我会在此基础上继续添加
注：http://www.eefocus.com/chudonganjin/blog/09-09/175772_9e67e.html#articletop
在QuartusII下进行编译和仿真的时候,会出现一堆warning,有的可以忽略,有的却需要注意,虽然按F1可以了解关于该警告的帮助,但有时候帮助解释的仍然不清楚,大家群策群力,把自己知道和了解的一些关于警告的问题都说出来讨论一下,免得后来的人走弯路.
下面是我收集整理的一些,有些是自己的经验,有些是网友的,希望能给大家一点帮助,如有不对的地方,请指正,如果觉得好,请版主给点威望吧,谢谢
1.Found clock-sensitive change during active clock edge at time on
register ""
原因：vector source
file中时钟敏感信号（如：数据，允许端，清零，同步加载等）在时钟的边缘同时变化。而时钟敏感信号是
不能在时钟边沿变化的。其后果为导致结果不正确。
措施：编辑vector source file
2.Verilog HDL assignment warning at : truncated value with size to
match size of target (
原因:在HDL设计中对目标的位数进行了设定,如:reg[4:0] a;而默认为32位,将位数裁定到合适的大小
措施:如果结果正确,无须加以修正,如果不想看到这个警告,可以改变设定的位数
3.All reachable assignments to data_out(10) assign '0', register
removed by optimization
原因:经过综合器优化后，输出端口已经不起作用了
4.Following 9 pins have nothing, GND, or VCC driving datain port --
changes to this connectivity may change fitting results
原因:第9脚，空或接地或接上了电源
措施:有时候定义了输出端口，但输出端直接赋‘0’，便会被接地，赋‘1’接电源。如果你的设计中这些端口就是这样用的，那便可以不理会这些warning
5.Found pins functioning as undefined clocks and/or memory
enables
原因:是你作为时钟的PIN没有约束信息。可以对相应的PIN做一下设定就行了。主要是指你的某些管脚在电路当中起到了时钟管脚的
作用，比如flip-flop的clk管脚，而此管脚没有时钟约束，因此QuartusII把“clk”作为未定义的时钟。
措施:如果clk不是时钟，可以加“not clock”的约束；如果是，可以在clock
setting当中加入；在某些对时钟要求不很高的情况下，可以忽略此警告或在这里修改:Assignments>Timing
analysis settings...>Individual
clocks...>...
注意在Applies to node中只用选择时钟引脚一项即可，required
fmax一般比所要求频率高5%即可，无须太紧或太松。
6.Timing characteristics of device EPM570T144C5 are
preliminary
原因:因为MAXII 是比較新的元件在 QuartusII 中的時序並不是正式版的,要等 Service Pack
措施:只影响 Quartus 的 Waveform
7.Warning: Clock latency analysis for PLL offsets is supported for
the current device family, but is not enabled
措施:将setting中的timing
Requirements&Option-->More Timing
Setting-->setting-->Enable Clock
Latency中的on改成OFF
8.Found clock high time violation at 14.8 ns on register
"|counter|lpm_counter:count1_rtl_0|dffs[11]"
原因:违反了steup/hold时间，应该是后仿真，看看波形设置是否和时钟沿符合steup/hold时间
措施:在中间加个寄存器可能可以解决问题
9.warning: circuit may not operate.detected 46 non-operational
paths clocked by clock clk44 with clock skew larger than data
delay
原因:时钟抖动大于数据延时,当时钟很快，而if等类的层次过多就会出现这种问题,但这个问题多是在器件的最高频率中才会出现
措施：setting-->timing
Requirements&Options-->Default
required fmax 改小一些，如改到50MHZ
10.Design contains input pin(s) that do not drive logic
原因:输入引脚没有驱动逻辑(驱动其他引脚）,所有的输入引脚需要有输入逻辑
措施:如果这种情况是故意的,无须理会,如果非故意,输入逻辑驱动.
