Desynchronization: Synthesis of asynchronous circuits from synchronous specifications

Asynchronous implementation techniques, which measure logic delays at run time and activate registers accordingly, are inherently more robust than their synchronous counterparts, which estimate worst-case delays at design time, and constrain the clock cycle accordingly. De-synchronization is a new paradigm to automate the design of asynchronous circuits from synchronous specifications, thus permitting widespread adoption of asynchronicity, without requiring special design skills or tools. In this paper, we first of all study different protocols for de-synchronization and formally prove their correctness, using techniques originally developed for distributed deployment of synchronous language specifications. We also provide a taxonomy of existing protocols for asynchronous latch controllers, covering in particular the four-phase handshake protocols devised in the literature for micro-pipelines. We then propose a new controller which exhibits provably maximal concurrency, and analyze the performance of desynchronized circuits with respect to the original synchronous optimized implementation. We finally prove the feasibility and effectiveness of our approach, by showing its application to a set of real designs, including a complete implementation of the DLX microprocessor architectur

From FPGA to ASIC: A RISC-V processor experience

This work document a correct design flow using these tools in the Lagarto RISC- V Processor and the RTL design considerations that must be taken into account, to move from a design for FPGA to design for ASIC

Modular Acquisition and Stimulation System for Timestamp-Driven Neuroscience Experiments

Dedicated systems are fundamental for neuroscience experimental protocols that require timing determinism and synchronous stimuli generation. We developed a data acquisition and stimuli generator system for neuroscience research, optimized for recording timestamps from up to 6 spiking neurons and entirely specified in a high-level Hardware Description Language (HDL). Despite the logic complexity penalty of synthesizing from such a language, it was possible to implement our design in a low-cost small reconfigurable device. Under a modular framework, we explored two different memory arbitration schemes for our system, evaluating both their logic element usage and resilience to input activity bursts. One of them was designed with a decoupled and latency insensitive approach, allowing for easier code reuse, while the other adopted a centralized scheme, constructed specifically for our application. The usage of a high-level HDL allowed straightforward and stepwise code modifications to transform one architecture into the other. The achieved modularity is very useful for rapidly prototyping novel electronic instrumentation systems tailored to scientific research.Comment: Preprint submitted to ARC 2015. Extended: 16 pages, 10 figures. The final publication is available at link.springer.co

6502 emulator on FPGA

6502 microprocessor was once used in almost all of the microcomputer in the 80s, including the Apple II lines of computer, the Commodore PET, the Commodore 64, the Atari 8-bit series and even on the Nintendo Entertainment System (NES) video game console. The objective of this project is to emulate the once famous 6502 microprocessor onto a FPGA chip. The FPGA-based 6502 microprocessor had to emulate the functionality of a real 6502 microprocessor. Accurate pinouts emulation is desired but not a must. The 6502 assembly language is easy to learn and building a computer based on this microprocessor requires very few parts, thus making this project a great experiential learning process. The scope of this project requires the student to have an in-depth understanding on computer system architecture, especially on 6502 architecture; V erilog to understand existing 6502 source code from Bird Computer and also FPGA development process (synthesis tools) to transfer the Verilog code to the FPGA chip. Thus far, the resources and information on 6502 microprocessor looks promising. The student earlier scope was to come up with the 6502 code in Verilog HDL, but as there is available code from Bird Computer (State Machine coded) so the student had chanced his objectives to understand the existing code and implement it on FPGA only. But as along the way, problems occur on hardware implementation, focus had been switched again to simulate the existing code or ALU or simple processor to build up student understanding and for documentation for future project expansion. To test the functionality of the 6502 system, the student will either find existing application or come up with simple program to run using the FPGA-based 6502 system

High-level asynchronous system design using the ACK framework

Journal ArticleDesigning asynchronous circuits is becoming easier as a number of design styles are making the transition from research projects to real, usable tools. However, designing asynchronous "systems" is still a difficult problem. We define asynchronous systems to be medium to large digital systems whose descriptions include both datapath and control, that may involve non-trivial interface requirements, and whose control is too large to be synthesized in one large controller. ACK is a framework for designing high performance asynchronous systems of this type. In ACK we advocate an approach that begins with procedural level descriptions of control and datapath and results in a hybrid system that mixes a variety of hardware implementation styles including burst-mode AFSMs, macromodule circuits, and programmable control. We present our views on what makes asynchronous high level system design different from lower level circuit design, motivate our ACK approach, and demonstrate using an example system design

Efficacy of Multi-Threshold NULL Convention Logic in Low-Power Applications

In order for an asynchronous design paradigm such as Multi-Threshold NULL Convention Logic (MTNCL) to be adopted by industry, it is important for circuit designers to be aware of its advantages and drawbacks especially with respect to power usage. The power tradeoff between MTNCL and synchronous designs depends on many different factors including design type, circuit size, process node, and pipeline granularity. Each of these design dimensions influences the active power and the leakage power comparisons. This dissertation analyzes the effects of different design dimensions on power consumption and the associated rational for these effects. Results show that while MTNCL typically uses more active power and less leakage power than an equivalent synchronous design, the magnitude of this difference can vary greatly and trends can be observed across each of these different design dimensions. Using the results and analysis found in this work, circuit designers will be able to choose between MTNCL and synchronous architectures for a given target application based on anticipated power consumption differences

Application specific instruction set processor design for embedded application using the coware tool

An Application Specific Instruction Set Processor (ASIP) is widely used as a System on a Chip(SoC) Component. ASIPs possess an instruction set which is tai-lored to benefit a specific application. Such specialization allows ASIPs to serve as an intermediate between two dominant processor design styles- ASICs which has high processing abilities at the cost of limited programmability and Programmable solu-tions such as FPGAs that provide programming exibility at the cost of less energy eficiency. In this dissertation the goal is to design ASIP, keeping in mind a temper-ature sensor system. The platform used for processor design is LISA 2.0 description language and processor designing environment from CoWare. Coware processor de-signer allows processor architecture to be defined at an abstract level and automatic generation of chain of software tools like assembler, linker and simulator for functional verification followed by RTL level description. RTL level description is used to gen-erate synthesized report of the design using RTL compiler and finally the layout is created using Cadence encounter