ADAU1761 DSP VOLUME CONTROL

inventis Question

May 27, 2010 00:00

Hello,

I'd like to use the Single slew Volume block.

I'd like to change the slew rate.

when I export the project in the param.h I found the following parametrs for the volume

#define MOD_ATTCH2_ALG0_GAIS200ALG4GAINTAR_ADDR 192
#define MOD_ATTCH2_ALG0_GAIS200ALG4GAINTAR_FIXPT 0x00800000
#define MOD_ATTCH2_ALG0_GAIS200ALG4GAINTAR_VALUE SIGMASTUDIOTYPE_FIXPOINT_CONVERT(1)
#define MOD_ATTCH2_ALG0_GAIS200ALG4GAINTAR_TYPE SIGMASTUDIOTYPE_FIXPOINT

#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_ADDR 8190
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_FIXPT 0x007FF259
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_VALUE SIGMASTUDIOTYPE_FIXPOINT_CONVERT(0.999583420126834)
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_TYPE SIGMASTUDIOTYPE_FIXPOINT
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_ADDR 8191
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_FIXPT 0x00000DA6
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_VALUE SIGMASTUDIOTYPE_FIXPOINT_CONVERT(0.000416579873166234)
#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_TYPE SIGMASTUDIOTYPE_FIXPOINT

What is the formula to calculate the MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_FIXPT and MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_FIXPT ?

Audio Signal Processors

volume

SigmaDSP Audio Processors

adau1761

slew

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inventis Reply

May 31, 2010 00:00

Hello again,

Anyone in Analog know the slew formula for the Single slew Volume block ?

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ADIApproved Reply

Jun 3, 2010 00:00

Hi Stefano,

Sorry for the delay. I just transferred to a different office, so I don't have any of my hardware available right now to help support customers. I will have my evaluation boards by Monday.

The relationship between Alpha1 and Alpha0 is:

Alpha1 = 1 - Alpha0

#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA0_FIXPT 0x007FF259
Convert value to decimal : 8385113

#define MOD_ATTCH2_ALG0_GAIS200ALG4ALPHA1_FIXPT 0x00000DA6
Convert value to decimal : 3494

Total = 8385113+3494 = 8388607 = 0x7FFFFF (basically, this is 1 minus 1 LSB)

I beleive that increasing Alpha0 (and decreasing Alpha1) results in a faster slew, however I want to confirm this on hardware. I will post my results here ASAP (once I receive my evaluation board shipment).

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EZAdministrator Reply

Aug 2, 2018 00:00

This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

Thank you,
EZ Admin

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