I wanted to flash a SonOff USB Zigbee dongle to use it as a repeater (SonOff refers to this as flashing it to be a "router") on HE. These things are great Zigbee repeaters! After flashing them just plug them into any USB power supply that provides at least 0.5A at 5V. Most phone chargers would work.
Flash from Pi/Linux
I got a lot of help from @aaiyar on this guide. I documented the process and added some helpful info about the dongle in an "easy-as-pie" PDF for others like me who need more than the usual level of support to figure things out.
Instructions and links for flashing the "P/Plus" version w/the router firmware are in the PDF below. Enjoy. And thanks again to @aaiyar.
Remember, this guide is for the "P/Plus" version of the dongle, chip info from Amazon page on the P/Plus version:
Flash from Windows
If you prefer to flash from a Windows device, @jtmpush18 found and used this video guide to flash a P/Plus dongle successfully. Great option if you don't have a Pi or Linux device or prefer to use Windows.
E version of the dongle
There is also a newer "E" version using a different chip that is not covered in these guides (you'd use a similar process, but the required flashing software and FW file will be different):
See the next post in this topic for more info on the dongle and flashing.
12/11/2022 - Added info on a method to flash using Windows that @jtmpush18 provided. So now you can use Pi/Linux or Windows to flash your dongle. (Hey, not my fault that sounds funny... )
11/8/2022 - Confirmed that new dongle launchpad router FW 20221102 can be flashed using cc2538-bsl or uniflash 8.0.0 (not 8.1.0). More info in PDF.
11/2/2022 - New dongle launchpad router FW has been released, with ability to set transmit power. Default is still 9dbm (added in 20220125 FW). Updated PDF to the bin folder so that when new FW versions show up there will be a working link to the FW directory. Thanks to @jtmpush18 for notifying about the updated FW version. Changelog for the new FW includes " * Allow to set transmit power" so hopefully any issues will be resolved so we have easier access to transmit power setting.
10/25/2022 - Added link to second post to another discussion related to flashing the P and E dongles. That discussion also includes information about how to set the dongle transmit power. P evidently defaults to 5db, E defaults to 20db
10/18/2022 - Additional information on P vs. E version of the dongle, added more general information/links on the dongle to the second post.
10/17/2022 - Initial release