| Note 8 - Goodwill and Intangibles | 3 Months Ended | 
|---|---|
| Dec. 31, 2020 | |
| Notes to Financial Statements | |
| Goodwill and Intangible Assets Disclosure [Text Block] | Note  8.Goodwill and Intangibles The Company analyzes its goodwill for impairment annually or at an interim period when events occur or changes in circumstances indicate potential impairment. The result of the analysis performed as of   September 30, 2020 did notindicate an impairment of goodwill. During the threemonths ended  December 31, 2020, there were notriggering events that indicate potential impairment exists. The Company capitalizes legal costs incurred to obtain patents. Once accepted by either the U.S. Patent Office or the equivalent office of a foreign country, these legal costs are amortized using the straight-line method over the remaining estimated lives,  notexceeding 20years. As of  December 31, 2020, the Company has 26patents granted and multiple pending applications both inside and outside the United States. In addition, the Company has various finite lived intangible assets, most of which were acquired as a result of the acquisition of the active cabinet product line from Calix, Inc. during fiscal year  2018.The Company analyzes its intangible assets for impairment annually or at interim periods when events occur or changes in circumstances indicate potential impairment. The result of the analysis performed as of  September 30, 2020 did notindicate an impairment of our intangible assets. During the threemonths ended  December 31, 2020, there were notriggering events that indicate potential impairment exists. |