MCUSW
Overview of MCAL

MCAL Documentation

1.1 Overview of AUTOSAR Stack

AUTOSAR (AUTomotive Open System ARchitecture) is an open and standardized automotive software architecture jointly developed by automobile manufacturers, suppliers, and tool developers. AUTOSAR focuses on strategic targets such as modularity, configurability, and transferability of software modules, and the standardization of their interfaces.

AUTOSAR is based on the concept of separation between infrastructure and application. AUTOSAR software component implementation is independent from the infrastructure.

Autosar infrastructure consists of the following layers:

  1. Runtime Environment (RTE): Middleware layer providing communication services for the application software and making components independent of a specific MCU.
  2. Basic Software (BSW) Layer: Layer with basic services and drivers to leverage the underlying hardware, enabling interface to application and RTE layer.
  3. Services Layer: Offers basic services, memory services, diagnostic services, and state management for components in the basic layer.
  4. ECU Abstraction Layer: Interfaces the drivers of MCAL and makes higher software layers independent of hardware layout; offers access to I/O signals.
  5. Microcontroller Abstraction Layer (MCAL): The lowest software layer, designed to make higher-level software independent of the microcontroller.
  6. Complex driver: A collection of complex sensor and actuator control or non-standardized drivers that may need migration.

1.2 What is MCAL


MicroController Abstraction Layer (MCAL) is a software module enabling direct access to on-chip MCU peripheral modules and making the upper software layer independent of the MCU.

The Microcontroller Abstraction Layer (MCAL) is the lowest layer of the AUTOSAR Basic Software architecture. MCAL contains drivers with direct access to the microcontroller internal peripherals and memory-mapped microcontroller external devices. MCAL is hardware-specific, ensuring a standard interface to the Basic Software. It manages the microcontroller peripherals and provides the components of the Basic Software with microcontroller-independent values. MCAL also implements notification mechanisms to support the distribution of commands, responses, and information to processes.

AUTOSAR MCAL Layer

Fig. 1.1: AUTOSAR MCAL Layer

MCAL software (part of the package that includes the hardware platform) must be configured for the specific automotive application. For example, a CAN BUS (MCAL) driver needs to be configured for in-vehicle networking; similarly, drivers like LIN BUS, FlexRay, PWM, SPI, and Ethernet must be configured based on the application’s needs.

Configuration of these drivers is carried out by specialized code generation and configuration tools (for example, EB Tresos). The source files generated by such tools contain structures with elements like configuration values, based on the Parameter Definition File. These values are then fed to peripheral registers, address pointers, macro definitions, etc.

The MCAL drivers implement the software specification from AUTOSAR 4.3.1. Additionally, examples demonstrating MCAL driver usage have been included.


1.3 What is CDD

CDD stands for Complex Device Drivers. A Complex Driver is a software entity that provides for the integration of special-purpose functionality/drivers not defined in AUTOSAR. A CDD resides in the Complex Drivers Layer of the Basic Software and interacts with standard BSW modules or the RTE.

  • A CDD may need to interface with modules of the layered software architecture.
  • A module of the layered software architecture may need to interface with a CDD.
  • A CDD may need to interface with SW-Cs via the RTE.

CDD in Layered Software Architecture

Fig. 1.2: CDD in Layered Software Architecture

The main goal of the CDD is to implement complex sensor evaluation and actuator control with direct access to the microcontroller (via specific interrupts or complex microcontroller peripherals, external devices, etc.) to fulfill special functional and timing requirements. In addition, it might be used to implement enhanced services / protocols or to encapsulate legacy functionality of a non-AUTOSAR system.

CDD implementation may be application-, microcontroller-, and ECU-dependent. Lastly, the CDD can serve as a mechanism of migration to introduce existing or new concepts into the AUTOSAR Software Architecture.

Refer to AUTOSAR_EXP_LayeredSoftwareArchitecture for more details on CDD-related configurations.


1.4 MCAL Safety Strategy

1.4.1 Safety Certified MCAL Modules

MCAL is a collective package of Safety Certified Driver Modules (ASIL D/B depending on the device), developed with a process certified for ISO 26262 compliance.

Drivers implement hardware safety mechanisms (as listed in the HW Safety Manual) to address random faults.

  • Intermediate release versions will be supported by CSP for the delta changes with the impact analysis from certified version.

1.4.2 CSP

The Software Compliance Support Package (CSP) is the collection of documentation that TI offers to help customers with their certification processes for the integrated system. CSP will be made available in mySecure SW as an independent package two weeks after the official MCAL release.

The CSP helps customers qualify MCAL in their system context. This is necessary if the software is modified or the tooling changed such that TI’s functional safety assessment of MCAL is invalidated.

Each HW IP Module MCAL driver has its own CSP for customers.


1.5 Software Offering

TI offers MCAL and CDD drivers (source code) for MCU devices, along with a licensed Configurator Package. The rest of the AUTOSAR Basic Software is provided by various AUTOSAR vendors (Vector, Elektrobit, ETAS, etc.).

Software Offering

Fig. 1.3: Software Offering

Customers receive:

  • MCALs and EB Configurator Tool from TI
  • AUTOSAR BSW/RTE from their chosen vendor with an OS port for the target TI device

The customer then integrates these deliverables based on integration guides from the AUTOSAR vendor and TI. Back To Top