Synchron -- An API and Runtime for Embedded Systems

TL;DR

Synchron introduces a high-level API and runtime system for embedded programming, simplifying concurrency, I/O, and timing concerns with abstractions and supporting microcontrollers, demonstrated through expressiveness and performance benchmarks.

Contribution

It presents Synchron, a novel API and runtime for embedded systems that combines high-level abstractions with low-level support, enabling easier programming of concurrent, timing-sensitive applications.

Findings

Expressive state machine examples demonstrated

Timing features validated with music programming

Benchmark results show acceptable response time, jitter, memory, and power usage

Abstract

Programming embedded systems applications involve writing concurrent, event-driven and timing-aware programs. Traditionally, such programs are written in low-level machine-oriented programming languages like C or Assembly. We present an alternative by introducing Synchron, an API that offers high-level abstractions to the programmer while supporting the low-level infrastructure in an associated runtime system and one-time-effort drivers. Embedded systems applications exhibit the general characteristics of being (i) concurrent, (ii) I/O-bound and (iii) timing-aware. To address each of these concerns, the Synchron API consists of three components: (1) a Concurrent ML (CML) inspired message-passing concurrency model, (2) a message-passing--based I/O interface that translates between low-level interrupt based and memory-mapped peripherals, and (3) a timing operator, $syncT$, that marries CML's $sync$ operator with timing windows inspired from the TinyTimber kernel. We implement the Synchron API as the bytecode instructions of a virtual machine called SynchronVM. SynchronVM hosts a Caml-inspired functional language as its frontend language, and the backend of the VM supports the STM32F4 and NRF52 microcontrollers, with RAM in the order of hundreds of kilobytes. We illustrate the expressiveness of the Synchron API by showing examples of expressing state machines commonly found in embedded systems. The timing functionality is demonstrated through a music programming exercise. Finally, we provide benchmarks on the response time, jitter rates, memory, and power usage of the SynchronVM.