Connecting Things to the IoT by Using Virtual Peripherals on a Dynamically Multithreaded Cortex M3

The Internet of Things communicates with the world by using a wide range of different sensors and actuators. These interfaces are based on a wide range of various protocols, such as I2C, SPI, RS232, 1-wire, and so on. There are two conceptional different solutions to provide these interfaces. One is to use dedicated hardware for it. An example would be to use a peripheral on a system-on-a-chip (SoC). All SoC providers offer the families of SoC solutions with different kind of hardware peripheral combinations. The alternative concept it to run virtual peripherals as a software routine on a CPU, preferable on a multithreaded CPU. C-Slow Retiming (CSR) is a known design transformation to generate multithreaded CPUs. This paper argues, that system hyper pipelining overcomes the limitations of CSR by adding thread stalling, bypassing, and reordering techniques to better cope with the challenges of multithreading. This dynamic multithreaded environment is ideal for running virtual peripheral. The benefits of using system hyper pipelining for virtual peripherals are demonstrated on a Cortex M3-based system.