Litecoin Mining on Mac OS X – DualMiner ASICs

When Litecoin was originally created, it was supposedly “GPU-resistant”: the Scrypt algorithm chosen and implemented would mean only CPU mining would be viable, keeping the network evenly distributed.

However it wasn’t long before folks had worked out how to tweak their GPU setups to allow them to run the Scrypt algorithm far more efficiently than a CPU. Some event claim that the creators of Litecoin knew this and mined the coin with GPUs from its inception. Either way, the viability of CPU mining for Scrypt started to take a serious dive in 2013.

“But Litecoin and Scrypt algorithms are still ASIC-resistant”, almost everyone claimed. The implementation required far too much high-speed memory to make it possible. Then, whispers on forums and websites started up in Q3 2013, talking about working Scrypt FPGAs and ASICs that were being developed overseas. And starting in January 2014 the devices began to materialize.

DualMiner U1 Front

The day is upon us folks. Scrypt ASICs are in the wild with next generation hardware already taking pre-orders. The first round of Scrypt ASICs come in two form-factors:

  • The 1-chip USB thumbstick sold and branded by DualMiner
  • The 5-chip Orb design sold by numerous resellers (without any noteable branding)

Both of these devices are powered by the GC3355 ASIC from GridSeed. This chip can hash both Scrypt and SHA and is even capable of doing both at the same time (hence the DualMiner name). The DualMiner U1 has a single GridSeed GC3355 chip clearly visible on the back-side of the device. It also features a physical dip-switch for toggling the device between 0.9V and 1.2V.


Unfortunately both the 1-chip and 5-chip devices came to market with their own custom software, meaning you could not mine with either the DualMiner or Orb miners with CGMiner or BFGMiner. You had to use either the reseller’s binaries or compile their custom software yourself, if the source was available.

The good news is that I have been actively working with several vendors of GridSeed hardware for the past couple of months on native support for both the 1-chip and 5-chip GridSeed ASICs in BFGMiner. CGMiner no longer supports any algorithm or coin other than SHA-2 and Bitcoin, so BFGMiner was the natural choice. And as of yesterday the DualMiner driver has been merged into BFGMiner so I can finally provide a proper walkthrough on OS X!

Miner Installation

As with many of the previous ASICs, DualMiner is currently only supported by BFGMiner. So, the first step is to install BFGMiner on OS X. There is a thread here on the Bitcoin Talk forums which discusses various ways to install bfgminer on Mac OS X. The most full-proof method is to use Homebrew:

  1. Launch from Spotlight or your Applications folder
  2. Install Homebrew by entering the following in the command prompt:
    ruby -e "$(curl -fsSL"
  3. Run the following command and then fix any reported issues:
    brew doctor
  4. Tap the following Homebrew repository so that you can install packages from it:
    brew tap nwoolls/xgminer
  5. Finally, install bfgminer:
    brew install bfgminer

Driver Installation

The setup here similar to BFL devices. Before mining you will need to install the Virtual COM Port Drivers from FTDI found here.

Because OS X has its own FTDI driver, under some circumstances you may need to manually unload that driver and load the official FTDI driver:

sudo kextload -b
sudo kextunload -b com.FTDI.driver.FTDIUSBSerialDriver


With the BFGMiner properly installed and the USB to UART driver installed, you can use the -d? argument to list available devices with bfgminer:

bfgminer -d? -S noauto -S dualminer:all --scrypt
[2014-03-21 19:08:16] Started bfgminer 3.99.0
[2014-03-21 19:08:17] Devices detected:
[2014-03-21 19:08:17] Device (driver=dualminer; procs=1; path=/dev/cu.usbserial-000050FDA)
1 devices listed

Note the additional --scrypt argument since we will be Scrypt mining. I’ve also included the -S noauto argument to prevent GPU detection (for simplicity).


Once the DualMiner U1 is detected you can start BFGMiner using the -o, -u and -p arguments to begin mining:

bfgminer -S noauto -S dualminer:all --scrypt -o hostname -u username -p password

DualMiner Scrypt Only

You can also over-clock the DualMiner U1 using BFGMiner and the --set-device argument. Currently the following rates are supported: 400, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, and 1200 (850Mhz is the default).

bfgminer -S noauto -S dualminer:all --set-device dualminer:clock=850 --scrypt -o hostname -u username -p password

The GridSeed chips also support Dual Mode mining: mining both SHA-2 and Scrypt at the same time. Note that with the DualMiner 1-chip device you should change the hardware dip-switch from L to B to lower the voltage. Doing this requires running two instances of the miner (BFGMiner in this case), one of them with an extra argument.

