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CGMiner 4.3.5 with GridSeed and Zeus scrypt ASIC support.

This file describes Scrypt-specific settings and options. For general CGMiner information refer to README. Scrypt algorithm code was ported from CGMiner version 3.7.2.


./configure --enable-scrypt --enable-zeus

Option Summary

  --zeus-chips <chips>   Default number of chips per device
  --zeus-clock <clock>   Default chip clock speed (MHz)

  --zeus-options <ID>,<chips>,<clock>[;<ID>,<chips>,<clock>...]
                         Set chips and clock speed for individual devices

  --zeus-nocheck-golden  Skip golden nonce verification during initialization (serial mode only)
  --zeus-debug           Enable extra Zeus driver debugging output in verbose mode

The zeus-chips and zeus-clock options apply to every device unless overridden on a per-device basis using zeus-options. The ID values to use with that option depend on how CGMiner is communicating with the miners, explained in the next section.

Device Selection

The driver supports using either libusb or directly reading/writing to the serial port to communicate with the miner. Libusb is generally more convenient on Linux while Windows users may prefer serial to bypass the requirement of installing special libusb drivers. Mode selection depends on the scan-serial option:

  • By default with no --scan-serial options the driver will use libusb to autodetect any connected miners and to perform all device I/O operations. In this mode the ID assigned to each miner for use with --zeus-options will be the miner's serial number (except for Blizzard models, see note below).

  • For serial I/O each miner must be specified manually using --scan-serial zeus:<PORT> and providing the path to the serial port (i.e. /dev/ttyUSBx on Linux or \\.\COMx on Windows). The prefix "zeus:" is optional if CGMiner has been compiled with only the Zeus driver enabled, otherwise it is required. In this mode the ID assigned to each miner for use with --zeus-options will be the final part of the port (i.e. ttyUSBx or COMx). Note that autodetection is not supported in this mode.

  • On Linux systems only it is possible to use serial I/O and still have autodetection by specifying --scan-serial zeus:auto. In this mode the driver will use libudev to identify which USB-serial ports are from a Zeus miner. All I/O will still be done using direct serial reads and writes (not through libusb) and the ID for each miner will still be the final part of the port (ttyUSBx). This method is not recommended if multiple drivers are compiled in as autodetection can be quirky in those cases.

The following three examples are equivalent assuming three miners are connected:

# Using libusb
./cgminer --scrypt --zeus-chips 96 --zeus-clock 328

# Direct serial I/O, manual port specification
./cgminer --scrypt --zeus-chips 96 --zeus-clock 328 --scan-serial /dev/ttyUSB0 \
	--scan-serial /dev/ttyUSB1 --scan-serial /dev/ttyUSB2

# Direct serial I/O, auto-detect ports (Linux only)
./cgminer --scrypt --zeus-chips 96 --zeus-clock 328 --scan-serial zeus:auto


Blizzard ID note: Blizzard models use a different USB-Serial chip which does not provide a valid serial number. When using libusb mode with one of these the ID shown in CGMiner and used with --zeus-options is the USB bus and device address in this format: <bus number>:<device address>

Chip count for different models: Blizzard: 6, Hurricane X2: 48, Hurricane X3: 64, Thunder X2: 96, Thunder X3: 128

The model name displayed in the CGMiner UI depends on the chip count being specified correctly. It is not auto-determined.

Zeus driver is based on documentation and the official reference implementation. Many thanks also to sling00 and LinuxETC for providing access to test hardware.


./configure --enable-scrypt --enable-gridseed

GC3355-specific options can be specified via --gridseed-options or "gridseed-options" in the configuration file as a comma-separated list of sub-options:

  • baud - miner baud rate (default 115200)
  • freq - any frequency multiple of 12.5 MHz, non-integer frequencies rounded up (default 600)
  • pll_r, pll_f, pll_od - fine-grained frequency tuning; see below
  • chips - number of chips per device (default 5)
  • per_chip_stats - print per-chip nonce generations and hardware failures (only for 5-chip models)
  • start_port - first port number for scrypt proxy mode (default 3350); see below
  • voltage - switch the voltage to the GC3355 chips; see below
  • led_off - turn off the LEDs on the Gridseed miner

When mining scrypt-only this version of cgminer does not initialize the SHA cores so that power usage is low. On a 5-chip USB miner, power usage is around 10 W.

Gridseed support is based largely on the original Gridseed CGMiner and dtbartle's scrypt modifications.

Frequency Tuning

If pll_r/pll_f/pll_od are specified, freq is ignored, and calculated as follows:

  • Fin = 25
  • Fref = int(Fin / (pll_r + 1))
  • Fvco = int(Fref * (pll_f + 1))
  • Fout = int(Fvco / (1 << pll_od))
  • freq = Fout

Dual Mining

When dual-mining start_port will set the listening proxy port of the first gridseed device on the SHA256 instance of cgminer, with additional miners using successive ports. The scrypt instance of cgminer will attempt to connect starting at this port.

When dual mining, start the SHA mining instance of cgminer first, wait for it to begin mining and then start the scrypt version. The second instance will detect that the USB ports are in use and will attempt to connect to the first via UDP.

If everything is working the same devices will appear in both cgminer windows.

Voltage Modding

If voltage=1 is set the gridseed chips will be switched to an alternate voltage. Specifically, this flag will cause the MCU to assert the VID0 input to the voltage regulator. This requires a voltmodded miner. On a stock unit this will actually reduce the regulator's output voltage.

More Complex Options

The options can also be specified for each device individually by serial number via --gridseed-freq or --gridseed-override or their configuration file equivalents. --gridseed-freq takes a comma-separated list of serial number to frequency mappings while --gridseed-override takes the same format as --gridseed-options:

--gridseed-freq "<SERIAL>=<FREQ>[,...]"

--gridseed-override "<SERIAL>:freq=<FREQ>,voltage=<0/1>[,...];<SERIAL>:freq=<FREQ>[,...[;...]]"


CGMiner 4.3.5 with Scrypt and support for Gridseed and Zeus ASICs




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