SENT (protocol)

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The SAE J2716 SENT (Single Edge Nibble Transmission) protocol [1] is a point-to-point scheme for transmitting signal values from a sensor to a controller. It is intended to allow for transmission of high resolution data with a low system cost.

Hardware[edit]

The SENT protocol is a one-way, asynchronous voltage interface which requires three wires: a signal line (low state < 0.5V, high state > 4.1V), a supply voltage line (5V) and a ground line.

Software[edit]

Data is transmitted in units of 4 bits (1 nibble) for which the interval between two falling edges (single edge) of the modulated signal with a constant amplitude voltage is evaluated. A SENT message is 32 bits long (8 nibbles) and consists of the following components: 24 bits of signal data (6 nibbles) that represents 2 measurement channels of 3 nibbles each (such as pressure and temperature), 4 bits (1 nibble) for CRC error detection, and 4 bits (1 nibble) of status/communication information. Optionally, data can be transferred in 20 bit messages (5 nibbles) composed of a single 12 bit (3 nibble) measurement, a 4 bit (1 nibble) CRC error checksum, and a 4 bit (1 nibble) status/communication field.

The image below shows the SENT signal described above. In this case a Pause Pulse is used. The Pause Pulse compensates for the varying length of the messages.

The image shows a main trace with 6 consecutive SENT messages. The zoom of the main trace shows more details of a single SENT message

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