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ADAU1701: safeload overhead

SigmaDSP & SigmaStudio SteveL Apr 30, 2012 00:00 2 replies Original on forum ↗
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SteveL Question
Apr 30, 2012 00:00

Hi,

The ADAU1701 datasheet states that each safeload write performed (up to the maximum of five) eats up one core instruction period and that the maximum program length should take this into account. So at 48kHz, the maximum program length should be 1024 - 5 = 1019 instructions if one wants to use all five safeloads simultaneously.

My question is: what happens at faster sample rates? If I am working at double-rate (i.e. 96kHz), where only half the number of core instructions are available, is it still OK to deduct five instructions for the safeloads (i.e. the safeloads take a fixed number of cycles) or must I deduct ten (i.e. the safeloads take a fixed amount of time)?

I really hope it is the former, as I am sailing very close to the wind with my current design and every instruction counts!

Thanks for any guidance,

Steve L.

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SigmaDSP Audio Processors

adau1701

ADIApproved Reply
Apr 30, 2012 00:00

Hi Steve,

This is instruction overhead, not execution time overhead, so 5 cycles should be fine with any sample rate.

Be sure to wait one sample between each safeload operation.

SteveL Reply
May 1, 2012 00:00

Thanks Brett.

Glad to hear it is the lower figure - I need every cycle in my current project.

Best regards,

Steve L.