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mbedded.ninja

A Comparison Of Embedded Platforms And HALs

Authors:
Geoffrey Hunter
Geoffrey Hunter
Published On:
May 11, 2021
Last Updated:
May 11, 2021

This is a opinioned review of the many different “platforms” available for use when you want to develop firmware to run on your microcontroller.

Who wants to be trying to find the missing register information in a 1000 page technical reference manual when someone has already done the work for you and provided a HAL (hardware abstraction layer).

Shall be rated under the following categories:

  • HAL
  • RTOS Support
  • Dependency Management
  • Library Support
  • IDE Support
  • Community Support: This one is a bit of a popularity contest. How many and how active are the forums on this platform? Are there lots of StackOverflow questions and responses?

Arduino

Ratings

HAL: 7/10

The documentation for the Arduino API is o.k. Not bad, not great, but generally acceptable.

RTOS Support: 4/10

Dependency Management: 6/10

Library Support: 5/10

IDE Support: 9/10

Community Support: x/10

Comments

Most popular. No built-in or bundled RTOS. Global, constant definitions/peripherals can hinder the flexibility. yield() based co-routines.

Many Arduino libraries make assumptions about what SPI/I2C peripheral you are using. For example, most just assume (and use) the SPI interface), which is a global variable to your first SPI interface.

Digital and analogue pins are read from/written to using global functions like digitalRead(). Whilst this is simple and easy to use, it does impose some limitations when trying to perform unit testing and create mock hardware. Without any Pin objects, you cannot really utilize dependency injection to replace real hardware pins with mocked test pins (although you could pass in the digitalRead() function, and then mock that?).

PlatformIO

Ratings

HAL: n/a

Being a build system and package manager PlatformIO does not provide any HAL.

RTOS Support: n/a

Being a build system and package manager PlatformIO does not provide any RTOS.

Dependency Management: 9/10

Unsure of the amount of support for libraries of libraries (dependencies of dependencies).

Library Support: 5/10

IDE Support: x/10

Community Support: x/10

Comments

PlatformIO is a package manager and build system. It can be used together with many of the platforms mentioned here that do provide a HAL, such as Arduino, mbed or Zephyr.

mbed

HAL: n/a

RTOS Support: 8/10

The mbed HAL comes packaged with an RTOS. When not using multiple threads, a compile time switch disables the scheduler code and you are left with just the one thread.

Dependency Management: x/10

Library Support: x/10

IDE Support: x/10

Mbed provides the Mbed Studio IDE for firmware development and debugging.

Community Support: x/10

Comments

Only polling support for SPI.

Zephyr

Lacking C++ support for:

  • Dynamic memory allocation via new or delete
  • No exception support
  • No RTTI

cmsis