基于MSP430F149单片机的SDRAM控制程序设计

本文介绍了德州仪器公司新一代16位Flash型MSP430F149系列单片机的结构、特性和功能,阐述了基于该单片机控制系统的硬件组成和软件设计,并给出了该控制器在SDRAM控制系统中的应用,具有功耗低、功能齐全、人机界面友好等优点。

SDRAM控制器的设计及其应用

介绍了SDRAM存储器的工作原理及控制特点,描述了SDRAM控制器软核的设计方法,阐述了基于VHDL语言的状态机实现SDRAM控制器的关键技术,并给出了该控制器在HIRFL-CSR数据获取控制系统中的应用。

SDRAM控制器的设计及其在CSR控制系统中的应用

在国家重大科学工程HIRFL-CSR的控制系统中，高速数据获取单元或非线性过程控制器常用到数据缓冲存储器。采用集成度高、功耗低、可靠性高、处理能力强的同步动态随机存储器SDRAM，是最好的选择。但是，与速度快、控制简单的SRAM相比，SDRAM存储器有复杂的时序要求，需要定时刷新，为此，必须设计SDRAM控制器。为了降低系统成本，采用FPGA技术，并使用VHDL语言设计和实现SDRAM控制器。论文首先介绍了存储器的结构和原理，SDRAM控制器的结构和组成，FPGA技术及其配置方法和VHDL语言的基本概念。随后详细介绍了SDRAM控制器基本结构的建立、符合PC133规范的硬件设计方案和软件的实现。其次，介绍了串口和SDRAM控制器的设计开发平台，并实现对SDRAM存储器的数据读写和刷新。另外，还介绍了与计算机进行串口通信的设计。 最后，介绍了利用FPGA实现DSP与SDRAM的接口电路设计及其在HIRFL-CsR控制系统中的应用。整个论文的工作完成了CSR控制系统中SDRAM控制器的硬件设计和VHDL程序编制、调试。为以后开发和实现控制系统的高速数据获取提供了一个原型。

High performance IP lookup circuit using DDR SDRAM

DDR-SDRAM based data lookup techniques are evolving into a core technology for packet lookup applications for data network, benefitting from the features of high density, high bandwidth and low price of DDR memory products in the market. Our proposed DDR-SDRAM based lookup circuit is capable of achieving IP header lookup for network line-rates of up to 10Gbps, providing a solution on high-performance and economic packet header inspections. ©2008 IEEE.

Reducing main memory access latency through SDRAM address mapping techniques and access reordering mechanisms

As the performance gap between microprocessors and memory continues to increase, main memory accesses result in long latencies which become a factor limiting system performance. Previous studies show that main memory access streams contain significant localities and SDRAM devices provide parallelism through multiple banks and channels. These locality and parallelism have not been exploited thoroughly by conventional memory controllers. In this thesis, SDRAM address mapping techniques and memory access reordering mechanisms are studied and applied to memory controller design with the goal of reducing observed main memory access latency. The proposed bit-reversal address mapping attempts to distribute main memory accesses evenly in the SDRAM address space to enable bank parallelism. As memory accesses to unique banks are interleaved, the access latencies are partially hidden and therefore reduced. With the consideration of cache conflict misses, bit-reversal address mapping is able to direct potential row conflicts to different banks, further improving the performance. The proposed burst scheduling is a novel access reordering mechanism, which creates bursts by clustering accesses directed to the same rows of the same banks. Subjected to a threshold, reads are allowed to preempt writes and qualified writes are piggybacked at the end of the bursts. A sophisticated access scheduler selects accesses based on priorities and interleaves accesses to maximize the SDRAM data bus utilization. Consequentially burst scheduling reduces row conflict rate, increasing and exploiting the available row locality. Using a revised SimpleScalar and M5 simulator, both techniques are evaluated and compared with existing academic and industrial solutions. With SPEC CPU2000 benchmarks, bit-reversal reduces the execution time by 14% on average over traditional page interleaving address mapping. Burst scheduling also achieves a 15% reduction in execution time over conventional bank in order scheduling. Working constructively together, bit-reversal and burst scheduling successfully achieve a 19% speedup across simulated benchmarks.

Per-Flow State Management Technique for High-Speed Networks

Flow processing is a fundamental element of stateful traffic classification and it has been recognized as an essential factor for delivering today’s application-aware network operations and security services. The basic function within a flow processing engine is to search and maintain a flow table, create new flow entries if no entry matches and associate each entry with flow states and actions for future queries. Network state information on a per-flow basis must be managed in an efficient way to enable Ethernet frame transmissions at 40 Gbit/s (Gbps) and 100 Gbps in the near future. This paper presents a hardware solution of flow state management for implementing large-scale flow tables on popular computer memories using DDR3 SDRAMs. Working with a dedicated flow lookup table at over 90 million lookups per second, the proposed system is able to manage 512-bit state information at run time.