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Explorer
Explorer
6,724 Views
Registered: ‎01-30-2011

unexpected error in FIR core

 sir, i have used xilinx 12.3 fir logicore, but during generation  the ip is not generated. the snapshot is below ihavee also attched the .coe file. plz help me.

wrong bit.jpg

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11 Replies
Xilinx Employee
Xilinx Employee
6,722 Views
Registered: ‎08-02-2011

Re: unexpected error in FIR core

Since you're using radix 16, try specifying the same number of bits for each coefficient. For example, if you're using 16 bit coefficients put '0000' rather than '0' in your .coe.

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Explorer
Explorer
6,718 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core


@bwiec wrote:

Since you're using radix 16, try specifying the same number of bits for each coefficient. For example, if you're using 16 bit coefficients put '0000' rather than '0' in your .coe.


thank you sir, it works. But now there is another problem,if i want  set min freq = 50 db,and max = 100 db, i change the passband and stopband, but it gives, 42.36 db and 43.25 db. plz help me assigning the proper freq range.

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Xilinx Employee
Xilinx Employee
6,713 Views
Registered: ‎08-02-2011

Re: unexpected error in FIR core

From DS534:

 

"The user can specify any range for the passband or stopband, allowing closer analysis of any region of the response.
For example, examination of the transition region can be done to more accurately examine the filter roll-off."

 

Further:

 

"Passband Range: Two fields are available to specify the passband range, the left-most being the minimum
value and the right-most the maximum value. The values are specified in the same units as on the graph x-axis
(for example, normalized to pi radians per second). For the specified range the passband maximum, minimum
and ripple values are calculated and displayed (in dB)."

 

I am not sure exactly what your setup is, or what you're trying to do. Can you provide more details? Maybe a screenshot?

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Explorer
Explorer
6,710 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core


@bwiec wrote:

From DS534:

 

"The user can specify any range for the passband or stopband, allowing closer analysis of any region of the response.
For example, examination of the transition region can be done to more accurately examine the filter roll-off."

 

Further:

 

"Passband Range: Two fields are available to specify the passband range, the left-most being the minimum
value and the right-most the maximum value. The values are specified in the same units as on the graph x-axis
(for example, normalized to pi radians per second). For the specified range the passband maximum, minimum
and ripple values are calculated and displayed (in dB)."

 

I am not sure exactly what your setup is, or what you're trying to do. Can you provide more details? Maybe a screenshot?


sir, i f i want to set the min freq = 50 db and max fre = 100 db, then what will be my passband and stopband range. plz give one example. i am giving the snapshot below. plz also tell me what specification i should change sir ?

 

untitled.JPG

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Explorer
Explorer
6,707 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core

untitled.JPG

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Xilinx Employee
Xilinx Employee
6,706 Views
Registered: ‎08-02-2011

Re: unexpected error in FIR core

Hello,

 

I want to make sure you understand that the coefficients are what specify the filter, not the little analysis pane that you are playing with. Changing things in the analysis pane will not affect your filter.

 

Further, you aren't setting your min frequency. The analyzer is showing you the minimum value of the filter's magnitude response (in dB) in the specified range.

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Explorer
Explorer
6,699 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core


@bwiec wrote:

Hello,

 

I want to make sure you understand that the coefficients are what specify the filter, not the little analysis pane that you are playing with. Changing things in the analysis pane will not affect your filter.

 

Further, you aren't setting your min frequency. The analyzer is showing you the minimum value of the filter's magnitude response (in dB) in the specified range.


sir, i have understood. but my query is, how will i set the min freq to 50 db. actually i want to create some mel filter bank, where different min and max frequency are to be set.i don;t understand wheather i have to change my input sampling frequency or not. the coeficients i enterd,are the coefficients of Bartlett window. my motto is desifn fir filter with bartlett window in different min and max frequncy. i think now, i clearly have said my doubt. plz help

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Teacher rcingham
Teacher
6,693 Views
Registered: ‎09-09-2010

Re: unexpected error in FIR core

"how will i set the min freq to 50 db."

Frequency is measured in Hz, not dB.

------------------------------------------
"If it don't work in simulation, it won't work on the board."
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Explorer
Explorer
6,685 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core


@rcingham wrote:
"how will i set the min freq to 50 db."

Frequency is measured in Hz, not dB.

sorry sir............. ihave mistaken it unmindfully......................now sir can u please give me hints that how can i specify the min and max freq ranges in firlogicore while creating it.

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Explorer
Explorer
2,934 Views
Registered: ‎01-30-2011

Re: unexpected error in FIR core

sir, i have generated a bandpass filter to get the coefficients im MATLAB, and fetch the .coe file in logicore fir compiler, but as i change the passband & stopband frequency in matlab,thegenerated new .coe file with updated coefficients,the db scale shown in the fir compiler frequency response curve,was changed from 50 db to 52.3 db,and 102 db to 102.36 db.even if i increse the stopband and passband freq,it was not changed more. please help.......

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Xilinx Employee
Xilinx Employee
2,929 Views
Registered: ‎08-02-2011

Re: unexpected error in FIR core

You need to think of changing the passband/stopband range almost like zooming in on sections of the filter's response and re-calculating the max/min values based on that.

 

For example, if your passband range already encapsulates the maximum value of the frequency response, widening it won't change the value that is reported in the 'maximum' box.

 

I'm also not totally convinced you understand that changing those values will not change your filter response. It's just an analysis tool.

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