Note 12 - Equity Transactions and Stock-based Compensation - Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range (Details) - $ / shares	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Range of Exercise Price, Lower Limit (in dollars per share)	$ 0.09
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.25
Outstanding (in shares)	3,344,000	3,761,500	2,439,250
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.16	$ 0.16	$ 0.29
Weighted Average Remaining Contractual Life (Year)	7 years 255 days
Exercisable (in shares)	2,875,533	2,863,800
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.16	$ 0.14
Range One [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.09
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.10
Outstanding (in shares)	1,386,000
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.09
Weighted Average Remaining Contractual Life (Year)	4 years 328 days
Exercisable (in shares)	1,386,000
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.09
Range Two [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.21
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.21
Outstanding (in shares)	1,408,000
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.21
Weighted Average Remaining Contractual Life (Year)	8 years 328 days
Exercisable (in shares)	1,022,867
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.21
Range Three [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.23
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.25
Outstanding (in shares)	550,000
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.23
Weighted Average Remaining Contractual Life (Year)	6 years 146 days
Exercisable (in shares)	466,666
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.23