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Glossary

Note

This glossary does not intend to provide complete definitions of each term. Instead, it aims to clarify and emphasize the differences between related terms. Links are provided when relevant to learn more about each concept.

  • Ariel OS HALs: currently the following crates: ariel-os-esp, ariel-os-nrf, ariel-os-rp, and ariel-os-stm32.

  • ARM (or Arm): a family of instruction set architectures.

  • Arm (Arm Holdings): the company behind the ARM architecture family.

  • Chip: an integrated circuit (IC).

  • Cortex-M: a family of 32-bit processor implementations from Arm.

  • ESP32: a family of 32-bit microcontrollers from Espressif. Its older microcontrollers are based on the Xtensa architecture, while newer ones use RISC-V. Can also specifically refer to the eponymous ESP32 microcontroller.

  • Embassy: a software project developing HALs for multiple microcontroller families (e.g., embassy-nrf, embassy-rp, embassy-stm32), along with other components (e.g., embassy-executor, embassy-time).

  • Embassy-style HALs: currently the following crates: embassy-nrf, embassy-rp, embassy-stm32, and esp-hal. In particular, these HALs feature peripheral ZSTs modeling compile-time exclusive access, that drivers require for instantiation.

  • esp-hal: a HAL for ESP32 microcontrollers, developed by their manufacturer Espressif.

  • HAL (Hardware Abstraction Layer): a software layer that makes specific pieces of hardware (e.g., microcontroller peripherals) easier to use, by hiding some of their details.

  • MCU: a microcontroller. Contains a processor, memory, and peripherals to interact with the outside world.

  • nRF: a family of 32-bit microcontrollers developed by Nordic Semiconductor.

  • Raspberry Pi: can refer to the family of single-board computers or to Raspberry Pi Holdings, the company that manufactures them as well as RP microcontrollers. Sometimes abbreviated to “RPi.”

  • RISC-V: an open, royalty-free instruction set architecture.

  • RP: a family of 32-bit microcontrollers designed by Raspberry Pi, which includes the RP2040 and RP2350 microcontrollers.

  • SoC (System on Chip): often synonymous with microcontroller in practice, at least in the embedded domain. Sometimes used to emphasize the presence of a sizable analog component (usually for radio).

  • STM32: a family of 32-bit microcontrollers developed by STMicroelectronics.

  • UART (Universal Asynchronous Receiver-Transmitter): a (microcontroller) peripheral. By extension, can also refer to the link-layer protocol it implements. Sometimes incorrectly used to refer to serial communication over USB (e.g., instead of USB CDC-ACM).

  • USB CDC-ACM: a standard protocol implementing serial communication over USB.

  • USB CDC-NCM: a standard protocol implementing Ethernet over USB.

  • Xtensa: a family of instruction set architectures, used in some ESP32 microcontrollers.