Just wondering if there was an inherent limit to the number of biquad filters you can use in one design, beyond just system memory and number of instructions.
Not that I am aware of. why the question? Is there anything that you have in mind that you think might not work?
Just an incongruity I was coming up against yesterday, it seems to have gone away. I asked because we had some strange results with the TAS3108, where once a certain number of biquads was reached, the dsp would refuse to output anything, and also exceeding 50% of the chip capacity in code words caused strange phase distortion.
Thankfully it seems to be ok again on this chip.
Thanks for the reply.
An update: Using the TAS3204, when I do a build that has over 2030 DSP Code(words) (65.65%) according to the resources window, I get no output.
I did a check with this, when I remove a single component and bring it down to 2027, I get throughput. That includes just running input to output, as soon as it hits over 65.5% or so, it fails.
Is there an error in the resources reporting? Does the chip simply fail to output if you go over the maximum code words? All the other resources are under 60%, except for micro program but that's always around 89%.
Sorry for the delayed response. The message hit my mailbox when I was on vacation, but when I went through my mail when I came back, I missed this one.
Yes, that is somehow a known issue. When the cycle count >2000, then the DSP overran. It was a surprise when it appeared to me the first time. I think the reason is that since TAS3204 has analog in/out and it was oversampled when converting to digital, the up/down sampling took some cycles on the DSP, but when they do the resource calculation, they forgot to take that into account, only calculated what's in the process flow.
I hope this answered your doubt.
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