iCE40 Ultra/UltraLite: How to resolve "Failed in Function NVCM_ENABLE" error during programming?
Two ways to resolve this is by:
1. Double check and try to interchange the TDI/SI and TDO/SO wires of the HW-USBN-2B cable.
2. If you are using a custom board, please check if you have followed the correct Power-up Supply Sequence mentioned in our datasheet. Please check pages 20 and 21 of DS1050 document.