Persisting connected USB devices
The following external hardware is connected to hangdevice
|Device||ID Vendor:ID Product||iSerial||Product|
|2||046d:082d||EF9B0F4F||Logitech, Inc. HD Pro Webcam C920|
|5||1209:8087||Generic MisfitTech Nano Zero #B Axis|
|6||1209:8087||Generic MisfitTech Nano Zero #C Axis|
|7||1209:8087||Generic MisfitTech Nano Zero #D Axis|
Problem: Vendor ID and Product IDs are the same for each Smart Stepper. So they cannnot be assigned by Serial ID. The solution is to use devpath instead of Product ID and Vendor ID. The following USB port mapping was found for my Raspberr Pi 3B (browsing on the web this seems to be indivually different for each Raspberry Pi). You also can change the IDs by re-flashing the Smart Steppers. See Smart Stepper - flashing the firmware for details.
Overview of busses, ports, devices
USB ports are sometimes confusing.
Mapping looks like this
Troubleshooting USB errors
A lot of different USB errors can occure (like "device not accepting address"). Most times a reset of the USB hub helps. We can turn off, keep off some seconds and turn on again the hub to re-init the devices in case there are no powering issues. See https://paulphilippov.com/articles/how-to-fix-device-not-accepting-address-error. See Smart Stepper - USB, Soft and hard reset for some tested out handling methods (works for webcam too).