USRP Hardware Driver and USRP Manual  Version: 003.009.004-0-g2b5a88bb
UHD and USRP Manual
Configuring Devices and Streamers

Device Configuration through address string

The address string for a device is mainly used to identify a device (see also Device Identification), but it can also be used to propagate settings to the device.

As an example, say you run rx_samples_to_file with the following settings:

$ rx_samples_to_file --args type=b200,master_clock_rate=16e6

This will first use the type flag to search your system for connected B200 or B210 devices, as described on Device Identification. Once it has found one of these, it will connect to it and pass the master_clock_rate=16e6 option to the device initialization (in this case, it will set the master clock rate to 16 MHz as described on Changing the Master Clock Rate).

The following table lists the configuration options you can pass as device arguments. Also check out the individual device manuals for more information and possible more options.

Key Description Supported Devices Example Value
blank_eeprom Caution! Having this key will erase the EEPROM and can damage your device! X3x0 blank_eeprom=1
fpga Provide alternative FPGA bitfile All USB Devices, X3x0 (PCIe only), All embedded devices fpga=/path/to/bitfile.bit
fw Provide alternative firmware All USB Devices, X3x0 fw=/path/to/fw.bin
ignore-cal-file Ignores existing device calibration files All Devices with cal-file supportSee Ignoring Calibration Files
master_clock_rate Master Clock Rate in Hz X3x0, B2x0, B1x0, E3x0, E1x0 master_clock_rate=16e6
mcr Override master clock rate settings (see External clock modification) USRP1 mcr=52e6
niusrprpc_port RPC Port for NI USRP RIO X3x0 niusrprpc_port=5445
system_ref_rate Reference Clock Rate in Hz X3x0 system_ref_rate=10e6

In addition, many of the streaming-related options can be set per-device at configuration time. See Streaming Arguments (Stream Args) and Transport Notes for more details.

Specifying the Subdevice

A subdevice specification (or "subdev spec") string for USRP family devices is composed of:

<motherboard slot name>:<daughterboard frontend name>

Ex: The subdev spec markup string to select a WBX on slot B.


Ex: The subdev spec markup string to select a BasicRX on slot B.


-- OR --


-- OR --


A subdev spec can consist of multiple strings if a motherboard has the option for more than one radio device. In the X300, you may have an SBX in slot A and a CBX in slot B. Both of these daughterboards have one frontend ("0"), so the subdev spec to configure both these radio channels would look like this:

A:0 B:0

The individual subdev specs are separated by spaces. On some devices, such as the X300 or the B200, it is possible to swap these to hint that slot B should be the first radio ("channel 0") and slot A should be the second radio ("channel 1"):

B:0 A:0

On devices with more than one radio, setting the subdev spec to a single value declares that the other radio is not used. In a configuration with multiple USRPs, this means that this device will only be assigned a single channel.

Note that a subdev spec string always only pertains to a single USRP, even if multiple USRPs are configured to run together. For such a configuration, you set a subdev spec string for every device individually.

USRP Family Motherboard Slot Names

All USRP family motherboards have a first slot named A:. The USRP1 and X3x0 have two daughterboard subdevice slots, known as A: and B:.

The B210 and E310 series have a different configuration, since their two radios are logically connected to the same "daughterboard" (which is in reality the integrated AD9361), but different frontends. To select both radios on a B200 or an E300, use this string:


USRP Family Motherboard Slot Names

Daughterboard Frontend Names

Daughterboard frontend names can be used to specify which signal path is used from a daughterboard. Most daughterboards have only one frontend :0. A few daughterboards (Basic, LF and TVRX2) have multiple frontend names available. The frontend names are documented in Daughterboards.

Streaming Arguments (Stream Args)

When initializing a streamer using uhd::device::get_tx_stream() and/or uhd::device::get_rx_stream(), you must specify a uhd::stream_args_t object (see the manual for this struct and an in-depth explanation of the individual components).