Using real-time system design methods to integrate SMPS control software with application software

A switch-mode power supply (SMPS) converts power efficiently between different voltage levels, making power optimizations through voltage scaling feasible. SMPS controllers are generally dedicated hardware (analog/digital circuits, microcontroller (MCU), digital signal processor (DSP)), and so are expensive to add to very low cost embedded applications. In this work, we show how to integrate SMPS control software into the MCU running application software, which reduces system cost while increasing the design space and flexibility for developers. Real-time system design methods are employed to ensure SMPS voltage regulation quality, while retaining the original embedded application behavior. Our methods apply to a wide range of software task schedulers, from simple interrupt-based foreground/background systems to sophisticated preemptive real-time kernels (RTOS). We demonstrate our methods on a position-logging embedded system, with multiple voltage domains controlled in software, resulting in power savings.