First, launch the SHA-2 miner instance:

bfgminer -S noauto -S dualminer:all -o hostname -u username -p password

DualMode SHA

Then launch the Scrypt miner instance with the --set-device argument:

bfgminer -S noauto -S dualminer:all --set-device dualminer:dual_mode=1 --scrypt -o hostname -u username -p password

DualMode Scrypt

Note that, as seen above, running in Dual Mode will result in a slower Scrypt hashrate: approximately 30Kh/s rather than 70Kh/s.

If you have any questions feel free to post them in the comments below or on this thread at the Bitcoin Talk forums. And now, happy Scrypt ASIC mining!

17 thoughts on “Litecoin Mining on Mac OS X – DualMiner ASICs

    1. nwoolls Post author

      MultiMiner supports it but there is not an official version of BFGMiner that does. Since MultiMiner downloads the official version of BFGMiner, you will need to download one of the pre-compiled pre-releases of BFGMiner 4.0 (or compile it yourself). Then you can drop it in the MultiMiner\miners\bfgminer folder.

      1. wayann

        I thought that the dualminer drivers where compatible with gridseed
        bfgminer -d? -S noauto -S dualminer:all –scrypt doesn’t list any gridseed… am I missing something?
        in the meanwhile I switch back to your gridseed branch

  1. Josh

    Thank you very much for the tutorial! I’ve been trying to get my dualminer usb to work for days using macminer to no avail, this was quick and easy! I underclocked slightly to 800 averaging 65kh/s 100% valid so far. I’ll try overclocking when I have more time to be around the computer.

  2. Matthew

    Even after installing FTDI driver, GridSeed5 still shows up as a modem.

    [2014-03-31 10:29:02] lowlevel_scan: Found vcom device at dev_t:0d000012 (path=/dev/cu.usbmodemfa14141, vid=0000, pid=0000, manuf=(null), prod=(null), serial=(null))

    $ bfgminer –version
    bfgminer 3.99.0

    Can I still mine even though it shows incorrectly? Can I force bfgminer to communicate?

    1. Matthew

      I gave up on getting the Orbit to work on Mac OS X. Got it working on my raspberryPi, which is where it was going to end up anyways. I just wanted to test it out first on my Mac. This is the guide I used.

  3. Alexandre Vallières-Lagacé

    Hello and thank you for this!

    I have started to play around with two DualMiner USB (dual mode one and Scrypt-only one). It can run for many days without a hiccup!

    I was wondering if you had success with overclocking the DMUs? I tried it and it basically crashed my Mac… I have received a few heatsinks for the chips and I want to test and see if they get cooler with those in the end. Also have an Artic USB fan for the moment just in case :)

    Thanks for the great tools and articles!

    1. Blue Bear Systems

      I’ve overclocked the DualMiners using the –dualminer-pll 900 argument on a MacBook Pro Core 2 and not had any issues. I’m using a D-Link 7-port 5V/3A hub. The manufacturer has noted that not all chips will run at the 900 clock setting and I suspect the early manufacturing runs had this issue – one of my early units had to be RMAed because it just wouldn’t work. That being said, the gain in hash rate wasn’t huge and cgminer reported a few HW errors, which it typically does not when not OC’ed.

  4. Colton

    Thank you!!! You’re a life saver! You got my new DualMiner up and running on my Mac in no time. Nothing but smooth sailing from here

  5. Pingback: Litecoin mining | Bitcoin Mining Robots

  6. Alex

    Hi Nate,
    Thanks for the bfgminer support for Gridseed 5chip! It works better than cgminer port!

    Do you know how to dual mine (btc and ltc) using bfgminer for Gridseed 5chip?

  7. Pingback: Litecoin Mining on Mac OS X – GridSeed ASICs |

  8. James

    I’m getting the same ”
    dyld: Library not loaded: /usr/local/lib/libjansson.4.dylib
    Referenced from: /usr/local/bin/bfgminer
    Reason: Incompatible library version: bfgminer requires version 11.0.0 or later, but libjansson.4.dylib provides version 10.0.0
    Any help appreciated!

  9. Pingback: Litecoin Mining on Mac OS X – G-Black ASICs |

  10. Daniel Oates-Lee

    Has anyone found a fix for the “Reason: Incompatible library version: bfgminer requires version 11.0.0 or later, but libjansson.4.dylib provides version 10.0.0″?

  11. Daniel Oates-Lee

    I’ve found a fix for this …. Run the command “brew install libusb jansson”, if they are installed the symlinks are missing.
    Just run the following
    brew link –overwrite jansson
    brew link –overwrite libusb
    bfgminer should now execute :)


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