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Archive for August, 2017

Introduction to Zynq™ Architecture

Friday, August 25th, 2017

The history of System-on-Chip (SoC)

Do we prefer to have a small electronic device or a larger one? The answer will often be “the smaller one”. However, before the commercialization of small radios, many people were interested in having big radios for the extravagance. Subsequently, at the beginning of the emergence of compact radios, those who preferred the flamboyance of large radios refused using compact radios. Slowly, but surely, the overwhelming benefits of owning a more compact radio led to the proliferation of smaller devices. These days the progression of the technology enables cutting-edge companies to encapsulate different parts of a system into increasingly smaller devices, all the way down to a single chip, which added the System-on-Chip (SoC) concept to the electronics world. By way of an example of a SoC, I will explain the Zynq-7000 all-programmable SoC. It consists of two hard processors, programmable logic (PL), ADC blocks and many other features all in one silicon chip.

Before the invention of the Zynq, processors were coupled with a Field Programmable Gate Array (FPGA) which made communication between the Programmable Logic (PL) and Processing System (PS) complicated. The Zynq architecture, as the latest generation of Xilix’s all-programmable System-on-Chip (SoC) families, combines a dual-core ARM Cortex-A9 with a traditional (FPGA). The interface between the different elements within the Zynq architecture is based on the Advanced eXtensible Interface (AXI) standard, which provides for high bandwidth and low latency connections.

Before implementing the ARM processor inside the Zynq device, users were using a soft core processor such as Xilinx’s Microblaze. The main advantage of using Microblaze was, and remains, the flexibility of the processor instances within a design. On the other hand, the inclusion of hard processor in Zynq delivers significant performance improvements. Also, by simplifying the system to a single chip, the overall cost and physical size of the device are reduced.

Zynq Design Flow

The design flow for the Zynq architecture has some steps in common with a regular FPGA. The first stage is to define the specifications and requirements of the system. Next, during the system design stage, the different tasks (functions) are assigned to implementation in either PL or PS which is called task partitioning. This stage is important because the performance of the overall system will depend on tasks/functions being assigned for implementation in the most appropriate technology: hardware or software. For the rest of this article, visit the Aldec Design and Verification Blog.

Tags: ARM, embedded, FPGA, hardware, SoC and ASIC Prototyping
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Accelerating Simulation of Vivado Designs with HES

Friday, August 11th, 2017

FPGA Design Verification Challenge

The FPGA design and verification “ecosystem” changes rapidly to keep pace with the fast growing size of FPGA devices. The largest Xilinx Virtex UltraSCALE chips provide 4.4 Million logic cells or using another metric 50 million equivalent gate count.

To enable efficient design process for Virtex-7 and newer UltraSCALE FPGAs, Xilinx provides software called Vivado Design Suite. Besides supporting a classical HDL design flow, it also provides system level design tools like IP Integrator, System Generator or even High Level Synthesis, that are very convenient for designing large and complex designs.

Verification has always taken a significant share of the project schedule with HDL simulation being the main stage of that process. With such big designs however, even the fastest simulators would spend hours in simulation tasks.

Simulation Acceleration with HES-DVM™

Aldec’s HES-DVM bridges this gap enabling accelerated simulation with the design running in the FPGA and the testbench in the simulator.

Aldec has been providing HES™ – Hardware Emulation Solutions since 2001. During that time the HES evolved to address the most sophisticated design requirements and fulfill customers’ requirements. Thus, simulation acceleration is only one example of how HES can be used with other applications being hybrid co-emulation, in circuit emulation, and physical prototyping.

With simulation acceleration the user can move any synthesizable module from simulator to the FPGA thus offload some processing from the HDL simulator. Typically, an entire design is implemented in HES board and the simulator only executes the testbench.

Figure 1: Signal-level simulation acceleration

The HES boards are seamlessly integrated with the simulator with PCI Express x8 physical connection to the host workstation. The HES-DVM provides co-simulation interfaces for Aldec’s Riviera-PRO and Active-HDL simulators but also for other 3^rd party simulators. It can be used both in Linux and Windows operating systems with all required PCIe drivers and interfaces working out of the box.

The DVM tool automates the process of design compilation and implementation for HES boards. It generates all necessary scripts and configuration files to run simulation acceleration in a given HES board but also brings many useful debugging features. Despite running your design in FPGA hardware you can keep simulation level visibility with an RTL View of all internal probes.

Figure 2: Design setup flow for acceleration using DVM™

Acceleration Benchmark

MIG controller for DDR3, AXI interconnect, two AXI traffic generators and one AXI protocol checker as shown in the following diagram.How much acceleration can I achieve? This is always the first customer’s question and frankly there is no straight answer because the result depends on the complexity of both the design and the testbench. Usually a good estimation can be obtained from running simulation profiling and then applying Amdahl’s rule. However, the best way to verify acceleration potential is just to experiment with a typical design, so we have created a simple design of a memory sub-system using Xilinx Vivado Design environment. It contains MIG controller for DDR3, AXI interconnect, two AXI traffic generators and one AXI protocol checker as shown in the following diagram.

Figure 3: Diagram created for memory subsystem benchmarking

Benchmark Results

Workstation and software used for benchmarking:

Workstation:
CPU: Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz
RAM: 32 GB
HES Board: HES7XV4000BP_REV2, contains 2x Virtex7 2000 FPGA

Software:
OS: Linux CentOS 6, x86_64
Simulator: Riviera-PRO 2017.02
Design env: Vivado 2016.4
Acceleration env: HES-DVM 2017.02

If you are interested in further details about this project, benchmark, and tools which can significantly accelerate your simulation you can view the following application note: https://www.aldec.com/en/support/resources/documentation/articles/1915

Tags: acceleration, co-simulation, FPGA, HES-DVM, simulation, SoC and ASIC Prototyping, verification, Xilinx
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Traceability Matrices: Headache or Real Value

Wednesday, August 2nd, 2017

Traceability is becoming increasingly important in most engineering projects, if only on the grounds of ‘good practice’, and it is specifically required for projects that have to meet safety standards such as DO-254 and ISO 26262.

To provide traceability, you must maintain the relationships between all aspects of a project; from the system-level requirements through implementation and verification. Unfortunately, many organizations reduce their traceability responsibilities to preparing a few matrices for major reviews and to comply with respective safety standards. Such an approach is very time-consuming and I would argue it does little if anything to improve the overall management of the project. Or the design for that matter.

Good traceability data helps prevent errors and omissions in specifications, design and test plans. The first step is to define a traceability model.