Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [programmable-logic]

Programmable digital logic devices include FPGAs, CPLDs, and older devices such as GALs and PALs. Programmable logic enables flexibly implementing complex digital functions in a single chip, from a few gates of glue logic to entire microprocessors or complex signal processing systems.

Typically FPGAs and CPLDs are programmed using VHDL or Verilog.

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Are there any Analog FPGAs?

As I understand it FPGAs are flexible "digital" circuits, that let you design and build and rebuild a digital circuit. It might sound naive or silly but I was wondering if there are FPGAs or other "flexible" technologies that also make analog…
Ali
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Use cases for RAM-less microcontrollers

In a different question around a specific microcontroller (ATtiny12 - datasheet) I came to ask myself: What are the intended use cases for such devices? Does it target the segment: Too "complex" for a small PLD/CPLD and too "simple" for a…
ElectronicsStudent
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What would make me choose Verilog or VHDL over schematic design on CPLDs or FPGAs?

I have absolutely no background in programmable logic, I use mostly microcontrollers in my projects but recently I needed to work with video and the microcontroller is just too slow for what I needed so I started playing with CPLDs. I was able to…
Bruno Ferreira
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Accurate quadrature decoding without external clocking

An Incremental Encoder is a linear or rotary electromechanical device that has two output signals, A and B, which issue pulses when the device is moved. Together, the A and B signals indicate both the occurrence of and direction of movement. Below…
Pavel Stepanek
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Is there an inexpensive way to get started with GAL (Generic Array Logic) chips?

GAL chips seem expensive to get started with, since programmers cost hundreds of dollars and even ISP cables aren't cheap. Is there a cheaper way?
samoz
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What are programmable logic ICs of different complexity used for?

Programmable logic can be implemented in your widget in many different spectrums, from burning a few gates or using a MUX to the latest FPGA with built-in microcontroller and IO peripherals, not to mention ARM's PrimeCell GPIO or other, more…
tyblu
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Discrete logic design

I have been tasked with building a simple alarm device. It just needs to measure a few inputs and the outputs will respond accordingly (to put it very simply!). To me, it seemed that using a few discrete logic gates would get the job done, but a…
Curious
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What happens when an FPGA is powered on and left unconfigured?

I am trying to get a general understanding on what happens if you leave an FPGA unprogrammed for a long duration of time. Suppose you have an FPGA and you leave it unprogrammed for a long period of time (several minutes to hours after power-on),…
boffin
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MITM on I2C Bus

I've been trying to design a module that will allow me to modify selected slave responses on an I2C bus. Here is the original bus configuration (the pull-ups and power connections are not shown for clarity: There's only 2 devices on this bus and…
Alexxx
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What's the difference between CPLD and an FPGA?

What's the difference between a CPLD and an FPGA?
Sanjeev Kumar
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What are my less expensive options for getting started with CPLDs

I would like to goof around with some CPLD stuff and I see I have a couple options out there. I don't have a particular application in mind; it just seems like there a lot of possibilities, some of which are easier to use than others. The main…
mmccoo
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Should I use a resistor between an input pin of MCU/CPLD and VCC/GND?

Some times, I want my MCU or CPLD to input a static logic. So, I choose to tie it to VCC or GND. The problem is that should I put a resistor in series to limit the current? I just think by myself for a while and get my own answer: no! Take…
oilpig
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What is the difference between PLA and ROM?

I'm finding it hard to understand. What is the difference between PLA and ROM? Can somebody please provide a link or explanation?
hello
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Why does this Verilog hog down 30 macrocells and hundreds of product terms?

I have a project that's consuming 34 of a Xilinx Coolrunner II's macrocells. I noticed I had an error and tracked it down to this: assign rlever = RL[0] ? 3'b000 : RL[1] ? 3'b001 : RL[2] ? 3'b010 : …
Tony Ennis
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Counter for 20 GHz clock

I am designing time critical application where I need time resolution in order of 100 picoseconds. I am considering to make an ring oscillator of 20 GHz and clock from ring oscillator. Is there IC's for it or can I implement it using CoolRunner II…
Steve
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