There is a wide range of development boards on the market today. Some are ideal for beginners who are just learning programmable logic or SoC design and others are more targeted for increasing technology readiness level (TRL) in professional applications where the development board is used to implement the application (or key elements of the it) prior to custom electronics being made available.
One of the key things on those development boards that can be used to increase the TRL of the application is interfacing. When it comes to FPGA development boards, these interfaces are typically split into the following:
PMOD – Low-speed interface ideal for GPIO, SPI, I2C etc. tied to 3v3 operation.
SYZYGY – Compact high-speed interface supporting both transceivers and a range of IO voltages and standards.
FMC – High-speed Interface supporting both transceivers and a range of IO voltages and standards.
High-speed interfaces use both transceivers and differential standards such as LVDS used by high-performance ADC and DACS.
One board I recently received which provides good interfacing capabilities is the Digilent Eclypse Z7. This board provides the developer with a Zynq-7020 coupled with 1 GB of DDR3 memory and 16 MB of SPI flash. When it comes to interfacing, the board provides standard interfaces common to many development boards including Gigabit Ethernet, USB OTG and USB-UART / JTAG.
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The most exciting part about the board is the two SYZYGY interfaces. Each of these ports provides a dedicated clocking input and output, eight differential signals (or 16 single ended), and 12 additional single ended signals. SYZYGY also offers programmable VIO to support a wide range of interfaces.
There are several interface cards which can be added to the Eclypse Z7 and SYZYGY ports. The following three different SYZYGY cards (called ZMods by Digilient) are offered by Digilent.
Zmod Scope – 14-bit resolution 105 mega sample per second ADC
Zmod Digitizer – 14-bit resolution 125 mega sample per second ADC
Zmod AWG – 14-bit resolution 100 mega sample per second DAC
Interestingly, these Zmods can be used on the Eclypse Z7 in combination with Digilent’s WaveForms software. This gives you the ability to connect using the WaveForms software from your development machine to the actual ADC and DAC used in the system. Data can be gathered very quickly from the real-world ADC and DACs to enable the algorithms to be run on the real data with real-world sensors. For many applications this can be very significant.
To get started testing with WaveForms on the Digilent Eclypse Z7, we first need to install the WaveForms software. With the WaveForms software download we also get the FPGA programming image which can be used for the Eclypse Z7. I used DCFG_07_01_01 which I renamed to boot.bin on the SD card. This build has either the scope or digitiser on Zmod A while the digitiser is on Zmod B.
With the Zmods installed, the SD card inserted, and the boot mode set to SD, open WaveForms software to show the Eclypse Z7.
We can then use the Waveforms program to drive the AWG and the scope to sample the input signals.
For this example, I just looped back the outputs to the inputs and captured the waveforms.
I like this board because it fits a nice point in the market and supports two SZYGZY interfaces. If you want to know a little more about how to create digital filters with it, I created an in depth tutorial here.
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