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network.USBD_NCM arrived upstream in 1.29: deliver it as a costume, or record the exclusion #21
Description
MicroPython 1.29 adds network.USBD_NCM (Ethernet-over-USB as a USB device class; extmod/network_usbd_ncm.c, documented under network), off by default. usbif's costume roster is the org's statement of which USB device classes a board can wear, and it says nothing about NCM either way.
The pin-move checklist (micropython-pydevices#1) asks for one of two outcomes, and this issue is where it gets recorded:
- Deliver it: a costume that enables
USBD_NCMalongside (or instead of) the existing classes, with the descriptor policy usbif's extension header already applies, proven on the S3 and the P4 the way the other classes were. - Exclude it: a line in the roster saying NCM is upstream's own class, reachable by enabling it in a board's config without usbif, and why usbif does not wrap it.
Nothing is broken today; the class is simply unaccounted for. Found in the post-pin-move sweep, 2026-09-23.
Activity
bdbarnett commentedon Sep 26, 2026
Still unaccounted for on 1.29. Nothing in the README, docs, src or examples mentions NCM.
One thing to weigh: usbif serves the configuration descriptor itself. #26 shows that
machine.USBDevice's runtime interfaces never reach the host on a usbif image, andnetwork.USBD_NCMvery likely hits the same wall. So "reachable without usbif" would really mean "on an image built without usbif".@bdbarnett: deliver it as a costume, or record the exclusion? I'd record the exclusion for now: one roster line saying NCM needs an image without usbif. Build the costume when someone actually wants Ethernet over USB.
bdbarnett commentedon Sep 26, 2026
Brad's decision (2026-09-26): parked. The NCM (Ethernet over USB) costume waits until something in the program needs a wired-over-USB link. That's the trigger.
bdbarnett commentedon Oct 7, 2026
Planned now in ROADMAP.md: https://github.com/PyDevices/usbif/blob/main/ROADMAP.md