Starling 2 Max: WiFi dongle USB link (error -71,) - dongle tested good on PC

[kristi]

Hardware: Starling 2 Max, SKU MRB-D0012-4-V2-C29-T9-M22-X0 (V2, T-Motor)

Software: voxl-suite 1.3.5, system image 1.7.10-M0054-14.1a-perf

Stock RTL8821CU WIFI dongle keeps dropping off the USB bus: "device descriptor read/64, error -71", "device not accepting address", and "usb usb1-port1: Cannot enable.

Fails with the aircraft untouched. Battery power-cycle revives it temporarily.

Same day, I tested this same dongle on a Windows PC: clean enumeration, 0% loss ping. Fine on PC, dies in 12 s on the drone

Is this a known issue?

[electroAJ]

Hi @kristi,

I'm experiencing a similar, though maybe not identical issue. Would you mind sharing the repeatability of your problem? is it consistent? thanks.

[kristi]

Hi @electroaj

It's intermittent but it's gotten worse over about three weeks. Dongle would vanished from the USB bus mid-session. And then at boot the dongle enumerated for under a second, then went into the device descriptor read/64, error -71 . No software path recovered adb reboot didn't help. Only a physical restart (unplugging and plugging back to power), would bring back now even that has been inconsistent. Sometimes it would last 30 minutes after physical restart sometimes just a few seconds.

[tom]

Hi @kristi ,

Not a known issue. error -71 on the descriptor read happens before the WiFi driver loads, and getting worse over weeks with only a power cycle recovering it points to a failing part in the USB path rather than software.

Working on a PC does not rule out the dongle, since we have seen these Alfa dongles fail in service
(https://forum.modalai.com/topic/4538).

On Starling 2 Max the dongle sits in the M0141 breakout on VOXL 2 J3, so the likely fix is replacing one of them:

1. Try a new AWUS036EACS or AWUS036ACS (https://docs.modalai.com/voxl-2-wifi-setup/).
2. If a new dongle fails the same way, open an RMA so we can inspect the board: https://www.modalai.com/rma

Posting voxl-version and dmesg | grep -i usb from a failing boot would help us confirm.