This month’s article introduced you to the hard-core processor device known as Zynq. In particular I’m using the ZedBoard device, although there are now a few other boards available which I’ll mention. The article covered:
- What is Zynq
- Development Environment
- Peripheral Types
- Internal Buses
As usual the full article is in Circuit Cellar magazine, this page just includes the additional information I couldn’t fit in the article! If you have a digital subscription access it online at www.gotomycc.com otherwise see www.circuitcellar.com.
DISCLAIMER: I’m presenting information about features in the boards based on a reading published specifications. I may have made an error, or the device specifications may have changed since I made this page. Please confirm all specifications with vendor, as I am not making any sort of claims about these boards.
A word before I start comparing boards: the first two boards (ZedBoard & MicroZed) come with a device-locked version of Vivado Design Edition. This adds the ‘Integrated Logic Analyzer’ functionality into your debug environment when using Vivado (but does not add ChipScope). This is fairly valuable, as if you were to buy Vivado Design Edition it is around $2995 (but works with any device, not just the one mounted on the board). However when comparing boards be aware that some of the cost difference accounts for the better toolchain the boards come with.
The first ‘main’ board kicking off the whole Zynq interest was the ZedBoard ($319 academic), which has an online community at www.zedboard.org. This board has built in USB-JTAG & also a normal JTAG connector. The board looks like this:
More recently the MicroZed was introduced, which is available at a lower cost ($199). The main disadvantage of the MicroZed is there is only a single 0.1×0.1″ header which you can easily interface to. This header is only connected to the ‘Processing System’ (PS) on the Zynq device, meaning you cannot make a connection between the FPGA (PL portion) of the Zynq and a physical device without an add-on card, the IO Carrier board. For the cost of an IO Carrier + a MicroZed you could buy a ZedBoard, so there’s no cost advantage there. Note the IO carrier *does* break out a lot more IO, so if you envision yourself using boatloads of medium-speed IO it’s a reasonable thing to have. This board has built in USB-JTAG & also a normal JTAG connector. The MicroZed looks like this:
Digilent Inc recently introduced the Zybo device, which looks like a pretty nice development environment, especially given the low cost ($125 academic). The one downside is it DOES NOT have any high-speed IO connector. The ZedBoard can be used as a high-speed ADC development plaform and all sorts of other stuff, whereas the Zybo cannot be used for this since it’s limited to medium-speed 0.1×0.1″ headers. This board has built in USB-JTAG & also a normal JTAG connector.
Another very cool board which might be available when you read this is the Red Pitaya. It was actually sold as the amazing open-source instrument, but basically contains a Zynq + 2 channel ADC + 2 channel DAC. The connections of the ADC & ZYNQ device are publicly posted in a GIT repository, so you could just use it as a regular development board. Considering the cost ($449) it’s cheaper than buying a FPGA board + buying a high-speed ADC/DAC add-on card. It also brings a few differential pairs out to SATA style connectors. They ARE NOT gigibit transceivers driving them, but if you wanted to experiment with ‘fast IO’ without investing in a complete FMC card it’s a good mid-range option. There’s no built-in USB JTAG or anything like that, so you can’t run ChipScope or similar. If you have a supported USB-JTAG cable you can connect to the provided JTAG headers, and you may need a JTAG adapter to program the Zynq device anyway.
It would be hard to mention the Red Pitaya without also mentioning the Parallela. This is less of a generic board, but it’s interesting use of the Zynq processor. It’s also the cheapest at $99, but you get zero 0.1×0.1″ connectors (it’s all SMD on the backside). There’s no built-in JTAG or anything like that, so you can’t run ChipScope or similar. I don’t even know if there is an easy way to access just the Zynq SoC for downloading bitstreams etc, but it’s still a cool board I wanted to point out.
Example Project – FFT
One of the examples I mention is a comparison of how a FFT can be implemented in software or hardware. This example pulls on David Lautzenheiser of Faster Technology’s great example in the Xilinx Wiki.
You can see the following two links for the software and hardware respectively:
Example Project – Using HLS
In the Feb 2014 issue of Circuit Cellar I already was using the Zynq device. So if you want, be sure to check out the February 2014 posting for a video of how to implement a project on the Zynq using HLS (hint: it’s very easy!). Here’s the video, as mentioned there is more details in the Feb 2014 CC Issue + PLIP Blog post.
One of the great things about the ZedBoard/MicroZed compared to other options, is the online community at ZedBoard.org .
Not only is there a number of reference designs, but also a fairly active community forum. Nothing is more frustrating than working on a problem & having little support. And if you’re working for a small engineering company, or as a hobbyist or student, you may just not be able to even get much in the way of official support! But since the ZedBoard is designed for use by a wide variety of such markets, the active forum gives you a much greater chance of success!