PSI5 ( Peripheral Sensor Interface 5 ) is an interface for automotive sensor applications. It is used to connect peripheral sensors to electronic control units (ECUs) in automotive electronics. The main features of PSI5 are:
- Two-wire current interface
- Manchester coded digital data transmission
- High data transmission speed of 125kbps and 189kbps
- Wide range of sensor supply current
- Variable data word length (10 to 28 bit with one bit granularity)
- Asynchronous and synchronous operation and different bus modes
- Bidirectional communication
The PSI5 master supplies a pre-regulated voltage to the slave sensor and modulates the supply voltage in the positive direction to provide synchronization of the sensor data. Data transmissions from the sensor to the master are accomplished via modulation of the current on the power supply line.
Figure 1. Voltage and current modulation in PSI5
Validation of PSI5 is a complex task as both power supply and data are present on a single line. The master sends the synchronization pulses on power line (voltage modulation) and slaves respond by sending information using supply current modulation. Both analog and digital information is present in modulated current waveform.
Presently PSI5 Simulyzers are used to validate PSI5 interface in the industry. These simulyzers consist of a hardware part, which communicates with the ECU or the sensor to be validated, and the GUI to control the hardware part. The simulyzer can be set to operate as an ECU for the validation of a sensor, or as a sensor for the validation of an ECU, or as an analyser to analyse the data and signals.
When validating a sensor, a simulyzer provides supply and sync pulses to the sensor. The response from the sensor can be analysed by viewing the signals in the scope within the GUI or by comparing the recorded data with the expected data. The response format that is expected from the sensor is checked by the simulyzer and the CRC checks are