I'm trying to install the Digispark board from the url:
http://digistump.com/package_digistump_index.json
I entered it to the Optional Additional Boards field, pressed rescan, but nothing happens. The board is still missing on the bosrds list. Any ideas?

Hi,

After adding a json and clicking rescan the digispark package should then be available in the Board Manager list (not the usable boards list)

(bug) If you can't see the package in board manager after clicking Rescan then click one more time.

Once a package is available in the Board Manager you will then see a list of platforms it supports (sometimes only one but often more). Click the platform you want to install and that will download the platform from the correct www location.

After installing a package click the Rescan (twice to be sure) or restart the ide and the boards of the platform will appear in the boards list.

Some packages, such as arduino, have multiple platforms which is why they are not immediately available after adding the location of a .json file.

An alternative...

The Arduino IDE can also be used to install json and packages which Visual Micro will auto detect during restart of after clicking rescan. The Arduino IDE works the same way where you first register the json and then use Board Manager to install the required platform.

Hope this makes sense.

My bad, I wasn't using the latest version. I was on 1607.20 It's working now. Sorry for a false alarm.

Great, yes there have been lots of fixes and enhancements this year. It was a big change to add support for the Board Manager so took a while to mature.

Thanks for the update.