microPlatform update 0.24

Posted on Jul 12, 2018

14 min read


Zephyr microPlatform changes for 0.24

New console and logging implementations for Zephyr, and an MCUboot heading to v1.2.0.

Linux microPlatform changes for 0.24

No significant changes have gone into this update. The previous update included updates to containers and the sources weren't published. The URL used for authentication in lmp-device-register was updated.

Zephyr microPlatform


New console and logging implementations for Zephyr, and an MCUboot heading to v1.2.0.


  • Zephyr from v1.13
  • MCUboot based on the 1.2.0 release candidate series
  • Minor cleanups to the sample applications




New default PEM file selection:
  • For Zephyr, the default signature file is now set to the root-rsa-2048.pem file in the root of the MCUboot project. This avoids a cryptic error when compiling MCUboot out-of-the-box.
Temporarily enable IRQs in boot_uart_fifo_init():
  • Due to recent scheduler changes, if CONFIG_MULTITHREADING is disabled, main() is called with interrupts locked. Nordic has introduced a temporary patch for boot_uart_fifo_init() which unconditionally enables interrupts to allow the serial recovery mode UART to receive characters. This change will be reverted when the issue in Zephyr is addressed.
CONFIG_SYS_POWER_MANAGEMENT disabled by default:
  • Power management requires multithreading and other kernel features that are disabled in MCUboot, so it was disabled to avoid interrupts being confused.
Use of k_fifo replaced with sys_slist:
  • The kfifo_ primitives are not available when multithreading is disabled, and were replaced with sysslist_ equivalents.
Several changes to serial boot support:
  • The serial boot common code was refactored to allow better platform abstraction, text size reductions and fixed unit tests for MyNewt. A buffer overflow, build issues with ECDSA enabled, and a left over timer getting triggered post image load were also addressed.


Zephyr build fix with ECDSA:
  • A Zephyr build error with ECDSA enabled was fixed.
Several __ASSERT() checks fixed:
  • When CONFIG_MCUBOOT_SERIAL was enabled, several __ASSERT() checks were looking for incorrect values. This has been fixed.



Redundant "default n" removed from Kconfig:
  • A series of Kconfig-related patches removed all redundant default "n" settings across the entire Zephyr tree. This change shouldn't affect behavior; however, it will make any out of tree patches affecting Kconfig files a bit more difficult to merge for this cycle.
Console subsystem refactoring:
  • The console driver/subsystem went through a fairly large refactor to remove the dependency on a FIFO- based console input abstraction. This allows supporting Segger's RTT technology as a console backend. The CONFIG_CONSOLE_PULL knob was renamed to CONFIG_CONSOLE_SUBSYS as part of these changes. This signifies that the subsystem is intended to cover all of Zephyr's console handling (existing and new). Applications using the old configuration name will need updates.
  • Initial Cortex M4 support was added for the i.MX 6SoloX SoC. It's a hybrid multi-core processor composed by one Cortex A9 core and one Cortex M4 core. The low level drivers come from the NXP FreeRTOS BSP and are located at ext/hal/nxp/imx. More details can be found in ext/hal/nxp/imx/README.

Microsemi Mi-V RISC-V softcore CPU support was added for running on the M2GL025 IGLOO2 FPGA development board. This required moving some code from the fe310 platform into the RISC-V privilege common folder.

Zephyr support was added for Nordic's nRF52810 SoC. This is a low-cost variant of the nRF52832, with a reduced set of peripherals and memory. Since Nordic does not offer a development kit for the nRF52810, the nrf52810_pca10040 board definition can be used with the nRF52832-DK (nrf52_pca10040). Using this board definition enforces the limitations imposed by the nRF52810 IC. For more information, see:


An nRF5x peripheral list was created that can be used to describe each nRF5x SoC. Kconfig can use this description to help configure only drivers that are available for a particular SoC.

Support was added for the STM32F7 and STM32F2 series of STM32 SoCs. This includes clock control, entropy, GPIO, flash, pinmux, and UART drivers, as well as several device trees and board definitions for STM32F7 Discovery, STM32F207XG, and STM32F207XE development hardware.

The ESP32 IDF bootloader now has a Kconfig option for compilation during the Zephyr build. At flash time, the bootloader will be flashed with the Zephyr image.

