I'm Pops, one of the Community Managers at Stack Exchange. We on the SE team announced some changes to graduation a few months ago that applied across the network. Those of you who follow such things may be wondering how Arduino SE is doing in the "new system," so I'm here to give you an update based on a recent CM evaluation.
tl;dr: Arduino has been doing pretty well! There's a lot of good information in the Meta SE post I linked above, but the most important point with respect to graduation is this: our primary criterion for evaluating sites is now the number of new questions received per day. You're bouncing around ten questions a day (sometimes less, but sometimes more), which we consider pretty strong.
With that said, we're still not quite ready to consider you graduated. The primary reason is the lack of high-reputation users on the site. Although we're currently making some changes to the processes of graduation, all fully graduated sites will ultimately still have their reputation requirements for various privileges (e.g. editing, voting to close, voting to delete) increased from public beta levels, as described here.
As I write this, Arduino SE isn't home to a single user with 10k or more reputation points, which means that nobody would be able to vote to delete or undelete posts after the change in privilege levels; your total number of users with at least 3000 rep is barely enough to agree to close any question; and there aren't that many more at 2000 rep, who would be able to edit. Community moderation is an integral part of the design of Stack Exchange sites, so we really need to see more users who would be able to take those actions to consider the site for graduation.
Aside from reputation, there are a couple more minor concerns. For one, your "percent answered" rate is among the lowest in the network, which has been addressed here on meta before. However, all of the "worse" sites are either already graduated or special cases, and the community discussion about the problem — though sparse — has led to at least one good potential solution.
The other issue is that the scope of this site doesn't seem to be 100% set yet. Just a couple weeks ago, there was a moderately popular proposal to merge this site with a few others, and the friction with EE about where to ask hasn't completely dissipated. We're not too concerned about this, since Arduino is a fairly well-defined topic, but you as a community do need to decide soon whether you want to make any major changes, because after graduation is too late.
I hope this rundown has been useful for you. If you have any ideas or comments, leave 'em below!