TI — True Ignition
Configures voltage-based ignition detection. When enabled, the device determines vehicle ON/OFF state from the main battery/charging voltage instead of the hardware ignition input.
Overview
In many vehicles, battery voltage rises above ~13.0V when the alternator is charging (engine ON) and drops below ~13.0V when the engine is OFF. True Ignition uses this behavior to detect ignition state without requiring a dedicated ignition wire.
Default behavior (TI not configured): Ignition state is determined by the hardware ignition input (signal F00).
When TI is configured: Ignition state is derived from the main power ADC voltage and the hardware ignition input is ignored.
Format
- Set (enable):
>STI1{THRESHOLD}< - Set (disable):
>STIU< - Query:
>QTI<
Set Command
| Field | Description |
|---|---|
1 | Action: enable True Ignition |
U | Action: disable/delete True Ignition |
{THRESHOLD} | Voltage threshold in millivolts (required when enabling) |
Query Response
When TI is not configured:
>RTIU{DEFAULT_THRESHOLD},{ADC_VALUE}<
When TI is configured:
>RTI1{THRESHOLD},{ADC_VALUE}<
| Field | Description |
|---|---|
U or 1 | U = undefined/disabled, 1 = configured/enabled |
{THRESHOLD} | Configured threshold in mV (or default 13000 when undefined) |
{ADC_VALUE} | Current main power ADC reading in mV |
Default Threshold
- 13000 mV (13.0V)
Examples
Enable True Ignition with default 13.0V threshold:
>STI113000<
>RTI113000<
Enable with custom 12.8V threshold:
>STI112800<
>RTI112800<
Query current state (configured):
>QTI<
>RTI113000,13200<
Query current state (not configured):
>QTI<
>RTIU13000,13200<
Disable True Ignition (restore hardware ignition):
>STIU<
>RTIU<
Stability Logic
The detector uses hysteresis and consecutive-sample debounce to prevent rapid toggling near the threshold:
| Parameter | Value | Description |
|---|---|---|
| ON threshold | Configured threshold | Voltage must exceed this to turn ON |
| OFF threshold | Configured threshold − 200 mV | Voltage must drop below this to turn OFF |
| Consecutive samples | 3 | Number of consecutive qualifying readings required |
State Transitions
- OFF → ON: Voltage must remain ≥ ON threshold for 3 consecutive samples (~3 seconds).
- ON → OFF: Voltage must remain ≤ OFF threshold for 3 consecutive samples (~3 seconds).
- Voltages between ON and OFF thresholds do not cause transitions (hysteresis band).
Ignition Source Behavior
| TI State | Ignition Source | Signal |
|---|---|---|
| Not configured | Hardware ignition input | F00 from yellow wire |
| Configured | Main power ADC voltage | F00 from red wire voltage |
The rest of the system continues reading F00 transparently — only the source changes internally.
AD Extended Tag
The AD extended tag reports the current main power ADC value (in mV) used as the True Ignition source. This value is reported regardless of whether TI is configured.
Format: ;AD={value}
Example event with AD tag:
;AD=13200
Persistence
The TI configuration (enabled state + threshold) is stored persistently in the interface database. It survives device reboots.
Notes:
- This functionality is only available for 12V vehicles.
- True Ignition is not supported in Power Saving Mode (PSM). If PSM is required, configure alternative wake-up criteria such as motion detection.