Nordic and STM32 SoCs can now use Segger's RTT protocol for console output, in addition to UART.

  • Controller support was added for the Nordic nRF52810.

A new Bluetooth Mesh node sample was added in samples/boards/nrf52/mesh/onoff_level_lighting_vnd_app. It demonstrates several generic and light models.

The BLE controller Kconfig options were reorganized. CONFIG_BT_CTLR means that a controller is implemented, with additional options (currently just CONFIG_BT_LL_SW) selecting a specific implementation. This allows adding alternative controller implementations in the future.

If the Bluetooth device is neither an observer or has central role selected, the scan related code is excluded from the HCI core. This results in smaller image sizes for peripheral- or broadcasting-only roles.

A Kconfig option "CONFIG_BT_CTLR_CRYPTO" was added to allow flexibility in choosing to use host cryptographic functions or the ones provided by the BT controller.

  • A new "shields" configuration was added to establish connector flags for compatibility checks. Arduino compatible serial, I2C and SPI were the first shield compatibility additions, with ST's nucleo_f429zi board making use of them. Expect more on this front as time goes on.

Several new boads were added: i.MX's UDOO Neo Full SBC and ST's STM32F746G-DISCO, STM32F723E-DISCO and STM32F769I-DISCO.

The I2C ports of several nRF-based boards were enabled.

  • An LLVM backend and a clang toolchain variant were added to support building with llvm (included with many popular Linux distributions). Initial testing was done on quark_d2000_crb and quark_se_c1000_devboard/Arduino 101. To enable this, set ZEPHYR_TOOLCHAIN_VARIANT to "clang" in your environment.

Architectures, boards, and apps can now override the C standard version, which was previously set to -std=c99. Currently, the native POSIX port uses this feature in boards/posix/native_posix/CMakeLists.txt, like so:

set_property(GLOBAL PROPERTY CSTD c11)

Device Tree:
  • Nordic boards moved I2C enablement, SDA and SCL pin configuration, and LED / button definitions into DTS.

STM32F7-pinctrl added definitions for USART/UARTs.

  • Information about the websocket server API was added to Zephyr's documentation. For details, see:


Intel S1000 developers will be happy to note that the docs now include instructions for obtaining the toolchain from:


As part of Zephyr's security development process, certain external requirements require justification that threats in a threat model have been mitigated. To make this process traceable, the threats must be enumerated and given labels. For this purpose, labels were added to the threats in Zephyr's sensor threat model. See the model itself for more details:


Ever wonder how DTS relates to Kconfig options? Wonder no more! Some clarification was added to the Device Tree documentation:


The "Getting Started" document did not clearly state how to use a custom cross compiler. This was remedied with a new section "Using Custom Cross Compilers". For details, see:


Information on the newly-supported gPTP protocol was added to the networking documentation.

  • STM32F2 and STM32F7 received clock_control, flash, GPIO, pinmux, UART, entrophy and interrupt_controller drivers.

The native POSIX Ethernet driver now has support for gPTP.

A generic I2C EEPROM slave driver was added.

USB drivers received several additions, such as high- speed support for DesignWare USB controllers, and an API for USB BOS (Binary Object Store) descriptors.

USB HID payload size is now configurable via CONFIG_USB_HID_MAX_PAYLOAD_SIZE (the previous value of 64 is still the default).

Shims for nRFx TWI, TWIM and PWM drivers were added and the now redundant i2c_nrf5 shim was removed.

A PTP clock driver was introduced which can be implemented in those network interface drivers that provide gPTP support.

An LED driver for NXP PCA9633 (I2C 4-bit LED) was added which supports a blink period from 41ms to 10667ms and a brightness value from 0 to 100%.

  • The NXP iMX6 FreeRTOS BSP was imported to add Zephyr support on iMX6SX processors (exclusively on the Cortex M4 core), and to speed up the development process.

The Nordic nRFX HAL was updated to support the nRF52810.

STM32cube updates for all STM32 families (including the addition of STM32F2x HAL) were also merged.

The Segger RTT debug code was updated to version 6.32d.

