How SENT communication works?

　・In Japanese
前提知識
　・Serial communication
　・LIN communication
　・One-way communication
　・Differential signal transmission

■What is SENT communication?

SENT communication is an abbreviation for Single Edge Nibble Transmission, and is a serial communication standard mainly used as a communication network for automobiles. When inputting sensor information to the ECU, there is an analog input that linearly inputs the voltage value of the sensor, but SENT is a method of communicating as a digital signal.

The advantage of digital communication is that sensor values can be entered with high accuracy. A high-precision sensor performs various signal processing within the sensor, and in the process converts the analog signal to a digital signal, so there is no reason to convert it again to an analog signal to send it to the ECU. Converting to analog signals results in quantization errors (AD conversion errors) and noise in the transmission process.

■Advantages of SENT over LIN communication

Another digital communication between the sensor and ECU is LIN communication, but SENT has the advantage of faster communication speed than LIN. The communication speed of SENT is 30Kbps, which is a dedicated line for a single sensor, and LIN is 20Kbps, which shares a communication line with multiple sensors, so the communication speed of LIN is slow. If speed is not required, LIN communication is fine.

■Characteristics of SENT communication

The characteristics of serial communication are one-way communication and single-ended transmission using one line because it is dedicated to transmission. A characteristic of SENT communication is that signals are sent in 4-bit units (4 bits are called nibbles), and the duration of the signal is determined by the time between the falling edges of the voltage.



The description of the transmission signal is below.

・sync signal
Signal to recognize the start of one cycle.

・status
Communication status, such as whether it is out of order.

・signal 1, 2
sensor value itself. It is possible to send two types of sensor values. It is not always 12bit each, it is possible to change 10bit/14bit.

・CRC
Cyclic redundancy check signal.

・pause pulse
Adjustment signal for making the total number of ticks in one cycle the same. Not necessarily.

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