UHD - USRP-B1XX Series Application Notes

Table of Contents

Specify a non-standard image

The UHD will automatically select the USRP B-Series images from the installed images package. The image selection can be overridden with the "fpga" and "fw" device address parameters.

Example device address string representations to specify non-standard images:

fpga=usrp_b100_fpga_firmware.bin

-- OR --

fw=usrp_b100_fw_firmware.ihx

Changing the master clock rate

The master clock rate of the USRP embedded feeds both the FPGA DSP and the codec chip. Hundreds of rates between 32MHz and 64MHz are available. A few notable rates are:

Set 61.44MHz - uses external VCXO

To use the 61.44MHz clock rate, the USRP embedded will require two jumpers to be moved.

  • J16 is a two pin header, remove the jumper (or leave it on pin1 only)
  • J15 is a three pin header, move the jumper to (pin1, pin2)

Note: See instructions below to communicate the desired clock rate into the UHD.

Set other rates - uses internal VCO

To use other clock rates, the jumpers will need to be in the default position.

  • J16 is a two pin header, move the jumper to (pin1, pin2)
  • J15 is a three pin header, move the jumper to (pin2, pin3)

To communicate the desired clock rate into the UHD, specify the a special device address argument, where the key is "master_clock_rate" and the value is a rate in Hz. Example:

uhd_usrp_probe --args="master_clock_rate=52e6"

Hardware setup notes

Front panel LEDs

The LEDs on the front panel can be useful in debugging hardware and software issues. The LEDs reveal the following about the state of the device:

  • LED A: transmitting
  • LED B: fpga loaded
  • LED C: receiving
  • LED D: fpga loaded
  • LED E: reference lock
  • LED F: board power