11.Warning：Found clock high time violation at 8.9ns on node
'TEST3.CLK'
原因：FF中输入的PLS的保持时间过短
措施：在FF中设置较高的时钟频率
12.Warning: Found 10 node(s) in clock paths which may be acting as
ripple and/or gated clocks -- node(s) analyzed as buffer(s)
resulting in clock skew
原因:如果你用的 CPLD
只有一组全局时钟时，用全局时钟分频产生的另一个时钟在布线中当作信号处理，不能保证低的时钟歪斜(SKEW)。会造成在这个时钟上工作的时序电路不可靠，甚至每次布线产生的问题都不一样。
措施:如果用有两组以上全局时钟的 FPGA 芯片，可以把第二个全局时钟作为另一个时钟用，可以解决这个问题。
13.Critical Warning: Timing requirements were not met. See Report
window for details.
原因：时序要求未满足，
措施：双击Compilation Report-->Time
Analyzer-->红色部分（如clock
setup:'clk'等）-->左键单击list path,查看fmax的SLACK
REPORT再根据提示解决,有可能是程序的算法问题或fmax设置问题
14.Warning: Can't find signal in vector source file for input pin
|whole|clk10m
原因：这个时因为你的波形仿真文件（ vector source file ）中并没有把所有的输入信号(input pin)加进去，
对于每一个输入都需要有激励源的
15.Can't achieve minimum setup and hold requirement along path(s).
See Report window for details.
原因：时序分析发现一定数量的路径违背了最小的建立和保持时间，与时钟歪斜有关,一般是由于多时钟引起的
措施：利用Compilation Report-->Time
Analyzer-->红色部分（如clock hold:'clk'等），在slack中观察是hold
time为负值还是setup time 为负值，然后在：Assignment-->Assignment
Editor-->To中增加时钟名(from node finder)，Assignment
Name中增加和多时钟有关的Multicycle 和Multicycle Hold选项，如hold
time为负，可使Multicycle
hold的值>multicycle,如设为2和1。
16: Can't analyze file -- file E://quartusii/*/*.v is
missing
原因：试图编译一个不存在的文件，该文件可能被改名或者删除了
措施：不管他，没什么影响
17.Warning: Can't find signal in vector source file for input pin
|whole|clk10m
原因：因为你的波形仿真文件（ vector source file ）中并没有把所有的输入信号(input pin)加进去，
对于每一个输入都需要有激励源的
18.Error: Can't name logic function scfifo0 of instance "inst" --
function has same name as current design file
原因：模块的名字和project的名字重名了
措施：把两个名字之一改一下，一般改模块的名字
19.Warning: Using design file lpm_fifo0.v, which is not specified
as a design file for the current project, but contains definitions
for 1 design units and 1 entities in project Info: Found entity 1:
lpm_fifo0
原因：模块不是在本项目生成的，而是直接copy了别的项目的原理图和源程序而生成的，而不是用QUARTUS将文件添加进本项目
措施：无须理会，不影响使用
20.Timing characteristics of device are preliminary
原因：目前版本的QuartusII只对该器件提供初步的时序特征分析
措施：如果坚持用目前的器件，无须理会该警告。关于进一步的时序特征分析会在后续版本的Quartus得到完善。
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。但并不一定分析正确。其后果可能会导致显示提醒用户：改变设计来消除锁存器,但实际其实无关紧要
22.Warning:Found xx output pins without output pin load capacitance
assignment
原因：没有给输出管教指定负载电容
解决方法：该功能用于估算TCO和功耗，可以不理会，也可以在Assignment
Editor中为相应的输出管脚指定负载电容，以消除警告
续：
Process Statement warning at random.vhd(18): signal reset is in
statement, but is not in sensitivity list
----没把singal放到process（）中
pins ing as undefined clocks and/or memory enables
Info: Assuming node CLK is an undefined clock
-=-----可能是说设计中产生的触发器没有使能端
Interface Declaration error in clk_gen.vhd(29): interface object
"clk_scan" of mode out cannot be read. Change object mode to buffer
or inout.
