Latch是电平触发的存储单元。 •锁存器的缺点(1),对毛刺敏感,使能信号有效时,输出状态可能随输入状态多次变化,产生空翻,对下一级电路很危险。(2)不能异步复位,上电后处于不确定状态。(3),锁存器会使STA变得非常复杂,(4)综合工具会将latch优化掉,造成前后仿真不一致。(5),FPGA的基本单元是由查找表和触发器...
//正确示例1:moduletop_module(input[15:0]scancode,outputregleft,outputregdown,outputregright,outputregup);always@(*)beginup=1'b0;down=1'b0;left=1'b0;right=1'b0;//缺少default时,可以通果赋初值避免形成Latch,always块中阻塞初赋值(逐行执行),打断Latch环case(scancode)16'he06b:left=1'b1;16'...
The next interesting structure is a transparent latch; it will pass the input to the output when the gate signal is set for “pass-through”, and captures the input and stores it upon transition of the gate signal to “hold”. The output will remain stable regardless of the input signal ...
// File Name : LATCH_N.v// Module Name : LATCH_N// Description : This is a latch module.// Project ://===module LATCH_N(//Input ports.DATA_IN,LATCH_EN,//Output ports.DATA_OUT);//===//Input and output declaration//===...
// This code will generate a latchinput[1:0] x;reg[1:0] y;always@(*)beginif(x ==2'b10) y =2'd3;elseif(x ==2'b11) y =2'd2;end// y has a default value so that this code will not generate a latchalways@(*)beginy =2'b00;if(x ==2'b10) ...
21.Timing Analysis does not support the analysis of latches as synchronous elements for the currently selected device family 原因:用analyze_latches_as_synchronous_elements setting可以让Quaruts II来分析同步锁存,但目前的器件不支持这个特性 措施:无须理会。时序分析可能将锁存器分析成回路。但并不一定分析正...
The description style you are using to describe a register or latch is not supported in the current software release. 具体代码来源是这个网址 https://www.cnblogs.com/vv123/p/17436195.html#5333441 再修改了一些小错误后报错这个,我自己不会改正,恳请大佬们指点迷津。具体平台是ISE,使用verilog语言。
避免latch锁存器的产生 循环语句 四类循环语句 forever语句 repeat语句 while语句 for语句 块语句 顺序块(也称过程块) 并行块语句 命名块 嵌套块 命名块的禁用 生成块 循环生成语句 条件生成语句 case生成语句 赋值语句 在Verilog HDL语言中,信号有两种赋值方式: ...
组合逻辑(如逻辑门)不能记住任何状态。注意:类似“Warning (10240): ... inferring latch(es)”这样的警告信息基本上代表有故障,除非这个latch是故意生成的。组合电路必须为所有输出在所有条件下分配一个值。这通常意味着您总是需要为输出分配else子句或默认值。
Your circuit has one 16-bit input, and four outputs. Build this circuit that recognizes these four scancodes and asserts the correct output. To avoid creating latches, all outputs must be assigned a value in all possible conditions (See also always_if2). Simply having a default case is no...