error state with flashing LED pattern and system halt on flutter detection
- All protection settings are configurable in Configuration.h