Note 10 - Shareholders' Equity - Fair Value Assumption of Warrant (Details) - $ / shares		12 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2020	Jun. 30, 2017
Warrants issued (in shares)		5,830,000	500,000
Exercise price (in dollars per share)	[1]	$ 0.75	$ 0.54	$ 0.75
Warrant [Member]
Weighted average fair value (in dollars per share)		$ 0.51	$ 0.41
Warrants issued (in shares)		5,830,000	500,000
Expected term (in years) (Year)		5 years 182 days
Risk-free rate		2.74%
Volatility		102.73%
Warrant [Member] | Minimum [Member]
Exercise price (in dollars per share)		$ 0.75	$ 0.01
Expected term (in years) (Year)			2 years
Risk-free rate			1.62%
Volatility			60.00%
Warrant [Member] | Maximum [Member]
Exercise price (in dollars per share)		$ 0.9375	$ 0.54
Expected term (in years) (Year)			3 years
Risk-free rate			2.55%
Volatility			82.00%

[1] Weighted average exercise price per share.