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changlei1990
Visitor
Visitor
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Registered: ‎06-13-2018

The coefficients cannot be reloaded correctly when the interpolation filter(FIR7.2) I selected is more than three times interpolated

I built a project with the FIR7.2 compiler as shown in the figure. It is a four times interpolation filter with a coefficient of 1 2 3 4 5 6 5 4 3 2 1 . The reload_tdata  is 44 45 46 47 48 49 48 47 46 45 44,The input data is 1 0 0 0 0 0 0 0 0 0 0 (9)。As we know, the core is to interpolate the data first, then filter it. After four times interpolation and filtering, I think the output should be 44 45 46 47 48 49 48 47 46 45 44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (19).

The filter output is correct when we do not select the coefficient reload(FIR2). However, when we selected coefficient reload, the output of the filter is obviously incorrect(FIR3). The other configurations of both of them are the same.

 Is my setting incorrect? Who can tell me HOW to do it?

Thank you for your help.aa.pngbb.pngdd.pngss.png

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nathanx
Moderator
Moderator
395 Views
Registered: ‎08-01-2007

The interpolation FIR filter configuration is correct.

As for the reload interface, the RELOAD channel packet length is derived from the number of coefficients specified at core generation time and the filter implementation used. See sections Coefficient Reload and Coefficient Reload Tab on the IP GUI for details on how to generate the content for the channel.

The second thing is the set of data loaded into the RELOAD channel does not take action until triggered by a reconfiguration synchronization event as described in CONFIG Channel, which means after the set of coefs is loaded to reload channel, you need to send a configuration pakcet to CONFIG channel in order to trigger the loaded coefs.

Finally, after the reloaded coefs is triggered, you need to send another data input into the core.

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