Innovative Architecture of a Smart Bidirectional Input /Output Interface Based upon Frugal Engineering Concepts

Automotive megatrends such as connected, autonomous and electrified vehicles are driving penetration of automotive electronic technology in every vehicle subsystem. However, these electronic units need to be interfaced with input/output devices from outside world. The same need to be interfaced with a robust and reusable architecture conforming to automotive norms. When generic electronic control units (ECUs) need to be reused across diverse vehicle families and segments, it is desirable that every ECU pin interfaced with the outside world needs to be capable of performing multiple tasks. This is particularly true of digital outputs (such as solenoids, lamps, on/off motors etc.) and digital inputs (such as command switches, pushbuttons, pressure switches, thermal switches etc.) Current smart switch peripheral ICs can be used only as outputs and cannot be configured as inputs whenever demanded by application requirements. Also, these smart switch architectures provide conservatively generic solutions which prove to be “over engineered” for many digital output solutions such as simple LED or Solenoid controls. This paper proposes a novel smart switch cum input interface architecture which can be optimally tailored to a given set of output load requirements such as current profile, thermal requirements, protection on one hand and a simple digital on/off input interface on the other hand. The architecture design employs a system engineering technique which lists performance requirements and explores alternate architectures to meet the same. All the alternatives are rated on various performance metrics to arrive at the rightmost choice fitting a given application. The paper ends with a design example which covers both hardware philosophy and a state machine based low level command/diagnostic driver. Future directions and opportunities for this solution are discussed at the end.