single edge nibble transmission (sensor) (SENT)

Single EdgeNibbleTransmission (SENT) is a serial transport protocol that meets the increasing use of sensors in automotive technology and transports the data from the sensors to the control units. Since not all sensors in motor vehicles can be efficiently connected to fieldbuses, the SENT protocol provides a transport protocol for on- board electronics that supports high data rates.

The SENT protocol was specified by American car manufacturers under the leadership of General Motors. It is characterized by its simplicity and operates on an unshielded three- wire connection via which the sensors also receive their supply voltage. Transmission using the SENT protocol is digital and relatively uncritical to interference signals. This is due to the fact that the information content is only in the falling signal edge (single edge), whereby the time between two falling pulse edges contains the information of the nibbles. The transmitted value of a nibble is proportional to the duration between two falling pulse edges. The entire SENT protocol consists of a string of nibbles. There is a minimum duration of 36 µs for a nibble, which increases by 3 µs at each level of nibble valence. For example, if the quadbit 0100 has a duration of 48 µs, then the following 4-bit word 0101 has a duration of 51 µs. The transmission is synchronized by a synchronization pulse that is transmitted before the nibbles.

The advantage of the SENT protocol can also be seen in the fact that the data is transmitted digitally after A/D conversion in the sensor all the way to the control unit and is processed digitally in the control unit.

The SENT protocol is an open standard released by the Society of Automotive Engineers( SAE).