Posts Tagged ‘Lightningasic DualMiner


When we’ve made our previous guide for dual mining BTC and LTC on a Gridseed 5-chip GC3355 ASIC we’ve only had an earlier revision of the miner that used CP2102 USB to UART Bridge Controller. Now that we already have a newer revision with the STMicroelectronics Virtual COM Port we have decided to update the guide with information on how to Dualmine on these ASIC devices. Note that we do not recommend using these devices for dual mining mode, but for Scrypt only mode instead, but you are free to decide for yourself. The advantages of using Scrypt only mode are the low power consumption and heat, the ability to overclock higher, including with a voltage modification and a choice of multiple more up to date software miners. Note that the only way for the moment to use the Dual Mining mode on the Gridseed 5-chip GC3355 ASIC devices is to use the special version of cgminer 3.8.5 for BTC mining (SHA-256) along with the special modified version of cpuminer for Gridseed for LTC mining. Due to the way that the Dual Mining mode is realized on these ASICs using a more recent version of cgminer or bfgminer for LTC (Scrypt) mining on these devices along with the cgminer for BTC mining is not possible at the moment.


– Open up Windows Device Manager and go to the Ports (COM & LPT) and note the COM port that is written behind the STMicroelectronics Virtual COM Port driver
– 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 STM32 Virtual COM Port and click on Replace Driver with the WinUSB driver selected
– Download the dualmining package that we have prepared for windows that contains cgminer 3.8.5 for BTC mining and cpuminer for LTC mining
– Edit the BAT files for the two software miners included in the archive with your settings for BTC and LTC mining pools
– In the LTC-START.bat file you will see an option “gc3355=\\.\COM4”, here you need to change the COM port number to the one you have seen in the device manager before updating the driver with Zadig to use WinUSB
– First you need to start cgminer 3.8.5 for BTC mining, wait a few seconds until the software starts up and connects to the pool and starts working
– Then start the cpuminer for LTC mining, note that you will need to wait for some more time here before the miner connects and starts working, but it it takes more than a minute maybe something is not right

If you still haven’t used cpuminer for Gridseed you should know that the software does not report local hashrate, so the zeroes you see are normal, it is actually working and sending shares. Also note that when in Dual Mining mode you will not be able to overclock the device as high as when only in Scrypt mining mode, so it is normal to be getting lower hasrate. As we’ve already said, we do not recommend the Dual Mining mode and suggest to use these ASIC devices for Scrypt mining mode only, especially if you want to run multiple devices.

Download the DualMining package for BTC/LTC mining on Gridseed 5-chip GC3355 ASIC for Windows…


In our article about our first impressions from the Gridseed 5-chip Scrypt Asic earlier this month we were not very happy with our initial experience from the device. It seems we’ve got one of the earlier builds that were not very well built and the software for using them was also at a very early stage. Today however things look much better, we just got a new unit that we have ordered and it is much better built and uses the STM32 Virtual COM port driver instead of the CP2102 USB to UART Bridge Controller that our previous unit had.


We have tested the new ASIC device and it works just fine with the STM32 drivers installed with the modified for low power usage cpuminer for Scrypt mining by giving the virtual COM port number of the device. The ASIC also worked just fine when we have replaced the STM32 vitual cOM Port driver with WinUSB using Zadig to use cgminer 3.7.2 for Scrypt mining on the ASIC. We still haven’t tried using the new 5-chip Gridseed ASIC device to work in dual mining mode with TLC and BTC mining running at the same time as apparently the dual mining method that have already described for our older ASIC using the CP2102 USB to UART Bridge Controller is not working for devices with STM32 Virtual COM port drivers, so we’ll be getting back with more details on that later on when we figure it out.

For the moment however we are much more satisfied with the newer revisions of the 5-chip Gridseed LTC/BTC ASIC devices, especially when we take into account the improvement of the software support side for them in the last few days.


The 5-chip Gridseed GC3355-based ASIC devices that support Dual Mining for Bitcoin and Litecoin are not that easy to be used in the Dual Mode, because you need to have two different software miners running at the same time. There is a bit of specifics in what and how you need to do in order to mine both BTC and LTC at the same time and after a bit of tinkering we have managed to finally make things work as they should under Windows. You need to download a special modified version of cpuminer for Scrypt (LTC) mining and a modified version of cgminer for SHA-256 (BTC) mining. We have compiled the two software miners and you will find the download links below. You will also need the Zadig software in order to replace the virtual USB to COM driver with WinUSB driver for the cgminer to detect and work with the BTC mining side of the ASICs.


– 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 the BTC.bat file from the modified cgminer 3.8.5 for the Gridseed ASICs to start the miner working on BTC
– Download, edit and run LTC_ONLY.bat file from the modified cpuminer for Gridseed ASICs to start mining for LTC (check what your COM port is and edit it). You need to add the parameter “dual” (without the quotes and two dashes in front) to the command line in order for the Dual mode mining to start working

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).

This is it, you should have the miner running both SHA-256 (BTC) and Scrypt (LTC) mining withe the two software miners and the total power consumption should be about 60W. Note that you may need to lower the operating frequencies a bit for when mining the Dual BTC/LTC mode as the chips get hotter. If you want to mine only BTC you can stick only with running the modified cgminer, for LTC only you need the modified cpuminer without the dual option in the command line. The most attractive aspect of the Gridseed 5-chip GC3355 ASIC however remains their very low power consumption for Scrypt mining only mode, so think again if you really wan to run them in the Dual Mining more or for BTC only and not in LTC only mining mode instead.