If there is one debt you do not want to leave off your BK petition, it is pre-filing HOA dues. HOA's are pricks in the first place, so the last thing you want to do is give them any ammunition.
Having said that, was your chapter 7 case an asset or no asset case. If the case was no asset, then the pre-BK dues are "arguably" discharged even if the HOA did not receive notice.
Assuming you had a no asset chapter 7, send them a copy of your notice of BK filing, a copy of the discharge, and the bill showing the HOA dues you believed are discharged, and a cease and desist letter. However, if the HOA persists, then you should get with a BK attorney to explore your next steps.
As a general rule, unless the trustee distributed assets to unsecured creditors, the pre-petition debt should be discharged (unless they had/have a separate basis for nondischargeability - which seem unlikely with HOA dues). [Feel free to Google "In re Beezeley".]
As to the post-petition HOA fees, Section 523(a)(16) of the Bankruptcy Code exempts from discharge any "fee or assessment that becomes due and payable after the order for relief to a membership association with respect to the debtor's interest in a unit that has condominium ownership, in a share of a cooperative corporation, or a lot in a homeowners association." So, they are not discharged. Technically, they can sue you. However, you might try to talk them into not bothering since they might be paid in a foreclosure (depending on their lien priority).
My answer is general information not intended to create an attorney-client relationship. Seek advice from a qualified attorney to see how the law fits your specific facts. If you are in Washington or Oregon, please feel free to contact us to see if we might be of assistance.
I am going to assume for the sake of simplicity that you had a no-asset chapter 7, since this is the case in most chapter 7s. Pre-filing dues will have been discharged; if they argue, have your bankruptcy attorney send a letter over with the discharge order. Everything that has accumulated since date of filing is your responsibility. In other words, when your HOA sues you, you will lose. You are probably on the hook for their "costs of collection," including attorney fees, as well. Your best option may be to pick up the phone and arrange a payment plan where you will pay monthly dues and a portion of the late dues. It sounds like you are not paying your mortgage, so you should consider this the cost of staying in the condo.