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Parallel port jtag

Distributed Feeds - July 11, 2014 - 2:45pm
I've been using a homebrew version of the Xilinx DLC5 parallel port jtag adapter for programming my fpga boards. The DLC5 is no longer supported by Xilinx, but some Linux jtag programmers still support it.
Recently I moved to a new PC, and my DLC5 hack no longer works with that parallel port. I can see on the scope that the right pins are moving, but the chip won't program. I suspect that either the rise and fall times are too slow, or there's noise on the signal lines.
Anyway, I had a sample of the SiLabs si8663 digital isolator, so I decided it's time to build a new interface. The Si8663 is a hex isolator (3 signals each direction), that's spec'ed to operate up to 150 Mbps bit rate (WAY more than needed for this app). Another neat feature is that the drivers on each side work from 2.5 to 5.5 volts, providing a level shifter at no extra charge.
Board is available on OshPark ( for anyone interested. Project name is "isopartag 140513". Circuit's simple: chip + 4 bypass caps on the bottom. The design includes resistors to tap power from unused pins of the parallel port, but they haven't been added yet, to that feature is untested. For now I just tap 5 volts from an unused keyboard or mouse port.
Caution:The Si8663 comes in two versions: a wide body for safety isolation, and a narrow body intended more for electrical noise isolation. I'm using the narrow version, and the board is not designed with wide separation between the input and output sides. In other words, this design is for low voltages only, don't use it where safety is an issue.
Categories: Planet FPGA

Intro to FPGA and CPLD: Lesson 3 Live!

Distributed Feeds - July 10, 2014 - 11:35am
This week we’re moving on to Lesson 3: Input & Output in our new PyroEDU course: An Introduction to CPLD and FPGA. Here’s an overview of the lesson:

"All FPGA and CPLD devices have general purpose input and output pins, often called GPIO. Here we will take a look at how to build a CPLD image and hardware to accept push-button input in order to affect output LEDs."

This online course is also be available through:
uReddit – P2PU
Categories: Planet FPGA

Cheaper FPGA boards are getting closer

Distributed Feeds - July 9, 2014 - 9:41am

Michael Dunn have done a research on FPGA boards available for less than $100. We all know that hobby market is always looking for low price hardware to do amazing projects. We already have almost free microcontroller boards including 8-bit and 32-bit ARM. FPGA always were was behind barrier. Not things seems to changing.


Today you can get quit several FPGA boards for your projects that are under $100 limit. You can find boards from Altera, Cypress, Lattice, Microsemi, Xilink and even more that aren’t listed. The lowest price you can find is like $4 for PSoC 4 FPGA board (at least more or less). In that price range you can get up to 22 kLE (logic elements). This is more than enough to run soft processor, build calculus intense projects like signal generators, scopes, signal processing modules and other projects where microcontrollers wouldn’t have enough juice. It takes some learning to get used to them, but there is quite enough tutorials to get started.

Categories: Planet FPGA

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