Not every signal in a modern vehicle rides a shared bus at all — a huge number of sensors talk over a single dedicated wire using SENT.
SENT (Single Edge Nibble Transmission, SAE J2716) is a point-to-point protocol for getting a single sensor's reading from the sensor itself to the ECU it feeds - a pedal position sensor, a pressure transducer, a throttle position sensor, a steering angle sensor. Unlike CAN or LIN, SENT isn't a shared multi-node bus at all: it's one wire, one sensor, one receiving ECU input, which is exactly why it doesn't need addressing, arbitration, or a message ID - there's never more than one possible sender on that wire.
It exists because a growing number of sensors are digital rather than simple analog voltage outputs (which drift with temperature and are vulnerable to noise pickup over any significant wire length), but don't need or justify a full CAN transceiver's cost and complexity just to report one continuously-updating value.
SENT's defining trick is encoding data purely in timing, not voltage levels - it sends a sequence of falling-edge-to-falling-edge pulses, and the duration of each pulse encodes a 4-bit "nibble" of data. A base tick time (typically 3 microseconds, agreed between sensor and ECU) defines the unit; a nibble's value is read from how many ticks long its pulse is.
| Frame part | Purpose |
|---|---|
| Sync/calibration pulse | A fixed-length pulse the receiver uses to (re)calibrate its exact tick-time measurement, since the sender's clock isn't perfectly known in advance |
| Status/communication nibble | Frame status flags |
| Data nibbles | Typically 1-6 nibbles, carrying the actual sensor reading |
| CRC nibble | Error checking over the frame |
Because the calibration pulse is sent at the start of every frame, a SENT receiver never needs a pre-shared, precisely matched clock the way some other protocols do - it re-synchronises continuously, which is part of what keeps sensor-side hardware cheap.
Most SENT sensors send two logically separate data streams on the one wire: a fast channel (the main, high-update-rate reading - e.g. pedal position itself) carried in every frame, and a slow channel (secondary, lower-priority data - e.g. sensor status, diagnostic information, a secondary redundant measurement) spread across several frames since it changes less often and can tolerate more latency.
SENT capture and decoding sits within ONAC's automotive electronics and vehicle network systems work - relevant wherever a sensor-level signal, not just the vehicle's shared bus traffic, is the actual subject of an investigation.