Development of a Demonstrator with Samples of the Input Circuits of the Automotive Control Unit

Abstract

The demonstrator implements the complete Analog input signal chain of the resistive accelerator pedal position sensor ECU component from the sensor itself to the transmission of the signal along the CAN bus to the screen of Vector CANoe where it can be visualised. The hardware elements of the demonstrator are the signal conditioning circuit board and the NXP S32K144EVB-Q100 evaluation board. The firmware that runs on the ARM Cortex-M4F processor of the evaluation board implements a 20 Hz control loop that includes a first-order IIR digital filter, three outputs that represent the transfer characteristic of the sensor (linear, logarithmic, exponential using look-up tables), a six-bit diagnostic status byte, and logic to detect kickdown and simulate the application of torque-cut pulses. All data from the sensor is transmitted over a single CAN message at a rate of 500 kbit/s, decoded by a custom DBC file and a dashboard panel within CANoe. Four laboratory assignments were developed as part of this project that will focus on different topics related to the ECU, such as kickdown, the transfer characteristic of the sensor, digital filtering, and CAN diagnostics. This project represents an effort to bridge the gap between the theoretical knowledge of the components of ECUs that is gained in the classroom and their use within the laboratory. Overall, the demonstrator introduces students to the hardware of an ECU, as well as allows them to code with S32 design studio in order to change the behaviour of the output. and Validate it through CANoe.