@pdp8e p8e Happy to share! The best way to see what changed through each major revision is on the Github releases page for the Spark Core:
The version that we showed on the Kickstarter page was v0.1.0; the last version before production was v0.2.5, and the current version is v1.0 (although we haven’t generated a Github release yet).
Our release notes are pretty comprehensive so hopefully that’ll cover the reasons for the changes, but to quickly touch on our mindset at Kickstarter launch - when we finished v0.1.0 for KS, we knew that it would still need to go through RF (Radio Frequency) optimization and DFM (Design for Manufacturability) review (both of which are covered in the releases). Everything else we did either came from feedback from our backers or from our own experimentation.
As an example, we kept ripping the USB connectors off of our early revision Cores, so we switched the connector with a through-hole model so that it would have more stability.
We also switched from 2 LEDs for feedback to an RGB LED because there are many states that the Core goes through on its way to being connected to the Cloud, and it was very difficult to debug the state with just two LEDs. An RGB LED gives us lots of colors to showcase different states.
Hope that’s helpful!