IT Command — Digital Input Debounce
The IT command configures debounce (anti-bounce) times for digital inputs and ignition, preventing false alarms.
What is it for?
🚪 Door sensors — Filters mechanical bouncing when opening/closing
🔑 Stable ignition — Prevents false changes when starting engine
🆘 Panic button — Quick response with bounce filtering
📳 Vibration sensors — Ignores normal vehicle vibrations
Allows defining independent delays for positive (ON) and negative (OFF) edges.
Syntax
| Operation | Command | Description |
|---|---|---|
| Configure | SITindex delay_on delay_off | Define debounce times |
| Query | QITindex | Read current configuration |
Parameters
| Field | Description | Range |
|---|---|---|
index | Digital input or IGN | 00-06 (IN), 07 (IGN) |
delay_on | Tenths of second + edge | 0001-9999 |
delay_off | Tenths of second - edge | 0001-9999 |
Default Values
| Input | Debounce ON | Debounce OFF |
|---|---|---|
| IN00-IN06 | 100 ms | 100 ms |
| IGN (07) | 10000 ms (10s) | 10000 ms (10s) |
The ignition sensor has 10 seconds debounce by default to prevent false state changes when starting the engine.
Examples
Door sensor with anti-bounce
>SIT0200100003<
// IN02: ON=1.0s, OFF=0.3sBehavior:
- 🚪 Door must be open for 1s to generate
IN02+ - 🚪 Door must be closed for 0.3s to generate
IN02-
>QIT02<
>RIT0200100003;ID=1234;*3A<
// Configuration confirmationVibration sensor
>SIT0100500050<
// IN01: both edges 5.0 seconds
// Prevents alarms from momentary vibrationsPanic button (quick response)
>SIT0300020001<
// IN03: ON=0.2s (fast), OFF=0.1s
// Immediate activation with mechanical bounce filteringCustom ignition
>SIT0700200020<
// IGN: both edges 2.0 seconds
// Reduces debounce from 10s to 2s for stable systemsRecommended Times
By Sensor Type
| Sensor Type | ON (ms) | OFF (ms) | Reason |
|---|---|---|---|
| Door | 100-500 | 50-200 | Avoid mechanical bounce |
| Vibration | 500-2000 | 500-2000 | Filter normal vibrations |
| Button | 20-100 | 10-50 | Quick response |
| Pressure | 1000-5000 | 1000-5000 | Stabilize readings |
| Temperature | 2000-10000 | 2000-10000 | Avoid transient changes |
| Ignition | 1000-10000 | 1000-10000 | Filter startups |
| Impact | 10-100 | 10-100 | Immediate detection |
Considerations
Very long debounce times (>30s) may cause loss of legitimate events. Adjust according to specific application.
For critical applications (panic button, impacts), use minimum debounce (10-50ms) and validate events on platform.
Relation with Events
Debounce affects when triggers are generated:
// Without adequate debounce (default 100ms)
Door opens/closes quickly → multiple IN02+/IN02- events
// With appropriate debounce (1000ms)
>SIT02 1000 0300<
Door opens/closes quickly → no events (doesn't reach time)
Door opens and stays open → IN02+ event after 1sCompatibility
See Also
- IO Command - Input/output query
- SS Command - Input signals
- Event Engine - Events with inputs
- Trigger List - IN00-IN06 events