Identifying opportunities for dynamic circuit specialization

This work describes the identification of designs that benefit from a Dynamic Circuit Specialization (DCS) implementation on FPGAs. In DCS, the circuit is specialized for slowly changing inputs, called parameters. For certain applications or cores, a DCS implementation is faster and smaller than the original implementation. However, the best DCS implementation can be hard to identify, as it requires the designer to be familiar with both the design and DCS. In this paper, we present a profiling tool to aid the designer in analyzing the feasibility of a DCS implementation. It automatically provides a functional density estimate for the most interesting DCS implementations

Memory-efficient and fast run-time reconfiguration of regularly structured designs

Previous work has shown that run-time reconfiguration of FPGAs benefits greatly from the use of Tunable LUT (TLUT) circuits. These can be rapidly transformed into a specialized LUT circuit and are also very memory efficient when representing regularly structured designs, where the same hardware module is instantiated many times. However, the memory requirements and reconfiguration time of a run-time reconfigurable application are also dependent on the reconfiguration mechanism. In this paper, we will show that the memory requirements of conventional ICAP reconfiguration grow very fast with the number of modules, resulting in excessive memory usage. We propose to use Shift-Register-LUT (SRL) reconfiguration which is faster and results in a memory usage that is independent of the number of modules

A dynamically reconfigurable pattern matcher for regular expressions on FPGA

In this article we describe how to expand a partially dynamic reconfig- urable pattern matcher for regular expressions presented in previous work by Di- vyasree and Rajashekar [2]. The resulting, extended, pattern matcher is fully dynamically reconfigurable. First, the design is adapted for use with parameterisable configurations, a method for Dynamic Circuit Specialization. Using parameteris- able configurations allows us to achieve the same area gains as the hand crafted reconfigurable design, with the benefit that parameterisable configurations can be applied automatically. This results in a design that is more easily adaptable to spe- cific applications and allows for an easier design exploration. Additionally, the pa- rameterisable configuration implementation is also generated automatically, which greatly reduces the design overhead of using dynamic reconfiguration. Secondly, we propose a number of expansions to the original design to overcome several limitations in the original design that constrain the dynamic reconfigurability of the pattern matcher. We propose two different solutions to dynamically change the character that is matched in a certain block. The resulting pattern matcher, after these changes, is fully dynamically reconfigurable, all aspects of the implemented regular expression can be changed at run-time

Reducing the dynamic FPGA reconfiguration overhead

Dynamic hardware generation reduces the number of FPGA resources needed and speeds up the application by optimizing the configuration for the exact problem at hand at run-time. If the problem changes, the system needs to be reconfigured. When this occurs too often, the total reconfiguration overhead is too high and the benefit of using dynamic hardware generation vanishes. Hence, it is important to minimize the number of reconfigurations

A novel tool flow for increased routing configuration similarity in multi-mode circuits

A multi-mode circuit implements the functionality of a limited number of circuits, called modes, of which at any given time only one needs to be realised. Using run-time reconfiguration (RTR) of an FPGA, all the modes can be time-multiplexed on the same reconfigurable region, requiring only an area that can contain the biggest mode. Typically, conventional run-time reconfiguration techniques generate a configuration of the reconfigurable region for every mode separately. This results in configurations that are bit-wise very different. Thus, in this case, many bits need to be changed in the configuration memory to switch between modes, leading to long reconfiguration times. In this paper we present a novel tool flow that retains the placement of the conventional RTR flow, but uses TRoute, a reconfiguration-aware connection router, to implement the connections of all modes simultaneously. TRoute stimulates the sharing of routing resources between connections of different modes. This results in a significant increase in the similarity between the routing configurations of the modes. In the experimental results it is shown that the number of routing configuration bits that needs to be rewritten is reduced with a factor between 2 and 4 compared to conventional techniques

An automatic tool flow for the combined implementation of multi-mode circuits

A multi-mode circuit implements the functionality of a limited number of circuits, called modes, of which at any given time only one needs to be realised. Using run-time reconfiguration of an FPGA, all the modes can be implemented on the same reconfigurable region, requiring only an area that can contain the biggest mode. Typically, conventional run-time reconfiguration techniques generate a configuration for every mode separately. To switch between modes the complete reconfigurable region is rewritten, which often leads to very long reconfiguration times. In this paper we present a novel, fully automated tool flow that exploits similarities between the modes and uses Dynamic Circuit Specialization to drastically reduce reconfiguration time. Experimental results show that the number of bits that is rewritten in the configuration memory reduces with a factor from 4.6X to 5.1X without significant performance penalties

RecoNoC: a reconfigurable network-on-chip

This article presents the design of RecoNoC: a compact, highly flexible FPGA-based network-on-chip (NoC), that can be easily adapted for various experiments. In this work, we enhanced this NoC with dynamically reconfigurable shortcuts. These can be used to alter the NoC's topology to adapt to the system's communication needs. The design has been implemented and tested on a Xilinx Virtex-2 Pro FPGA, using the TMAP dynamic datafolding toolflow to automatically generate the reconfigurable hardware and the software reconfiguration procedures. The results show that, using dynamic datafolding, the overhead of introducing this shortcut mechanism is limited

Bouw een intelligente robot in de klas met Dwengo

Elektronica is niet meer weg te denken uit onze samenleving: niet enkel computers en spelconsoles, maar ook alledaagse huishoudtoestellen of auto’s zitten vandaag vol met micro-controllers. We staan er niet bij stil dat in elk van die micro-controllers een programmaatje loopt dat er voor zorgt dat alles correct werkt in interactie met de omgeving. Informatica in actie, dus. Dwengo vzw brengt micro-controllers naar het onderwijs. Leerlingen uit het voortgezet onderwijs bouwen zelf een intelligente robot in de klas. Daarbij ervaren ze hoe software bijzonder praktische en fysieke impact kan hebben. Al doende passen de leerlingen alle concepten toe die ze in de inforamticales hebben geleerd. Uit onze ervaringen blijkt dat het werken met robots leerlingen motiveert om het beste van zichzelf te geven

Maximizing the reuse of routing resources in a reconfiguration-aware connection router

Parameterised configurations for FPGAs are configuration bitstreams of which some of the bits are defined as Boolean functions of parameters. By evaluating these Boolean functions using different parameter values, it is possible to quickly and efficiently derive specialised configuration bitstreams with different properties. Generating and using parameterized configurations requires a new tool flow. In this paper we propose a novel algorithm for the routing step of this tool flow. This new router, called the connection bundle router, is able to route a circuit with parameterized interconnections. It produces routing solutions in less time (up to a factor 5,2) and with a better quality in terms of number of wires (up to 38%) and minimum track width (up to 25%) than its predecessors. The connection bundle router is fully automated and uses a scalable connection-based representation for the parameterized interconnections in a tunable circuit

A connection-based router for FPGAs

The FPGA's interconnection network not only requires the larger portion of the total silicon area in comparison to the logic available on the FPGA, it also contributes to the majority of the delay and power consumption. Therefore it is essential that routing algorithms are as efficient as possible. In this work the connection router is introduced. It is capable of partially ripping up and rerouting the routing trees of nets. To achieve this, the main congestion loop rips up and reroutes connections instead of nets, which allows the connection router to converge much faster to a solution. The connection router is compared with the VPR directed search router on the basis of VTR benchmarks on a modern commercial FPGA architecture. It is able to find routing solutions 4.4% faster for a relaxed routing problem and 84.3% faster for hard instances of the routing problem. And given the same amount of time as the VPR directed search, the connection router is able to find routing solutions with 5.8% less tracks per channel