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本科毕业设计（论文）
基于FPGA的计时器的设计
学 院 自动化学院 专 业 电子信息科学与技术 年级班别 2009级(1)班 学 号 3109001158 学生姓名 刘健忠 指导教师 谭北海
2013年4月
基于 F P G A 的计 时器 设 计
刘 健忠
自 动化 学院
摘 要
随着电子设计自动化技术和可编程逻辑器件的出现和飞速发展，在设计周期得到大大的缩短的同时系统成本也有了大幅度的降低，显然标准逻辑器件的组装已远不能满足这方面的要求。而Verilog HDL能提供高阶电路描述语言的方式，让复杂的电路可以通过Verilog HDL编辑器的电路合成方式，轻易而且快速的达到设计的规格。由于Verilog HDL电路描述语言能涵盖的范围相当广，能适用于各种不同阶层的设计工程师的需要，所以Verilog HDL电路设计毫无疑问的成为硬件设计工程师的必备工具。
本系统是用Verilog编写的基于Altera DE2的电话计费器。该设计采用了现场可编程逻辑器件FPGA设计，并基于硬件描述语言Verilog HDL在Altera公司的Quartus Ⅱ软件上实现仿真。根据电话局反馈回来的信号，此信号是提前预设的，数码管显示通话类型、用户余额以及通话时长（包括秒数和分钟数）。根据每种通话类型的计费价格不同，当系统所设置的余额数不够，用户将无法拨通电话，当用户余额小于指定金额时，系统发出警告信号，提醒用户。当告警时间过长（超过1分钟）时自动切断通话信号。当用户结束通话，系统清零。
关键词：Verilog ，FPGA，通话信号，计时器
Abstract
With the rapid development of electronic design automation technology and
programmable logic devices which greatly shorten the design period and reduced the cost of the system at the same time. Apparently, the assembly of standard logic devices can not meet the requirements in this regard. Verilog HDL can provide high-level circuit description language, which allows complex circuit by the Verilog HDL Editor circuit synthesis method as well by meeting the design specification appropriately. Verilog HDL circuit description language covers a very wide range,which can be applied to a variety of different sectors of the needs of design engineers, the circuit design of Verilog HDL without a doubt to become an essential tool for hardware design engineers.
The system is based on Altera DE2 written by Verilog phone devices. It is used by Field Programmable Gate Array FPGA based on Verilog HDL hardware description language to design and Altera's Quartus Ⅱ in software for emulation. According to the feedback of the telephone office back signal which is actually pre-designed, digital pipe display type, user balance and phone call duration (including the number of seconds or minutes). Depending on the billing price of each call type is different,when a began to balance the set is not enough, the user will not be able to dial the phone, and when the balance is less than the specified money, issuing a warning signal system, reminding to users. When the alarm time is too long (more than 1 minutes), the conversation signal will be automatically cut off . When the user end the call, the system will be reseted.
Key words：Verilog ,FPGA,Calling signal,calculagraph