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Soft radio dev kits run Linux on ARM/FPGA SoCs

Oct 23, 2013 — by Eric Brown — 6,166 views
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Avnet released two Linux-based Software Defined Radio (SDR) development kits that combine Xilinx ARM/FPGA Zynq-7000 SoCs with Analog Devices RF transceiver modules. The SDR Evaluation Kit uses the community-backed Zedboard SBC and supports 2.4 to 2.5GHz operation, while the more advanced SDR Systems Development Kit is based on a Xilinx ZC706 baseboard and spans the spectrum from 70MHz to 6GHz.

Avnet’s new SDR development kits are built around two different Zynq-7000 based single board computers (SBCs), accompanied by slightly different versions of an Analog Devices Inc. (ADI) AD-FMCOMMSx-EBZ FMC radio module, featuring the new Analog Devices AD9361 RF Agile Transceiver for SDR.

AD9361 SDR Evaluation Kit and its ADI transceiver module
(click image to enlarge)


For its controlling SBC, the lower-cost ($1,495) AD9361 SDR Evaluation Kit (shown above) taps the community-backed Zedboard SBC, which normally costs $395. The $3,595 AD9361 “Software-Defined Radio Systems Development Kit,” meanwhile, is equipped with Xilinx’s own feature-rich $2,495 ZC706 reference board.

The Xilinx Zynq-7000 system-on-chip (SoC), which serves as the basis of both SDR kits, combines dual 667MHz Cortex-A9 cores and FPGA programmable logic. The SoC’s ARM subsystem is tightly linked via high-speed AXI interconnects and cross-point switches to an FPGA subsystem that offers the equivalent programmable logic of an Artix-7 FPGA. The FPGA provides 85,000 logic cells, 53,200 look-up tables (LUTs), and 276 GMACS of peak DSP performance.

The two SDR dev kits integrate slightly different flavors of the Analog Devices AD-FMCOMMSx-EBZ FMC module, featuring its new AD9361 RF Agile Transceiver for SDR. The Zedboard-based SDR Evaluation Kit provides the AD-FMCOMMS2-EBZ FMC, while the ZC706-based SDR Systems Development Kit includes a third generation AD-FMCOMMS3-EBZ FMC. The product page for the newer “3” model was not available at publication time, so the differences between two ADI FMC modules are not clear, beyond optimized frequency tuning. The AD-FMCOMMS2-EBZ model is optimized for 2.4GHz communications (2400-2500MHz), while the AD-FMCOMMS3-EBZ found in the ZC706-based Systems Development Kit, supports the wider 70MHz to 6.0GHz range provided by both modules’s AD9361 transceiver.

Both SDR dev kits also include four Pulse 4G LTE blade antennas, which attach to the FMC modules. In addition, they provide Xilinx Vivado software and Linux development software on an 8GB SD card. Avnet’s Zynq SDR kits are both targeted at SDR, MIMO, public safety networks and general purpose data acquisition applications, enabling wireless communications from baseband to RF, says the company.

Zedboard and Xilinx ZC706 SBC details

The $1,495 Zynq SDR Evaluation kit makes use of Avnet’s community backed, open spec Zedboard single board computer (SBC), shown below, which has already sold over 3,000 units, according to the company. While the $395 ZedBoard includes a Zynq-7020 SoC, Avnet’s ZedBoard community also offers a similarly Linux-ready, $199 MicroZed SBC with less extensive I/O and a cheaper Zynq-7010 SoC with less capable FPGA functionality.

Zedboard SBC
(click image to enlarge)


The ZedBoard ships with 512MB of DDR3 memory and 256MB of QSPI (Quad SPI) flash, as well as a full-sized SD/MMC card cage. Real-world ports include gigabit Ethernet, micro-USB OTG, and a second micro-USB port for JTAG debugging. There’s also an HDMI, VGA, and audio ports, as well as an onboard connector for a 128 x 32-pixel OLED status display.

ZedBoard expansion connectors expose I/O functions from both the ARM CPU and FPGA fabric subsystems of the Zynq-7020. Most of the FPGA-related functions are available via XADC headers and FLM (LPC) connectors. Several PMOD analog inputs are available as well. (For more on the ZedBoard, please see our earlier ZedBoard coverage.)

The $3,595 Zynq SDR Systems Development Kit moves up from the ZedBoard to the Xilinx ZC706 reference board (shown below), formally known as the Zynq-7000 All Programmable SoC ZC706 Evaluation Kit. Despite the board coming from Xilinx, Avnet’s ZC706-based kit will be supported by the ZedBoard community as well.

Xilinx ZC706 baseboard
(click image for larger view with callouts)


Compared to the ZedBoard, the ZC706 offers four times the RAM (1GB component DDR3 and 1GB SODIMM DDR3) and far more QSPI flash, up to 32MB. Other features not found on the ZedBoard include four PCI Express lanes, a CAN bus, a second LPC expansion bus, and HDMI in, as well as out, among other enhancements.

The ZC706 also ships with a full seat version of the Xilinx Vivado Design Suite: Design Edition, used for FPGA development. (More information may be found on the Xilinx ZC706 product page.)

Analog Devices AD-FMCOMMS2-EBZ FMC module

In addition to supporting SDR, the Analog Devices AD-FMCOMMSx-EBZ FMC modules are designed for use in a wide range of RF (radio frequency) applications like 3G and 4G base stations and test equipment applications. As noted, Analog Devices has yet to post information on its AD-FMCOMMS3-EBZ FMC module found in the pricier Zynq-7000 Systems Development Kit, but the product page should appear soon. For now we only have information on the AD-FMCOMMS2-EBZ FMC. Presumably, the only major difference is that this second-generation model found on the ZedBoard-based Evaluation Kit is optimized for 2400MHz to 2500MHz RF communications while the third-gen model offers the wider 70MHz to 6.0GHz frequency range.

The 2.4GHz-focused AD-FMCOMMS2-EBZ FMC module combines an RF front end with mixed-signal baseband section and integrated frequency synthesizers. Offered in a 2 x 2 RF configuration, the module is fully customizable by software without any hardware changes, providing options for GPS or IEEE 1588 Synchronization, and MIMO configurations, says ADI.

Additional AD-FMCOMMS2-EBZ FMC features are said to include:

  • Channel bandwidth of < 200KHz to 56MHz
  • RF section bypass for baseband sampling
  • Phase and frequency synchronization on both transmit and receive paths
  • Allows high channel density
  • Powered from single FMC connector
  • Supports MIMO radio, with less than 1 sample sync on both ADC and DAC
  • Includes schematics, layout, BOM, HDL, Linux drivers, and application software
  • Supports add-on cards for spectrum specific designs (PA, LNA, etc.)

At the heart of both Analog Devices FMC module versions is an AD9361 RF agile transceiver. The radio integrates 12-bit DACs and ADCs, with dual receivers featuring either 6x differential or 12x single-ended inputs. The part offers < 2.5 dB noise sensitivity and RX gain control, among other enhancements, says ADI.

Further information

Avnet’s “Zynq-7000 All Programmable SoC / AD9361 Software-Defined Radio Evaluation Kit” ($1,495) and “Zynq-7000 All Programmable SoC / AD9361 Software-Defined Radio Systems Development Kit” ($3,595) are available for order now, and will begin shipping in November. More information may be found at the Zynq 7000 SDR Evaluation Kit and Zynq 7000 SDR Systems Development Kit product pages, respectively.

More details on Xilinx’s SDR solutions may be found here.

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