Network Time Synchronization: A Full Hardware Approach

Complex digital systems are typically built on top of several abstraction levels: digital, RTL, computer, operating system and software application. Each abstraction level greatly facilitates the design task at the cost of paying in performance and hardware resources usage. Network time synchronization is a good example of a complex system using several abstraction levels since the traditional solutions are a software application running on top of several software and hardware layers. In this contribution we study the case where a standards-compliant network time synchronization solution is fully implemented in hardware on a FPGA chip doing without any software layer. This solution makes it possible to implement very compact, inexpensive and accurate synchronization systems to be used either stand-alone or as embedded cores. Some general aspects of the design experience are commented together with some figures of merit. As a conclusion, full hardware implementations of complex digital systems should be seen as a feasible design option, from which great performance advantages can be expected, provided that we can find a suitable set of tools and control the design development costs

Fast Hardware Implementations of Static P Systems

In this article we present a simulator of non-deterministic static P systems using Field Programmable Gate Array (FPGA) technology. Its major feature is a high performance, achieving a constant processing time for each transition. Our approach is based on representing all possible applications as words of some regular context-free language. Then, using formal power series it is possible to obtain the number of possibilities and select one of them following a uniform distribution, in a fair and non-deterministic way. According to these ideas, we yield an implementation whose results show an important speed-up, with a strong independence from the size of the P system.Ministry of Science and Innovation of the Spanish Government under the project TEC2011-27936 (HIPERSYS)European Regional Development Fund (ERDF)Ministry of Education of Spain (FPU grant AP2009-3625)ANR project SynBioTI

Inertial and Degradation Delay Model for CMOS Logic Gates

The authors present the Inertial and Degradation Delay Model (IDDM) for CMOS digital simulation. The model combines the Degradation Delay Model presented in previous papers with a new algorithm to handle the inertial effect, and is able to take account of the propagation and filtering of arbitrarily narrow pulses (glitches, etc.). The model clearly overcomes the limitations of conventional approaches

Modeling of Real Bistables in VHDL

A complete VHDL model of bistables including their metastable operation is presented. An RS-NAND latch has been modelled as a basic structure, orienting its implementation towards its inclusion in a cell library. Two applications are included: description of a more complex latch (D-type) and description of a circuit containing three latches where metastable signals are propagated. Simulation results show that the presented niodel provides very realistic information about the device behavior, which until now had to be obtained through electric simulation

Influence of Clocking Strategies on the Design of Low Switching-Noise Digital and Mixed-Signal VLSI Circuits

This communication shows the influence of clocking schemes on the digital switching noise generation. It will be shown how the choice of a suited clocking scheme for the digital part reduces the switching noise, thus alleviating the problematic associated to limitations of performances in mixed-signal Analog/Digital Integrated Circuits. Simulation data of a pipelined XOR chain using both a single-phase and a two-phase clocking schemes, as well as of two nbit counters with different clocking styles lead, as conclusions, to recommend multiple clock-phase and asynchronous styles for reducing switching noise

New CMOS VLSI Linear Self-Timed Architectures

The implementation of digital signal processor circuits via self-timed techniques is currently a valid altemative to solve some problems encountered in synchronous VLSI circuits. However; a main difference between synchronous and asynchronous circuits is the hardware resources needed to implement asynchronous circuits. This communication presents four less-costly alternatives to a previously reported linear selftimed architecture, and their application in the design of FIFO memories. Furthermore, the integration and characterization in the laboratory of prototypes of these FIFOs are presented

NanoFS: a hardware-oriented file system

NanoFS is a novel file system for embedded systems and storage-class memories (like flash) and is specially designed to be directly implemented in hardware. NanoFS is based on an original internal layout intended to achieve an optimal hardware implementation of the file system’s file lookup and data fetch operations. File system spe-cification on a sample reader module completely implemented in a pro-grammable device is introduced

Delay degradation effect in submicronic CMOS inverters

This communication presents the evidence of a degradation effect causing important reductions in the delay of a CMOS inverter when consecutive input transition are close in time. Complete understanding of the effect is demonstrated, providing a quantifying model. Fully characterization as a function of design variables and external conditions is carried out, making the model suitable for using in library characterization as well as simulation at a transistor level. Comparison with HSPICE level 6 simulations shows satisfactory accuracy for timing evaluation.Comisión Interministerial de Ciencia y Tecnología TIC 95-009

Minimalistic SDHC-SPI hardware reader module for boot loader applications

This paper introduces a low-footprint full hardware boot loading solution for FPGA-based Programmable Systems on Chip. The proposed module allows loading the system code and data from a standard SD card without having to re-program the whole embedded system. The hardware boot loader is processor independent and removes the need of a software boot loader and the related memory resources. The hardware overhead introduced is manageable, even in low-range FPGA chips, and negligible in mid- and high-range devices. The implementation of the SD card reader module is explained in detail and an example of a multi-boot loader is offered as well. The multi-boot loader is implemented and tested with the Xilinx's Picoblaze microcontroller