Author Topic: Total beginner at FPGA  (Read 10639 times)

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Offline hamster_nz

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Re: Total beginner at FPGA
« Reply #50 on: December 31, 2020, 09:07:58 pm »
It is like saying 'I want to take up cycling as a sport'.

You can pop down your local big-box store and buy a $100 bike and aseemble it. It will have two wheels and a handlebar just like any other bike. You will be able to ride down to the local store on it, on nice paved roads.

But if you really want to have a bike which will take you places, down tracks and trails you don't even know about yet, and will not break down and leave you stranded then move to a good known brand for a specialist retailer.

How many hours do you want to be stranded, figuring things out complex issues on your own, because of lack of documentation and as nobody (not even Google) can offer you meaningful advice?

A nice FPGA board is a pleasure to work with, and allows you to focus on your learning and experimenting, not trying to get the blasted thing just to accept a bit stream, clock properly, or work out that your LEDs are active low.

I recommend you find the resources you want to use to learn (PDFs, courses, YouTube subs) then get the board they use.

Gaze not into the abyss, lest you become recognized as an abyss domain expert, and they expect you keep gazing into the damn thing.
 

Offline james_s

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Re: Total beginner at FPGA
« Reply #51 on: January 10, 2021, 12:50:31 am »
Why laugh? For a beginner, it's good enough. $49.
It's fine for beginners, but calling it "powerful" is just wrong. Call it for what it really is - low end device good enough for very simple projects.

The smallest 10 year old FPGAs on the market are "powerful" relative to the small microcontrollers most hobbyists are used to working with. A single IC that I can fit an entire 8 bit computer with VGA video output inside it is "powerful" in my book. It may not be spectacular compared to the state of the art but even small FPGAs can be very capable.
 

Offline james_s

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Re: Total beginner at FPGA
« Reply #52 on: January 10, 2021, 12:52:24 am »
If design works with MEMS, there is exactly zero reasons to bother with changing oscillators.

But starter kit is not intended for a limited design. It should works good for different tasks, include frequency meter project and analog data acquisition and processing from high speed ADC/DAC ;)

If you want to make a frequency counter then connect an external high stability timebase, OCXO or GPSDO. I have never once found it necessary to replace the onboard oscillator on any of my FPGA boards, I just haven't built anything where it matters.
 

Offline james_s

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Re: Total beginner at FPGA
« Reply #53 on: January 10, 2021, 12:57:33 am »
And I would have to buy 10 starter kits to come anywhere close to an Artix 7 100T variant in terms of LUTs and BlockRAM (my two important characteristics).
Not really, Their (QMTech's) starter kit version with XC7A100T costs just $100.
But where is the 8 digit 7-segment display to hold the Accumulator and Program Counter displays?
How about the 16 switches for Console Entry Switches?
Or the 16 LEDs for status information?
Or even the push buttons for Run, Halt and Single Step?

I realize that not everybody needs those features and I also realize the Digilent board is expensive, but I do need the features and I don't care about the extra cost.  Rigging up something off the board is certainly possible.  I have used one of the Maxim display chips to create 16 7-segment digits over an SPI bus and it worked very well.  I also used a port expander to collect up 16 console entry switches over SPI.  I would prefer to have the gadgets on the board rather than laying on the bench.  Or worse, group mounted on a plywood backboard.  Actually, that worked out rather well.  Considering...

Another use for the console switches:  Implement breakpoints based on the PC.  This is sometimes useful when bringing up an OS.  Once the CPU has hit the breakpoint, resort to single stepping.  The status LEDs will be helpful!

Connect them externally if you need them. I have a handful of "drivers" in the form of HDL files I can instantiate into larger designs that drive various serially interfaced displays and input devices. A PS/2 keyboard and 8 (or however many) digit LED display can be connected with 4 or 5 pins and a handful of logic fabric.
 


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