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An RTOS for Ages Two and Up — Zephyr Podcast #049

By September 4, 2026No Comments
The Zephyr Podcast, episode 049

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The summary below was automatically generated using the assistance of AI tools.

Episode Summary

  • A Synth That Doesn’t Run Zephyr: The episode opens on the Dato DUO, a two-sided open-firmware synthesiser marketed at ages three to 99, being eyed as a present for someone turning two. The firmware is on GitHub and the hardware is NXP plus a pile of ADCs, DACs and RGB LEDs, so a Zephyr port is at least imaginable. Teenage Engineering gets dragged in as further budgetary temptation.
  • pytest in Twister: Hardware-in-the-loop testing where the device under test needs a second board to simulate the world around it. Twister’s pytest harness flashes the image, then hands control to Python that can drive the shell, read back responses, and identify which board is which by serial number. You can run pure pytest tests, or keep ztest and trigger the cases from the ztest shell once the jig is ready.
  • The Project Keeps Growing: Around 500 unique people contributed code in the last month, and seven new Silver members joined: Canonical, Dojo Five, GigaDevice, Morse Micro, Northern.tech, Siemens and Space Cubics. Seeing large industrial companies go public about Zephyr is the interesting part.
  • Arduino Core for Zephyr 1.0: The Arduino core reached 1.0, so digitalWrite() and the rest of the familiar API sit on top of a Zephyr firmware, with existing Arduino libraries mostly just working. It tracks Zephyr 4.4.1, which is about as current as commercial adoption gets.
  • Maintainers Forum Agenda: The agenda for the Monday side event at ZDS is published: a full day, two parallel tracks, two-hour sessions on roadmap, safety certification and CRA, AI, clock management and more. Seats are limited.
  • Say SDO and SDI: A large but shallow change moves the SPI API to inclusive terminology: controller and peripheral instead of master and slave, SDO and SDI instead of MOSI and MISO. I2C did this years ago and SPI was overdue. Vendor datasheets and HALs will keep the old names for a long while, so expect to translate.
  • VirtIO I2C: The VirtIO I2C adapter driver is merged, with SPI still queued. The follow-up worth waiting for is wiring the QEMU x86 and Cortex-A53 boards so the VirtIO I2C controllers are configured out of the box and you can reach a host-side socket, and from there something like i2c-tiny-usb.
  • A Fifth Timeout Backend: The Pugh skip list backend joins the delta list, bucket, min-heap and wheel. Multi-level indices give O(log n) lookup that scales where a linear walk does not, and the PR comes with unusually thorough benchmarks of where each backend wins and what it costs in memory.
  • SDL Mouse Wheel: The SDL input driver now reports mouse clicks and the wheel, so a UI built for a rotary encoder can be iterated in native_sim instead of reflashing hardware for every pixel.
  • TFTP Shell: Shell commands for TFTP, needing a filesystem to land in. Trivial is the operative word: UDP, no flow control, and clients everywhere, which makes it a handy way to move small files on and off a device.
  • Applets: A proposed applet subsystem for sub-applications with their own lifecycle, start and stop hooks and optional memory domains. It can sit on llext for dynamically loaded binaries, or just on threads. It arrives with extensive docs and samples, and raises the question of how close Zephyr now is to dynamically loaded drivers.
  • Wi-Fi HaLow: S1G bands and 1/2/4/8 MHz bandwidths land in wifi_mgmt. Sub-1 GHz Wi-Fi trades throughput for range and wall penetration, and the patch was tested against a Morse Micro module, one of the week’s new members. European duty-cycle rules on 900 MHz make it a better fit in the US for now.
  • Boards: The UDOO KEY now supports its RP2040 as well as its ESP32, which makes the hammer-shaped board from two weeks ago twice as useful and no easier to solder to a carrier. Plus more Silicon Labs boards and SoCs.
  • Out and About: ROSCon in Toronto, where Zephyr’s robotics working group has been drawing a crowd, and six Zephyr meetups over the next month in Amsterdam, Zurich, Stuttgart, Moonachie, New Jersey, Munich and Bucharest.