Sounds like you are attaching to your rim joist.
You need a proper foundation. I'd go down at least 3 feet. Maybe more in AB. Use a sonotube and pour concrete. Put in post connectors in the wet concrete and attach your posts. You don't want the deck moving up and down from frost heaving. The connection to the rim joist will act like a hinge and might fail or introduce leaks or change the pitch. You're going to be spending a lot of money on this, don't go cheap on this aspect.
If you don't connect to the house, you could float it on deck piers that you buy at the home center, but your spans are less and I think they look like crap. I don't think you save any money either because you need so many.
Also, make sure you have a correct grade away from the house before building. Don't want water going toward the house.