Note 8 - Stock-based Compensation - Schedule of Allocation of Recognized Period Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Total costs and expenses	$ 202	$ 741	$ 570	$ 343
Cost of Sales [Member]
Total costs and expenses	18	31	54	43
Research and Development Expense [Member]
Total costs and expenses	82	486	239	22
Selling, General and Administrative Expenses [Member]
Total costs and expenses	$ 102	$ 224	$ 277	$ 278