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peepo
Posts: 306
Joined: Sun Oct 21, 2012 9:36 am

HDL? FPGA? why LOGiPi @ kickstarter?

Fri Jan 10, 2014 9:14 am

why HDL?
seems a hard nut to crack?
anyone seen a good simple introduction?

why is LOGi FPGA such a huge success at kickstarter?
http://www.kickstarter.com/projects/157 ... y-pi-beagl

sales pitch seems very techy, and the 2 Magpi articles have links but are also heavy going.

FPGA thread:
http://www.raspberrypi.org/phpBB3/viewt ... =63&t=2316

guzunty
Posts: 276
Joined: Mon Jan 14, 2013 10:13 am

Re: HDL? FPGA? why LOGiPi @ kickstarter?

Fri Jan 10, 2014 10:22 am

why HDL?
Because it is a way to implement things that run _way_ faster than the Pi processor can do it.
seems a hard nut to crack?
Not sure what you mean, HDL is hard to learn? It can be if you come from a traditional, imperative programming background because it is not always executed sequentially.
anyone seen a good simple introduction?
For a lower cost introduction, try the Guzunty design.

https://github.com/Guzunty/Pi/wiki

It is cheaper because you build it yourself. It is more robust because if you make a mistake and damage the main chip it can be easily and cheaply replaced.

As an introduction, Guzunty has many ready built cores to do different frequently needed jobs all ready to download, so you can play with it now and learn to use HDL later. The website includes instructions on how to download and set up the programming toolchain.

The Guzunty has far fewer gates than LogiPi, but its still capable of great things. Also note that it is based on a CPLD rather than an FPGA. It lacks RAM and so isn't great for anything that has to cache a lot of runtime state. It is fully programmable using HDL though. At the price, you can see if you like it/find it useful and buy an FPGA board later.

Choice is good.

For a perhaps less techie explanation, try the article on the Guzunty in MagPi issue 13.
Guzunty: A fully programmable peripheral you build yourself! https://github.com/Guzunty/Pi/wiki

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meltwater
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Re: HDL? FPGA? why LOGiPi @ kickstarter?

Fri Jan 10, 2014 11:52 am

I would agree that for beginners this is a excellent taster to get started with.

I think the added bonus is once you are ready to move onto more advanced stuff you can repurpose it into a PWM controller (I think this would drive servos) or an IO expander. For the price, it is great value learning.
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peepo
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Re: HDL? FPGA? why LOGiPi @ kickstarter?

Fri Jan 10, 2014 12:24 pm

I'm interested in the LogiPi with LogiCam,
the camera board & sensor appear similar to raspicam,
but the demo quality seems poor?

is there something similar for the GPU?
no idea what it might be called...

why is LOGiPi FPGA such a huge success at kickstarter?
or perhaps 800+ is not so many?

tx for techie comments and guzunty intro MagPi issue 14,

guzunty
Posts: 276
Joined: Mon Jan 14, 2013 10:13 am

Re: HDL? FPGA? why LOGiPi @ kickstarter?

Fri Jan 10, 2014 12:56 pm

> perhaps 800+ is not so many?
800 is not bad, but that is spread across RPi and BeagleBone Black, I estimate nearer 450 backers were Pi owners.

This is from a total potential market of 2 million Pi's shipped, so 0.0225%? It's ok for a product like this.

I think $69 for a Spartan 6 is a great deal, I think they are planning to ship regular orders at $99 which is still ok but quite a lot compared to the basic cost of a Pi, IMHO. By contrast, you can build a Guzunty for under $20, if you want to try out HDL. While the CPLD in the Guzunty can't provide much heavy lifting for a machine vision project, it can be useful in other ways as Meltwater mentioned.

> is there something similar for the GPU?
Similar to what? The machine vision filters? Probably not, the code in the Pi GPU is closed source. :-(

If the GPU were open source, I daresay those filters might be possible. The GPU source is closed because there are MPEG and other licensed codecs in there. Maybe the RPi Foundation could split the source and allow us to bind with a binary blob that contains the licensed code?

That would be cool. How about it RPiF?
Guzunty: A fully programmable peripheral you build yourself! https://github.com/Guzunty/Pi/wiki

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