AUTOSAR(AUTomotive Open System Architecture) is an open source layered software development standard for, but not limited to, automotive Electronic Control Unit(ECU). AUTOSAR gives a layered top-down structure for software with relation between the software components. The layered architecture of AUTOSAR can be divided into Basic Software(BSW) , Runtime Environment(RTE) and Application/Software Component layer . Basic Software layer can be further subdivided into Micro-controller Abstraction Layer(MCAL) , ECU Abstraction Later , Services Layer and Complex Device Driver(CDD) Layer . Layered Architecture of AUTOSAR Micro-controller Abastraction layer(MCAL) is the lowest layer in the layered AUTOSAR architecture and it communicates with the hardware directly. Its basic responsibility is to make the layer above it independent of hardware. It houses the low level drivers of the micro-controller. MCAL Layer in AUTOSAR ECU Abstraction