MCUMGR external sources were updated to external commit a837a731 from the upstream repository, available here:


  • Back in Zephyr 1.12, the old scheduler's thread queueing code was replaced with the choice of a "dumb" list or a balanced tree. The old multi-queue algorithm is still useful in some use cases, such as applications with large-ish numbers of runnable threads that don't need or want fancy features like EDF or SMP affinity. To fill this gap, the old implementation was reintroduced, and can be enabled using CONFIG_SCHED_MULTIQ.
  • The logging subsystem saw many new features merged, including: support for multiple backends, improving real-time performance by deferring logging to a separate runtime context, timestamps, and filtering options (which are compile time, runtime, module level, instance level). The console backend was added as the first backend example.
  • gPTP (Precision Time Protocol) support was added to according to the IEEE 802.1AS-2011 standard. To enable it, use CONFIG_NET_GPTP. Note: at this time, gPTP is only supported for boards that have Ethernet ports which support collecting timestamps for sent and received Ethernet frames. A gPTP sample was added at samples/net/gptp.

Also new to Zephyr is the LLMNR (Link Local Multicast Name Resolution) client and responder from RFC 4795. LLMNR is used in Windows networks. A caller can be set up to resolve DNS resource records using multicast DNS, as well as configured to listen for LLMNR DNS queries and respond to them. Related Kconfig options are CONFIG_LLMNR_RESOLVER and CONFIG_LLMNR_RESPONDER. The implementation is in subsys/net/lib/dns.

  • Socket API-based samples for echo_client and echo_server were added to Zephyr as well as a simple logger sample illustrating the new capabilities of the logger subsystem additions.

LLMNR client support was added to the DNS resolver sample.

A sample application for testing the NXP PCA9633 LED driver was added.

  • The Kconfiglib project in Zephyr saw a couple of updates:
  1. Dependency loop detection. Until now, dependency loops have raised a hard-to-debug Python RecursionError during evaluation. Now, a Kconfiglib exception is raised instead, with a message that lists all the items in the loop.

  2. MenuNode.referenced() was converted to a property, making the API more consistent (read-only values are accessed with properties).

  3. Warnings for choice overrides were eliminated.

The nrfjprog runner script was updated to accept a --snr parameter specifying the serial number of the device to be operated on.

Device tree now allows the use of a new element of DTC grammar called overriding nodes. It looks like this in a board's dts file:

arduino_i2c: &i2c1 {};

This overriding node information is used during the DTS include file generation like so In this way, ARDUINO_I2C_LABEL could be used as a generic binding name. This change is derived from a dtc commit in version v1.4.2.


  • The ARM/NXP MPU code was cleaned up a bit to avoid configuring out-of-bound MPU regions. Also, the ARM MPU code had several Zephyr defines replaced with direct uses of CMSIS defines.

When compiling, both cortex-m0 and cortex-m0plus will now use -march=armv6s-m instead of -march=armv6-m to to ensure the svc instruction exists.

  • Bluetooth Mesh now depends on CONFIG_BT_BROADCASTER and CONFIG_BT_OBSERVER, as they are necessary to implement Mesh devices. Several other Mesh-related bugfixes landed to solve initialization order during node reset, redundant model publication clearing, cyclic rewriting to flash when restoring state, checking for a model subscription address, and ignoring prohibited element addresses.

For the Bluetooth Controller core, LE Extended Scanner Filter Policy now depends on CONFIG_BT_OBSERVER and the time to transmit an empty packet was raised from 40 microseconds to 44 microseconds on a 2M PHY, due to an additional byte of preamble.

The BlueNRG-MS HCI driver received a pair of changes. In the first, it now reads from the controller as long as the IRQ is high. In the second, it makes sure to configure the BlueNRG-MS to controller mode just after it's ready by disabling "HCI reset" via a quirk.

  • The BlueNRG-MS Bluetooth configuration had to be fixed on the disco_l475_iot1 board. This includes SPI3 usage, SYSCLK adjustments, and a few build warnings.
  • The gen_isr_tables script received several updates for simplification and dead code removal.

Python script "process_gperf.py" used in the Zephyr build system will now be invoked via "python" instead of called directly. This avoids non-portable shebang logic and/or "default application" behaviour on Windows.

Device Tree:
  • STM32F4 saw corrected pin assignment of node usart6@0.
  • RTC syscall changes required a build error fix.

