CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Income Statement [Abstract]
Revenue	$ 12,149	$ 11,421	$ 18,956
Cost of revenue	6,627	7,648	11,411
Gross profit	5,522	3,773	7,545
Operating expenses:
Research and development	9,572	12,265	14,144
Selling, general and administrative	9,900	10,310	10,619
Restructuring costs	0	0	295
Loss from operations	(13,950)	(18,802)	(17,513)
Interest expense	(115)	(175)	(82)
Interest income and other expense, net	21	(106)	(107)
Income (loss) before income taxes	(14,044)	(19,083)	(17,702)
Provision for income taxes	87	65	146
Net loss	$ (14,131)	$ (19,148)	$ (17,848)
Net loss per share:
Basic (in dollars per share)	$ (0.18)	$ (0.29)	$ (0.32)
Diluted (in dollars per share)	$ (0.18)	$ (0.29)	$ (0.32)
Weighted average shares:
Basic (in shares)	77,291	65,377	56,472
Diluted (in shares)	77,291	65,377	56,472