I realise that like everybody else Avidyne want all certified installations to be done by an Avidyne dealer, and they even told me (in writing but incorrectly!) that their STC is valid only for their dealers, but let’s say your situation is different e.g.
On the last option, a Garmin rep posted on a US site recently that there is a supported route for homebuilders, but here in Europe everything is much more complicated because of far fewer shops and much longer “comms links”…
Ideally one should be able to say “screw the warranty” and just get the firmware and load it from a laptop via USB.
If you have a good shop and a trustful relationship, they let you do Garmin updates yourself. It’s just a data card that can be sent via post.
That is Garmin. The IFD540 is Avidyne 
I found some info on a US site.
You go here and click here
There is a video which must be followed exactly otherwise you can brick the unit.
At one point the install may appear to stall when in fact it is doing some internal processing. Reportedly, Avidyne has consistently held the position that only an A&P signoff is is required and they aren’t forcing anyone to go back to a dealer.
You will need Avidyne to send you the install package which includes the mini SD card writer.
Obviously I have not tested the above because I don’t have this box yet, but my longer term plan is to get two of them.
In this case the unit must be opened, and the warranty sticker leaves “void”
As the dealer has new stickers, to ensure you keep warranty. The upgrade is performed under warranty by the dealer.
Reports from the USA say that the latest software bricks (crashes without any possibility of recovery, making the unit dead) the IFD540. One pilot bricked his #1 unit and then bricked his #2 unit, so he put the GNS530 back in.
Avidyne say they have a new loader which avoids this.
It may however be due to some ambiguity in the instructions.
So maybe wait for a little while…
