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111 Picoseconds Later — Zephyr Podcast #058

By November 6, 2026No Comments

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

Episode Summary

  • STM32G5: ST announced the STM32G5, a Cortex-M33 series running at up to 280 MHz for digital power and motor control, and a pull request adding Zephyr support went up the same day, with clock control, GPIO, UART and RTC on the NUCLEO-G564RE. Its high-resolution timer has 111 ps resolution, used to stagger the phases of multiphase power converters, and the series also has a 5 MSPS ADC, a position encoder block and a small programmable logic array.
  • nRF71: Nordic announced the nRF71 series, its first SoC with Wi-Fi on chip, where the nRF70 was a companion chip: a 256 MHz Cortex-M33 with a RISC-V coprocessor, 4 MB of non-volatile memory and 1 MB of RAM, Wi-Fi 6 on 2.4 and 5 GHz, and a separate 2.4 GHz radio for Bluetooth LE, Thread and Zigbee. The nRF7120E adds 6 GHz (Wi-Fi 6E) and an NPU. It only comes in a WLCSP package, and Zephyr already has an nRF7120 DK board.
  • AI Reviews: A pull request wires the Zephyr review agent into CI. Add the ai-review label to a pull request, and the agent, run by the project with instructions geared to Zephyr’s guidelines and architecture, posts a summary and inline comments, flagging what’s a nit and what must change. A cheap model does a first pass, and a more capable one goes deeper when needed. Its reviews neither approve nor block a pull request; whoever requested the review follows up on the findings. Everything, prompts included, is public, so gaps can be fixed in the open, and you can run it locally with your own API keys. It has been running manually on pull requests for the past couple of weeks; share your feedback on Discord.
  • Subsystem Skills: Beyond reviews, short per-subsystem guidelines, or skills, could tell agents what each subsystem expects, whether they’re writing or reviewing code: for example, which API an input driver should use for deferred interrupt handling.
  • heatshrink: heatshrink, an LZSS compression library for embedded systems with low memory use and predictable CPU usage, can now be used as an external module, following the instructions in the docs.
  • Bitmaps: Johan Hedberg added a non-atomic bitmap API: SYS_BITMAP_DEFINE() declares a bitmap of any size, with sys_bitmap_*() helpers to set, clear, test and search bits. With no locking, it’s lighter than atomic bitmaps when the owner already serializes access.
  • GPIO Straps: A new OTP GPIO strap backend exposes strap resistors, typically used to encode a board’s hardware revision, as read-only OTP memory described in devicetree, so firmware can read the revision through the OTP API. Each pin is disconnected after it is read, to save power.
  • native_tty: Two native_tty improvements from Otavio Salvador: a low-latency property that sets the host tty’s low-latency flag (on FTDI adapters, 1 ms instead of 16 ms), and a usb-ids property that finds the right serial port by USB vendor and product ID, so a native_sim application can talk to a real device, such as a modem or a PLC, plugged into your machine.
  • I2C Target Registers: Fabio’s per-register callbacks for the I2C target register library, for read-only, clear-on-read or write-1-to-clear registers, are now merged.
  • Rapid Spanning Tree: Jukka Rissanen’s implementation of the Rapid Spanning Tree Protocol for the Ethernet bridge lets devices with two Ethernet ports be chained in a ring: RSTP blocks one link to avoid a loop, and re-enables it if another link goes down, converging in well under a second where classic STP takes tens of seconds. On an i.MX RT1170 EVK, failover took under 300 ms.
  • Tightly Coupled Memory: The NXP FRDM-MCXE32B has a dual Cortex-M7 MCXE32B with 4 MB of flash, 320 KB of SRAM plus 192 KB of tightly coupled memory, CAN FD and Ethernet. Placing hot code in TCM makes a big difference, and Zephyr can relocate code there, but what fits depends on each part, which makes it hard to do portably. If you have a good way to rank code by how hot it is and fill TCM accordingly, tell us.
  • XIAO Display Gadgets: Benjamin added the Seeed XIAO Display Gadgets as shields: 0.96″, 1.14″ and 1.47″ displays, the latter with touch, built around the XIAO nRF52840 Plus or ESP32-S3 Plus.
  • FOSDEM 2027: Submit your talks for the Embedded & Resource-Constrained OS devroom through the FOSDEM 2027 call for papers by 16 November.