A build error was addressed for intel_s1000 which uses DesignWare USB. It doesn't inherit a qmsi header which has several definitions used in the driver. Instead those definitions are provided via a DesignWare specific header.

A build error in uart_handler.c was fixed when CONFIG_UART_LINE_CTRL is defined.

Fixes were applied to the nRF UART driver for broken hardware flow control and interrupt driven APIs.

For the USB/DFU subsystem, bcdUSB had been previously updated from 1.1 to 2.0 in the default device descriptor, but not in the DFU class. After USB bus reset performed by dfu-util, this alternative descriptor registered with bcdUSB was set to 1.1. This mismatch caused a communication failure. The DFU descriptor's bcdUSB was updated to match the default value.

The STM32 clock control driver received a fix to HCLK calculation when using MSI. The MSI clock signal can be selected in several ranges. These ranges should be taken into account for calculating its frequency and hence global system frequency. This change is used when enabling Bluetooth on the disco_l475_iot1 board.

A long-standing issue where the K64F-FRDM board would generate a random MAC address on every boot (which would lead to DHCP address exhaustion) has been solved. The existing Kconfig option CONFIG_ETH_MCUX_0_RANDOM_MAC, which dynamically chooses a random MAC address, is now one choice among many in the new CONFIG_ETH_MCUX_0_MAC_SELECT option. The other choices are CONFIG_ETH_MCUX_0_UNIQUE_MAC (the new default), which uses the MCU unique identification register to generate a stable MAC address which is persistent over reboots, and CONFIG_ETH_MCUX_0_MANUAL_MAC, which allows setting a fixed MAC address. For details, see:


NETUSB and STM32 ethernet hardware apparently never called ethernet_init(). This was revealed when the net_arp_init() function was moved into ethernet_init() and ARP tables stopped being initialized correctly, and has been fixed.

  • PWM related nrfx_config entries for nRF52840 were merged.

For STM32F4xx and STM32F7xx, the I2SR field needed to be shifted by RCC_PLLI2SCFGR_PLLI2SR_Pos when the PLLI2SCFGR register is read or written. Previously, the configuration was not done properly (R and M params were badly set) and the PLLI2S was generating a bad clock waveform.

  • The "net app" layer has historically been the combination of 2 separate but useful parts: 1) a library to set up client and server connections (CONFIG_NET_APP) and 2) a library to set up/configure networking on application startup (CONFIG_NET_APP_SETTINGS). As this second functionality is useful in almost every circumstance, it has been split out into a new top-level networking library under subsys/net/lib/config. In the future, this would also allow other networking frameworks such as sockets to use these configuration options. This move will cause issues for out of tree patches to the net app layer.

The layer 2 networking code was also moved as having it under subsys/net/ip/l2 didn't make much logical sense. The new location is subsys/net/l2. Hopefully, this movement didn't result in any functional changes, but only time will tell. Developers should note that any out of tree patches to the old layer 2 location will need to be refactored.

Zephyr's ARP table implementation was cleaned up slightly and optimized for memory usage through the use of a single linked list, smaller ARP entries, and handling request timeouts in a single k_delayed_work structure.

  • Several changes were applied to the Bluetooth Mesh nRF52 on/off level lighting sample at samples/boards/nrf52/mesh/onoff_level_lighting_vnd_app.

The 96 Boards ArgonKey sample added support for the TI LP3943 LED controller to test the 12 on-board LEDs.

  • The extract_dts_includes script was refactored for better maintainability; some false information messages were also removed.

hawkBit and MQTT sample application


  • Not addressed in this update


  • Not addressed in this update

LWM2M sample application


WCN14A2A support as modem-overlay.conf:
  • Support for the WCN14A2A LTE-M modem was refactored into a configuration fragment file named modem-overlay.conf.


Stack overflow fixed with DTLS enabled:
  • An overflow of the network management stack observed with DTLS enabled has been fixed by increasing its stack size to 1024B in that configuration.

Linux microPlatform


No significant changes have gone into this update. The previous update included updates to containers and the sources weren't published. The URL used for authentication in lmp-device-register was updated.


  • lmp-device-register updated to use app.foundries.io.
  • Updated sources of published containers.


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