------信号类型设置不对，out当作buffer来定义
instance "clk_gen1" instantiates undefined entity
"clk_gen"
-------引用的例化元件未定义实体－－entity
"clk_gen"
2 node(s) in clock paths which may be acting as ripple and/or gated
clocks -- node(s) analyzed as buffer(s) resulting in clock
skew
Info: Detected ripple clock "clk_gen:clk_gen1|clk_incr" as
buffer
Info: Detected ripple clock "clk_gen:clk_gen1|clk_scan" as
buffer
Process Statement warning at ledmux.vhd(15): signal or variable
"dataout" may not be assigned a new in every possible path through
the Process Statement. Signal or variable "dataout" holds its
previous in every path with no new assignment, which may create a
combinational loop in the current design.
Process Statement warning at divider_10.vhd(17): signal "cnt" is
read inside the Process Statement but isn't in the Process
Statement's sensivitity list
-----缺少敏感信号
clock transition on "counter_bcd7:counter_counter_clk|q_sig[3]"
register
Reduced register "counter_bcd7:counter_counter_clk|q_sig[3]" with
stuck clock port to stuck GND
Circuit may not operate. Detected 1 non-operational path(s) clocked
by clock "class[1]" with clock skew larger than data delay. See
Compilation Report for details.
Circuit may not operate. Detected 1 non-operational path(s) clocked
by clock "sign" with clock skew larger than data delay. See
Compilation Report for details.
error at counter_clk.vhd(90): actual port "class" of mode "in"
cannot be associated with formal port "class" of mode
"out"
------两者不能连接起来
Ignored node in vector source file. Can't find corresponding node
name "class_sig[2]" in design.
------没有编写testbench文件，或者没有编辑输入变量的值 testbench里是元件申明和映射
Binding Indication error at freqdetect_top.vhd(19): port "class" in
design entity does not have std_logic_vector type that is specified
for the same generic in the associated component
---在相关的元件里没有当前文件所定义的类型
error at tongbu.vhd(16): can't infer register for signal "gate"
because signal does not hold its outside clock edge
Found clock high time violation at 1000.0 ns on register
"|fcounter|lpm_counter:temp_rtl_0|dffs[4]"
Compiler packed, optimized or synthesized away node "temp[19]".
Ignored vector source file node.
---"temp[19]"被优化掉了
Reduced register "gate~reg0" with stuck data_in port to stuck
GND
Design contains 2 input pin(s) that do not drive logic
Warning: No output dependent on input pin "clk"
Warning: No output dependent on input pin "sign"
------输出信号与输入信号无关，
Found clock high time violation at 16625.0 ns on register
"|impulcomp|gate1"
error at impulcomp.vhd(19): can't implement clock enable condition
specified using binary operator "or"
Association List error at period_counter.vhd(38): actual parameter
assigned to formal parameter "alarm", but formal parameter is not
declared
-------连接表错误，形参"alarm"赋值给实参，形参没定义，可能是形参与实参的位置颠倒了，规定形参在实参之前。
Ignored construct behavier at period_counter.vhd(15) because of
previous errors
－－－－－－－－因为前一个错误而导致的错误
error at period_counter.vhd(38): type of identifier "alarm" does
not agree with its usage as std_logic type
－－－－－－－－"alarm"的定义类型与使用的类型不一致
error at shift_reg.vhd(24): can't synthesize logic for statement
with conditions that test for the edges of multiple
clocks
-------同一进程中含有两个或多个if(edge)条件，（一个进程中之能有一个时钟沿）
resolve multiple constant drivers for net "datain_reg[22]" at
shift_reg.vhd(19)
register for signal "num[0]" because signal does not hold its
outside clock edge
elaborate top-level user hierarchy
resolve multiple constant drivers for net "cs_in" at
led_key.vhd(32)
----------有两个以上赋值语句，不能确定“cs_in”的值，
Ignored node in vector source file. Can't find corresponding node
name "over" in design.
---------------在源文件中找不到对应的节点“over”。
access JTAG chain
无法找到下载链
32 Info: Assuming node "clk" is an undefined clock