Most new FPGA designs incorporate one or more hard and soft core processors. Arm’s AXI4 interconnect is one way to add peripheral support. The PYNQ-Z1 board is designed to be used with PYNQ, a new open-source framework that enables embedded programmers to exploit the capabilities of Xilinx. This article explains pipelining and its implications with respect to FPGAs, i.e., latency, throughput, change in operating frequency, and.

Author: Togar Gulkis
Country: Ethiopia
Language: English (Spanish)
Genre: Education
Published (Last): 21 September 2014
Pages: 224
PDF File Size: 15.81 Mb
ePub File Size: 16.6 Mb
ISBN: 400-4-38214-355-9
Downloads: 85660
Price: Free* [*Free Regsitration Required]
Uploader: Voodoobar

February 15, by Sneha H. This article explains pipelining and its implications with respect to FPGAs, i. Programming an FPGA field programmable gate array fpg a process of customizing its resources to implement a definite logical function. During the design process, one important criterion to be taken into account is the timing issue inherent in the system, as well as any constraints laid down by the user. Pipelining is a process which enables parallel execution of program instructions.

You can see a visual representation of a pipelined processor architecture below. In FPGAs, this is achieved by arranging multiple data processing blocks in a particular fashion.


For this, we first divide our overall logic circuit into several small parts and then separate them using registers flip-flops. Let’s analyze the mode in which an FPGA design is pipelined by considering an example. Let’s take a look at a system of three multiplications followed by one addition on four input arrays. In the second clock tick, there would be valid data at the input pins of both M 1 and M 2. When the clock ticks for the third time, there would be valid inputs at all the three components: This nedjr the first output of the system will be available after the third clock tick.

Next, as the fourth clock tick arrives, M 1 can operate over the next set of necir But at this instant, M 2 and A 1 are expected to be idle. When a similar excitation pattern is followed for the components, we can expect the next outputs to occur at clock ticks 9, 12, 15 and so on Figure 2b.

Elbert V2 – Spartan 3A FPGA Development Board | Numato Lab

Here, at the first clock tick, valid inputs appear only for registers R 1 through R 4 a 1b 1c 1 and d 1respectively and for the multiplier M 1 a 1 and b 1. As a result, only these can produce valid outputs. Moreover, once M 1 needir its output, it is passed on to register R 5 and stored in it. Meanwhile, even the second set of data a 2b 2c 2and d 2 enters into the system and appears at the outputs of R 1 through R 4. This is because, in this design, any change in the output of M 1 does not affect the output of M 2.


This means insertion of register R 5 has made M 1 and M 2 functionally independent due to which they both can operate on different sets of data at the same time. Nevertheless, at the same clock tick, M 1 and M 2 will be free to operate on a 3b 3 and a 2b 2c 2respectively. This is feasible due to the presence of registers R 5 isolating block M 1 from M 2 and R 8 isolating fppga M 2 from adder A 1.

On following the same mode of operation, we can expect one output data to appear for each clock tick from then on Figure 3bunlike in the case of non-pipelined design where we had to wait for three clock cycles to get each single output data Figure 2b.

In the example shown, pipelined design jedir shown to produce one output for each clock tick from third clock cycle. This is because each input nedirr to pass through three registers constituting the fpha depth while being processed before it arrives at the output.

Similarly, if we have a pipeline of depth nthen the valid outputs appear one per clock cycle only from n th clock tick.

The Why and How of Pipelining in FPGAs

This delay associated with the number of clock cycles lost before the first valid output appears is referred to as latency. The non-pipelined design shown in Figure 2a is shown to ndir one output for every three clock cycles. This longest data path would then be the critical path, which decides the minimum operating clock frequency of our design. In the pipelined design, once the pipeline fills, there is one output produced for every clock tick.

A pipelined design yields one output per clock nedlr once latency is overcome irrespective of the number of pipeline stages contained in the design.

Hence, by designing a pipelined system, we can increase the throughput of an FPGA. In pipelining, we use registers to store the results of the individual stages of the design.

These components add on to the logic resources used by the design and make it quite huge in terms of hardware. The act of pipelining a design is quite exhaustive. You need to divide the overall system into individual stages at adequate instants to ensure optimal performance. Nevertheless, the hard work that goes into it is on par with the advantages it renders while the design executes. I have read many articles about pipeline and been instructed by my supervisor.


But this is the first time i have understood it totally. IMHO incorrect, because multiplier produces stable fpta after a given time delay, dependent on longest combinational path which in turn is technology and architecture dependentwhich has nothing to do with clock frequency. In other terms, one can supply a clock with such frequency that the circuit in Fig 2a will have steady output in one or more clock cycles.

Signal propagation time determines highest applicable clock frequency, not the other way around. Rather, it applies to a system that is based on the one in Figure 2a but has been modified to ensure synchronous operation. The synchronous version would have clock-driven storage elements that prevent A1 from producing a valid output during the first clock cycle. Clearly, the author meant that the circuit Fig. If the inputs are made available simultaneously, M1 will produce a valid output after its propagation nwdirthen M2 will produce a valid output, then A1 will produce a valid output.

The A1 output could then be neddir in a register, and a new multiplication operation could be performed. Only one clock cycle is required with the clock period chosen according to the fpba delays. It seems to me that in this particular nediir pipelining does not offer a major improvement in performance. Au contraire, since maximum frequency for nrdir in Fig.

OK, necir makes sense.

Pipelining allows you to establish the clock frequency according to the propagation delay of just one stage, instead of the total propagation delay. It looks like we need to revise this article. Contact me via e-mail in weeks. For complex pipeline designs, where information is split nedit multiple parallel branches and then combined back it may be difficult to keep the same latency in all paths. That problem is addressed in neeir graphical environments e.

I have faced that in a few of my projects, and tried to create an automated solution. You may find the Open Source implementation at https: It is also described in my paper http: You May Also Like: T Is for Toggle: Understanding the T Flip-Flop This tech brief provides an overview of a somewhat uncommon member of the flip-flop family. I am happy to know that my article served your purpose.

The best explanation of pipelining concept. Apologies if the formatting messes up.

Quote of the day.