The Mac OS X app FireflyTool is used for production testing and programming. It can be used with the Firefly Ice Test Fixture or with an SWD cable. The advantage of the test fixture is speed. A PCBA without a battery can be pressed into the test fixture for a few seconds for testing and programming. As soon as it is complete you are immediately ready to move onto the next device.
Test Fixture Setup
Connect the parts in the following order:
FireflyTool
Download FireflyTool from GitHub in the firefly-production-tools repository. Start the FireflyTool and hold a PCBA in place to test and program.