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Model-Based Design for Embedded Systems- P28

Model-Based Design for Embedded Systems- P28: This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. | 236 Model-Based Design for Embedded Systems The second layer consists in the OS and communication middleware Comm layer. This software layer is responsible for providing the necessary services to manage and share resources. The software includes scheduling of the application tasks on top of the available processing elements intertask communication external communication and all other types of resource management and control services. Conventionally these services are provided by the OS and additional libraries for the communication middleware. At this level the hardware dependency is kept functional i.e. it concerns only high level aspects of the hardware architecture such as the type of available resources. The OS and communication layer make use of HAL APIs to abstract the underlying HAL layer. Low level details about how to access these resources are abstracted by the third layer which is the HAL. The separation between OS and HAL makes thereby the architecture exploration for the design of both the CPU subsystem and the OS services easier enabling easy software portability. The HAL is a thin software layer that not only completely depends on the type of processor that will execute the software stack but also depends on the hardware resources interacting with the processor. The HAL also includes the device drivers to implement the interface for the communication with the various devices. 9.2.3 Hardware-Software Interface The hardware-software interface links the software part with the hardware part of the system. As illustrated in Figure 9.4 the hardware-software interface needs to handle two different interfaces one on the software side using APIs and one on the hardware side using wires 11 . This heterogeneity makes the hardware-software interface design very difficult and time consuming because the design requires both hardware and software knowledge FIGURE 9.4 Hardware-software interface. Programming Models for MPSoC 237 as well as their interaction 12 . The