Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Common Stock [Member]		Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2017	[1]	5,753,000
Balance at Dec. 31, 2017		$ 6	[1]	$ 268,907	$ (254,035)	$ 14,878
Common stock issued under stock plans and employee stock purchase plans (in shares)	[1]	105
Common stock issued under stock plans and employee stock purchase plans		$ 0	[1]	353	0	353
Common stock offering, net of issuance costs (in shares)	[1]	965,000
Common stock offering, net of issuance costs		$ 1	[1]	13,901	0	13,902
Stock-based compensation		0	[1]	1,901	0	1,901
Net loss		$ 0	[1]	0	(13,779)	(13,779)
Balance (in shares) at Dec. 30, 2018	[1]	6,823,000
Balance at Dec. 30, 2018		$ 7	[1]	285,062	(267,814)	17,255
Common stock issued under stock plans and employee stock purchase plans (in shares)	[1]	110,000
Common stock issued under stock plans and employee stock purchase plans		$ 0	[1]	(37)	0	(37)
Common stock offering, net of issuance costs (in shares)	[1]	1,314,000
Common stock offering, net of issuance costs		$ 1	[1]	8,001	0	8,002
Stock-based compensation		0	[1]	3,144	0	3,144
Net loss		$ 0	[1]	0	(15,444)	(15,444)
Common stock issued for SensiML acquisition (in shares)	[1]	84,000
Common stock issued for SensiML acquisition		$ 0	[1]	903	0	903
Balance (in shares) at Dec. 29, 2019	[1]	8,331,000
Balance at Dec. 29, 2019		$ 8	[1]	297,073	(283,258)	13,823
Common stock issued under stock plans and employee stock purchase plans (in shares)	[1]	121,000
Common stock issued under stock plans and employee stock purchase plans		$ 0	[1]	(24)	0	(24)
Common stock offering, net of issuance costs (in shares)	[1]	2,642,000
Common stock offering, net of issuance costs		$ 3	[1]	8,097	0	8,100
Stock-based compensation		0	[1]	1,739	0	1,739
Net loss		$ 0	[1]	0	(11,151)	(11,151)
Balance (in shares) at Jan. 03, 2021	[1]	11,094,000
Balance at Jan. 03, 2021		$ 11	[1]	$ 306,885	$ (294,409)	$ 12,487

[1] Common stock, par value and additional paid-in capital amounts are adjusted to reflect 1-for-14 reverse stock split effected on December 23, 2019.