High precision automatic scheduling of task sets for microcontrollers

Abstract

In low-end microcontroller systems task scheduling is often not done, performed using very ad-hoc methods, or using a high-overhead RTOS. In this paper we offer an alternative: the design-time generation of high-precision schedules which are then executed using a minimal scheduler on a microcontroller. The schedules are derived from a simple task modeling language that allows the specification of properties of tasks, constraints on task execution, as well as worst-case interrupt rates and interrupt service execution times. An off-line scheduling algorithm then computes a schedule for the tasks specified which is then compiled and linked with a simple execution kernel that performs the scheduling. The paper describes the modeling language, the schedule computation approach used, the run-time kernel, as well as experimental results.