Exceeding capabilities of ADAU1781

Hi there,

I am trying to implement DSP schematic with a 9 band double precision optimized EQ. However, whenever I go beyond 7 bands, I observe a distorted output.

I was wondering if there is a way to identify whether I have exceed the processing capabilities with Sigma Studio. Based on the output, from the compiler, it appears fine. However, the resulting audio output is distorted.

Sigma Studio Version 3.9. Build 2, Rev 1220

Analog Devices Compiler for the 3rd generation SigmaDSP core.

Build date = 7/24/2013 at 10:32 PM

## Summary ##

(Note: Estimates are based on a 48 kHz sample rate)

Instructions used:

447 (out of a possible 512 )

Modulo Data RAM used (X Memory):

226 (out of a possible 512 )

Non Modulo Data RAM used (X Memory):

2 (out of a possible 512 )

Parameter RAM used (Y Memory):

157 (out of a possible 512 )

Instance Mips Inst Data Coeff Other

(max)

SPhat1 162 162 90 52

Automatic Volume Control1 123 123 56 49

Stereo Switch 69 69 22 1

Mid EQ1 17 17 50 39 using: Biquad Looping SP

Beginning 17 17 0 1

SafeLoadCode 15 15 0 7

LPF 10 10 7 8 using: Biquad Looping SP

End 6 6 0 0

Input1 4 4 2 0

Add1 3 3 1 0

Output4 2 2 0 0

Output1 2 2 0 0

Output2 2 2 0 0

Output3 2 2 0 0

Subroutines called:

* Biquad Looping SP 111 13 0 0

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Total 545 447 228 157

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(%) 53% 87% 45% 31%

Files written:

program_data.dat - load file for downloading code using ADI loader

hex_program_data.dat - load file for downloading code using microcontroller

ParamAddress.dat - Parameter RAM locations for schematic instances