Adapting an IP MC6805 core for multiprocessing and multitasking

Abstract

La disponibilidad de dispositivos de Lógica Programable de alta densidad de integración permite buscar soluciones integradas en un dispositivo SOPC (System On a Programmable Chip). Un tema de creciente interés son los procesadores empotrados, siendo usual un único procesador y un sistema operativo con capacidad de multitarea. Sin embargo, debe considerarse como alternativa insertar varios procesadores, no necesariamente idénticos, que pueden a su vez atender varias tareas. En un SOPC, como diferencia fundamental con los casos tradicionales de multiprocesamiento y multitarea, las tareas a realizar son conocidas antes de comenzar el diseño, por lo tanto hardware como software se pueden configurar a medida de la aplicación, combinando la velocidad propia del primero, con la versatilidad del segundo. Este artículo describe las modificaciones de hardware realizadas al núcleo IP (Intellectual Property) de un procesador, de modo de permitir la inclusión de un administrador de tareas por hardware y de canales de comunicación interprocesadores.

The availability of high-density field configurable devices provides the opportunity for designing highly integrated solutions (SOPC: System On a Programmable Chip). Among the SOPC solutions, a case is the integration of an embedded single processor equipped with a multitasking operating system. As an alternative to a single processor the embedding of various processors on a chip, even heterogeneous and with multitasking capacity, may be considered. A distinctive characteristic of a SOPC device is that the tasks to be performed are well known before the design starts. That feature is opposed to the traditional multiprocessing and multitasking systems in which general purpose applications are adopted during design. The benefit of this knowledge is that hardware as well as software can be adapted to fit the application’s requirements. This paper presents the hardware modifications performed on an microcontroller embedded core, to allow its inclusion as a multitasking device in a “multiprocessor on a chip”, through the addition of a hardware task manager (scheduler) and communication channels among processors.