Emulation of Automotive Communication protocol Single Edge Nibble Transmission(SENT) using Aurix Family of Microcontrollers

摘要

Point to point communication between sensor and the Embedded Control Unit (ECU) is a very important and basic task in automotive domain. But, there are no efficient protocols to implement the same. Earlier protocols used to fulfill the communication between Transmitter (sensor) and receiver (ECU) is Analog output protocol and Pulse width modulation protocol. But, there are many difficulties w.r.t cost, speed, diagnosis etc... So, the alternate solution to replace the two earlier protocols and improve the performance w.r.t Speed of operation and Cost is the Single Edge Nibble Transmission (SENT) Protocol. SENT is a unidirectional communication scheme from sensor/transmitting device to receiving/ECU. The sensor signal is transmitted as a series of pulses with data encoded as falling to falling edge periods. Details of the signal encoding may vary for specific sensor. SENT frame sent from the sensor will be received by the TIM (Timer Input Module), sub module of GTM (Generic Timer Module). Another sub module of GTM namely MCS (multichannel sequencer) is used to process the frame. MCS is configured such that it allows +/20% clock deviation for the data frames; detects CRC errors; generates interrupts on CRC error, data error, calibration error etc. SENT (Single Edge Nibble Transmission) defines a level of standardization in the implementation of the digital pulse scheme for reporting sensor information. This standard will allow ECU and tool manufacturers to satisfy the needs of multiple end users with minimum modifications to the basic design. This will benefit vehicle Original Equipment Manufacturers (OEMs) by achieving lower ECU costs due to higher industry volumes of the basic design.