– Download and run the latest version of Zadig
– From the Zadig interface select Options and choose List All Devices
– From the Dropdown list of devices select CP2102 USB to UART Bridge Controller and click on Replace Driver with the WinUSB driver selected
– If you have multiple 5-chip GC3355 DualMiner USB devices connected you may need to repeat the procedure for all of them
– Download, edit and run LTC_ONLY.bat file from the modified cgminer 3.7.2 for Gridseed ASICs to start mining for LTC
It seems that there are some ASIC devices that may be using different virtual USB to COM drivers other than the CP2102 that our unit has (for example ST32 Virtual COM Port), unfortunately we don’t have any of those to test with. You can however try to make things work by replacing the other driver with WinUSB, just select the right name from the dropdown box (do not try to rename drivers, it is pointless) and Replace it with WinUSB (you may need to unplug and plug the USB cable to the miner after that). If after installing the WinUSB driver over the virtual USB to COM driver the ASIC does not work with cgminer, you just need to uninstall the driver from the Device Manager and unplug/plug the USB cable to the device for it to install the original USB to COM driver and it should be functioning again with cpuminer (note that this way you may have it running on a new COM port).
Do note that if running single Gridseed ASIC device you can have it connected to the system and use the hotplug 0 option, if you have more than a single miner you may have to set commandline option hotplug to 5 or 10 and then run cgminer and start plugging the USB cables of the miners (USB hubs with power on/off buttons work great for that).