Kit Introduces Designers to CPLDs

When a circuit needs logic components, but too many for discretechips and not enough to justify a field-programmable gate array, a complexprogrammable logic device (CPLD) could do the job. Altera's new MAX V kitprovides a CPLD with as many as 570 logic elements, 8 Kbytes of flash memory,and 159 user I/O lines. Those I/O lines connect to two 40-pin male headers aswell as two connectors for small dc motors (not supplied). It has a USBconnection with a host PC supplies power, although you can connect the board toan external power supply.

Engineers and designers who need to investigate or use CPLDs andwho can start without a stepwise tutorial might like this kit. It took longerthan expected to use an online tutorial and switch back and forth to the AlteraQuartus II design software. The online tutorial uses an FPGA as an example, soit's not a perfect fit for CPLD designs, but it comes close. I had expectedmore tutorial information created specifically to demonstrate creation of acircuit that would run on the MAX V board.

The kit took only a few minutes to set up and connect to my labPC. Instead of following the brief Quick Start Guide I recommend peopledownload and print the "MAX V CPLDDevelopment Kit User Guide," which provides information about the board,how to check its configuration, and how to run several demonstration programs.This 29-page document includes many hot links, but print it and the linksvanish and you get no list of URLs. I had to keep the guide open on my PC toeasily get to other reference materials. Perhaps a new version of the guidewill include URLs for these embedded links. A hot link in the guide points to a Development Kit installer, forexample, that downloads examples, test software, documents, PCB layouts, andinformation needed to use the kit.

A second document, "MAX V Development Board ReferenceManual," includes hardware and connector-pin information. I also neededinformation about how to install drivers for the USB-Blaster, basically a USBconnection with my lab PC that let me download a design to the CPLD. Anon-board JTAG controller handles the CPLD configuration and programming.

The User Guide explained how to set up Altera's Board Test Systemthat let me test the two LEDs and pushbuttons, monitor power use, test anexternal 10-MHz clock module and so on. The oscillator drops into a socket, sousers can select an oscillator with a different frequency or use an off-boardclock signal. I had no problems with the hardware. But after running the tests you'repretty much on your own. Altera has no tutorial that goes through a simplestep-by-step design specifically for this board. So I put together my own.

To create a logic design and test it in the CPLD you use Altera'sQuartus II software (ver 10.1), so I went to the company's site and downloadedthe 3-Gbyte free Quartus II Web Edition and installed it. I had not usedQuartus, so I signed up for a free "anytime" video course that guidedme through the steps to create a project, add circuit elements, compile adesign, assign pins, and load the design into an FPGA. The tutorial didn'tmention CPLDs and any programming differences between them and FPGAs. It becamea chore, though, to go back and forth between the video course and the Quartusscreen. In addition, the Quartus Web Edition crashed three times and each crashmeant a fresh restart with Quartus and the training. At this point I wishedAltera had provided the coursework in printed form.

Eventually I happened upon the 136-page document,"Introduction to the Quartus II Software," but information aboutonline training never mentioned it. Here's the link:http://www.altera.com/literature/manual/intro_to_quartus2.pdf. The manualdoesn't take the place of the online training, though.

After the last crash I downloaded and installed the free 30-daytrial Subscription version of Quartus, thinking it might work better, which itdid. Beware, though. This 30-day trial Subscription software will not programdevices. That's not obvious from the start.

As a final attempt to create a design I set up two computers,downloaded the free Quartus II Web edition--again--overnight and installed it.(Altera offers software tools on a DVD, too.) I logged into the tutorial on thesecond computer and designed my simple circuit. By now I could perform several stepsat a time without having to stop the video, rewind, and start again. My projectcircuit compiled, loaded into the CPLD and worked. After creating the same circuit three of fourtimes I got into the routine of using Quartus. Total time for this project cameto two days, mainly because of software problems, some attributed to my errors,along with the need to watch video-training modules several times. bet awritten tutorial would take less time to complete. For example, see the helpfultutorial "NM201; MAX44 - Altera FPGA/CPLD Development Kit Board," at:http://www.northmicro.com/support/NM201TutorialQuartus.pdf.

Instead of using the 8-bit multiplier-and-memory example in thetraining, which aims at FPGA users, I followed the same tutorial steps butcreated a 2-bit comparator and inserted a NAND gate in the circuit. The circuitused the two pushbuttons as inputs and the two LEDs as outputs.

Suggested kit improvements: