Note 14 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 5,479	$ 5,686
Deferred Tax Assets, Valuation Allowance, Total	8,313	$ 7,878
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Deferred Tax Assets, Net, Total	8,039
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	35,819
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	1,262
Deferred Tax Assets, Tax Credit Carryforwards, Research	2,373
State and Local Jurisdiction [Member]
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 176