Programmable Logic II – CPL

There is a wide assortment of cheap development (dev) boards for Complex Programmable Logic Devices (CPLD), the smaller cousin of the Field Programmable Logic Array (FPLA)

Using an inexpensive board and the development software that’s free to download from the major programmable companies such as Xilinx and Altera, the only additional thing needed is a programmer module. Cheap ones are available on Ebay but I am hoping that someone takes the time to teach an ARM/Arduino to step in as a programmer.

I have a small collection of dev boards including some Ebay specials and also designs I did a few years ago to choose from. For today I am grabbing a newer board that has not been fully checked out yet; an Altera Max V device. I have stuffed the CPLD, the clock oscillator, some LED’s and part of the onboard power supply along with the JTAG header needed to program the CPLD and that’s about it.


Herdware CPLD 5M570ZT

Herdware CPLD 5M570ZT dedicated PCB with SRAM.


CPLD Schematic

CPLD Schematic showing an Altera CPLD 5M570T144

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HDMI color processing board used as an FPGA dev board to mine Bitcoins


The blue board seen above is the guts of a product called the eeColor Color3. It was designed to act as a pass-through between your television and HDMI source device. It boasts the ability to adjust the color saturation to suit any viewing conditions. But [Taylor Killian] could care less about what the thing was made for, he tore it open and used the FPGA inside for his own purposes.

The obvious problem with this compared to a proper dev board is that the pins are not all broken out in a user-friendly way. But he got his hands on it for free after a mail-in-rebate (you might find one online for less than $10 if you’re lucky) and it’s got an Altera Cyclone IV chip with 30k (EP4CE30F23C6N) gates in it so he’s not complaining. The first project he took on with his new toy was to load up an open source Bitcoin mining program. The image above shows it grinding away at 15 megahashes per second while consuming only 2.5 watts. Not bad. Now he just needs to make a modular rack to hold a mining farm.

Dabbling with CPLD generated VGA signals

It seems like all the cool kids are leaving the 8-bit hobby microcontrollers in the parts bin and playing with more advanced parts like Complex Programmable Logic Devices. [Chris] is no exception to the trend, and set out to generate his own VGA signal using one of the beefy semiconductors.

It seems that he’s using the acronyms CPDL and FPGA interchangeable in his post but according to the parts list this setup uses an Altera EPM7128SLC84-7N CPLD. In order to generate the VGA signal he needed a way to convert the digital signals from the chip into the analog values called for in the video standard. He chose to build a Digital Analog Converter for the RGB color values using a resistor network which he calculated using PSpice. The other piece in the puzzle is a 25.175 MHz oscillator to clock the CPLD. As you can see after the break, his wire-wrapped prototype works exactly as designed. The example code generates the rainbow bars seen above, or a bouncing box demo reminiscent of a DVD player screen saver.

Want to know more about programming CPLDs? We did a tutorial on the subject a while back.

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Sequencer built on a Cycle II FPGA board

[Matt's] finishing up his computer science degree. As part of a class assignment he programmed his own sequencer which runs on a Cyclone-II FPGA development board. We’ve embedded a video below the fold that shows you what it can do. The buttons and LEDs offered on the board actually allowed him to create a nice user interface. Each slide switch has a surface mount LED above it, giving feedback for which beats in the loop are on and off. There’s also a bank of momentary-push buttons seen in blue above. [Matt] uses these to tweak settings like the pitch that is stored for each slide switch. He even puts on a light show with the VGA output.

We’ve seen this Altera board before, used to drive a falling sands game. The hardware will run you around $200 but that’s not bad considering all of the fun things you can do with it.

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Falling sand game on an FPGA

This falling sand game runs on a field-programmable gate array. The Altera Cyclone II resides at the heart of that development board, running the game which was written in Verilog. [Skyler Schneider] modeled his project after a Java version of the game called Pyro Sand Game. He treats each pixel of the 640×480 VGA screen as its own cell, following a set of rules to change the cells around it. This is very similar to Conway’s Game of Life, except that there are different categories of cells that behave uniquely (oil, water, plant, fire, etc.) and gravity is a key factor. Of particular interest to us were the rules for each cell, and the method [Skyler] used to feed and sync the VGA output. After the break you can see his demonstration videos, which walk through all of the features including the Troll button.

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Game Boy VGA using an FPGA

[ViDAR] was looking for a project to keep him occupied and settled on creating a VGA converter for his Game Boy. He had some difficulty finding pinouts for the LCD and CPU but working with what was known, and an oscilloscope, he found the necessary signal. Tap into just a few lines using those thin blue wires; Vsync, Hsync, clock, and two data pins. From there a development board with an Altera Cyclone II field-programmable gate array takes care of the heavy lifting. The board already has hardware for a VGA connection so it was just a matter of processing the incoming signals into the VGA standard. His demo video is embedded after the page break.

Want a dedicated solution? Check out this Game Boy video adapter inside a VHS cassette.

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Robot follows the rules of the road

This is a fantastic high school project. [Shmendrik213] built and robot a programmed it to follow common traffic rules. The robot drives itself with a DC motor, using one servo for steering and another to pan a webcam back and forth. The netbook that comes along for the ride is running a VB.NET program that can detect an upcoming intersection, read the street sign, and react based on other cars currently at the intersection.

The hardware is running on an Altera processor using firmware programmed in VHDL. We remember building a tissue box holder for one of our high school projects. Looks like the times have changed since then.