How to learn the FPGA from a scratch?

[ojer25]

First step to FPGA

DEAR Friends
Yes it's same asking
I'm beginner in FPGA field
so, i need a best way to learn it from scratch
and a cheap programmer kit to do this mission
Thanks
ojer25@hotmail.com
[/b][/quote]

 

[mhamed]

First step to FPGA

why you dont try Xilinx.com and its documentations?

 

[Big Boy]

Re: First step to FPGA

Going through doccumentations may not be the best approach if you don't know the basic structures of an FPGA.

To begin, it depend on if you have previous knowledge of any programmable logic, like simple PLD (PAL, GAL, ...). This is not required, but will at least give you an idea of how PLD, CPLD, and FPGA work. At a minimum, you need to have knowledge of logic gates (and/or/xor/...), and flip-flops. I mean, how they work...

Basically, an FPGA is composed of only a few relatively simple modules. Those modules are then interconnected togetter to form a more complex function.

One of the module is a logic cell. A logic cell is contain a LUT (look-up table) and a register (a single flip-flop). It also contains some gates, so that multiple LUT output can be combined together.

A LUT, a look-up table, is the equivalent of a PLD logic array. However, in a PLD, where you define connections between OR and AND gates, a LUT is simply a ROM-like structure (at runtime). It usually have 4 inputs, and give one output depending on the inputs. So, you could encode something like (A AND B) OR (/C AND D). The LUT is a simple table that for every A, B, C and D inputs, it output the corresponding output.

The flip-flop can be used as a single register element, controled by a CLK signal. It also have set and reset signals (synchronous and asynchronous).

The logic cell also have some specialized lines, like 'carry' lines. So, multiple cells can be joint together to create shift-register or added.

An FPGA usually contain hundreds to thousands of logic cells. Each of those cells are connected together via multiple lines. When you create a design, the program automatically connect some of those lines together to form a path between the different logic cells, depending on your design.

Another part of the FPGA is the IO Block. Each pins on your FPGA have one IOB. The IOB interface between the FPGA and the external world. For example, it can be programmed to generate TTL signals, CMOS signals, PCI signals, ... The IOB also have some flip-flop, so that the output from a flip-flip to the external world take less time (in the order of a few nanoseconds). However, IOB doesn't contain any logic functions, as they are in logic cells.

Memory structures can be constructed from logic cells, but if you need a moderate amount of memory (more than 256 bytes), this will consume a lot of logic cells. This is why many FPGA contain what they call 'distributed RAM'. Some logic cells can be 're-programmed' as simple RAM structure (this is really FPGA-dependent). And some FPGA have dedicated RAM blocks (in the order of 4K to 16K bits, configurable for example as 512x8 bits, or 512 bytes). For higher memore requirement (like 256K or RAM) you need to use external RAM. FPGA isn't a RAM device, and doesn't provice much RAM. This is to save FPGA chip space for logic design. However, FPGA RAM is good for example for implementing level-1 cache.

To desing an FPGA project, you need a specialized program set. The program take some input files and generate output for the FPGA. Think of those input files as source code (analog to a 'cpp' file for C++ compilers). However, 'cpp' and other software-targetted language can't handle hardware designs. This is because in software, every instructions are ment to be followed using a sequential structure. In hardware, every modules work in parallel. So, a specialized language is needed, a language that can describe the hardware, an hardware description language (HDL). Two of the most popular languages are VHDL and VerilogHDL. They are as different as in Pascal and C. They both achieve the same result, they both have strength and weakness. If you know one, you have to re-learn if you wish to use the other, but the basic structure share some similarity.

VHDL is very popular, and is one of the first language written. However, it have been written long ago, and therefore, have encounteres several modifications to meet the industry requirements (FPGA). Verilog on the other hand is newer. It have less support, but is, in my opinion, easier to learn. If you have knowledge of programing language, like C, it will be easier to learn. Verilog is growing very fast in popularity, and is supported by most FPGA software programs. VHDL is much more textual (needing a lot of text to tell only a few things), however, it have more support (i.e., you'll find more source codes and examples written in VHDL).

So, what you need is to learn HDL, a set of tools to 'compile' the HDL to binary file (for FPGA), an FPGA and a way to program the binary file to the FPGA. Actually, the binary file is sent to a configuration memory (a flash), that is 'loaded' by the FPGA when it start. Optionally, you can manually send the program directly to the FPGA, but this is not suitable for stand-alone operations.

Many boards come with an FPGA configurator memory, but watch to make sure it have, unless you wish your board to be constantly connected to your PC, and hitting the 'download' button each time the FPGA is re-powered.

From here, you can look at FPGA basic tutorials, or if you wish, you can have a look at the different blocks of an FPGA described above (this is described in the manufacturer documents).

 

[ahsan]

First step to FPGA

hi

To begin with FPGA, first learn an HDL language like verilog or VHDL, VHDL is better than verilog, but it is difficult while verilog is easy specially for those who have background of C language. While learning HDL language, try to make small programs and then check them using a SIMULATOR (like veriloger, modelsim etc). After that move towards FPGA. As far as CHEAP KIT is concerned, the cheapest kit which i have seen was of 99$ having 100k gates.

 

[ojer25]

Re: First step to FPGA

Going through doccumentations may not be the best
sorry
i forget
i'm know too much about digital gates(AND,OR,NOT,...,FlipFlops
registers,counters...........)
and a little assembly language(for 8085),Qbasic, and VC++

 

[dddhacker]

Re: First step to FPGA

Hello

The best way to start is to read the

Programmable Logic Design Quick Start Hand Book

From xilinx. Go to xilinx.com and download it. IT is about 9 MB.

A very good book to start on FPGAs

 

[Mazi3]

Re: First step to FPGA

the best handbook to learn VHDL:
**broken link removed**
starts with schematics symbol(simple D-FF or counter) and then VHDL and Verilog description. You need basic knowledge of digital circuits(what does FF does, what does OR gate does, what is state machine...etc)

I learned how to program things in one month, from newbie, well, the details come later (like synchronous design!!! )

do that simple things in simulator to learn the language and get in touch with it )

good learning!

 

[craftfox]

First step to FPGA

Deponding on the FPGA product and development software, U can read the help document of them.

 

[davyzhu]

First step to FPGA

Recommend a good site for all of the hardware knowledge:
https://www.fpga4fun.com/

And a xilinx spartan3 starter kit is available on xilinx's website, it is cheap and have enough functions for beginners.

Bye,

Davy Zhu

 

[cxghlj]

First step to FPGA

Read document of productor may be the the quickly way to understand the flow of design and make good design ,but I think you must learn some basic kwonlege and some skills of transiver HDL languge to hardware.