PlatformIO Open Source May Updates

New boards and dev-kits, Support for the latest Espressif ESP-IDF, Updated Arduino Cores for ESP8266, STMicroelectronics STM32, and Mbed-enabled devices

Valerii Koval
Valerii Koval
Head of System Integration at PlatformIO Labs

Welcome to the May 2021 updates of the PlatformIO Open Source professional collaborative platform for embedded development. This month we received a lot of helpful feedback from our community, which let us identify the most important parts of our OSS ecosystem that required our attention, so let’s go through the updates pushed in this month.

PlatformIO Open Source May Updates

During May, we have mostly focused on our thriving Arduino community. Besides updating support for the latest stable ESP-IDF v4.2.1, we updated Arduino cores for ESP8266, ST STM32, Adafruit, and mbed-enabled devices. Some of the key highlights include:

Espressif 8266 dev-platform v3.0

The latest revision of the Espressif 8266 dev-platform brings support for the latest Arduino core v3.0.0 together with the latest GCC toolchain v10.2 and several minor improvements:

Breaking changes

The latest Arduino Core v3.0.0 is a major release that brings several breaking changes including removed and significantly changed APIs. Many popular libraries are not synchronized with these changes which may lead to non-obvious compilation and linker errors. Please thoroughly examine the summary of the changes in the release notes before updating the platform. In case your projects are not compilable after the update, you can always roll back to the previous version of the platform, for example: ini [env:espresso_lite_v2] platform = espressif8266@^2 framework = arduino board = espresso_lite_v2

MMU configuration

This release introduces new configuration defines that allow adjusting the ICACHE to IRAM ratio, for example:

platform = espressif8266
framework = arduino
board = espresso_lite_v2
build_flags =
    ; 16KB Cache + 48KB IRAM and 2nd Heap (shared)

Related resources for the Espressif 8266 dev-platform:

STMicroelectronics STM32 dev-platform v14.0

The new release of the ST STM32 platform comes with a bunch of new boards and dev-kits, support for the latest major release of Arduino core v2.0 and updated SVD files for better debugging experience:


The latest STM32 Arduino Core v2.0.0 is a major release with refactored variant structure. These changes may break custom board manifests which used previous variant names. In case your projects are not compilable after the update, you can always roll back to the previous version of the platform, for example: ini [env:nucleo_f072rb] platform = ststm32@^13.0.0 framework = arduino board = nucleo_f072rb

Related resources for the ST STM32 dev-platform:

Microchip AtmelSAM dev-platform v6.1

The latest release of the Atmel SAM v6.1.0 brings support for new boards, updated Arduino Adafruit core and several minor improvements:

ESP-IDF v4.2.1

The latest version of the Espressif32 platform now supports the latest stable ESP-IDF v4.2.1 - the official development framework for the ESP32 and ESP32-S Series SoCs. It provides a self-sufficient SDK for any generic application development on these platforms, using programming languages such as C and C++. ESP-IDF currently powers millions of devices in the field, and enables building a variety of network-connected products, ranging from simple light bulbs and toys to big appliances and industrial devices.

Major enhancements in the latest release:

  • Improvements to the Bluetooth Controller (reduced IRAM consumption, support for BLE Authorization)
  • Minor optimizations to the Wi-Fi stack
  • Many fixes and improvements to the Peripheral Drivers, Core and Power Management systems

Related resources for ESP-IDF:

Arduino Core for mbed-enabled devices v2.1

The ST STM32, Nordic nRF52 and Raspberry Pi RP2040 dev-platforms have been updated to support the latest Arduino Core for mbed-enabled devices v2.1. According to the release notes, v2.1 brings a lot of bugfixes and improvements in core and accompanying libraries.

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Valerii Koval
Valerii Koval

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