Hardware Sample Rate vs Software Sample Rate
I am confused and am looking for more explanation about the difference between the hardware and software sample rates. Do they have to match? Can your hardware rate be higher than your software rate? Does changing the hardware rate affect calculated filters in your software?
(My specific application I have an ADAU1442).
Thanks in advance for any input.
-Andrew
Audio Signal Processors
filter
adau1442
sigmastudio
SigmaDSP Audio Processors
sample
SigmaDSP
sample_rate
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Hello Andrew,
The hardware sample rate (set by MCLK, the PLL pins, and the core control register) and the software sample rate (atop the schematic in SigmaStudio) should match -- otherwise, as you suspected, any time-related parameters deviate accordingly. This directly affects filter cutoff frequencies, tone frequencies, etc. When a block is added to a schematic, it takes on the sample rate setting then in effect -- which unfortunately allows inadvertently mixing sample rates. This feature is to accommodate designs with several DSPs running at different sample rates. However, within a given processor, all blocks should have the same sample rate. Either set it before adding any blocks, or use the button to the left of the sample rate window to force all blocks to the present sample rate. SigmaDSPs at least up to the Sigma 200 (ADAU1442 series) do not support any mixed sample rate processing.
More info is available at https://ez.analog.com/docs/DOC-1431
Best regards,
Bob
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