AD1940: RMS and readout via SPI
Im a student at the Beuth university in Berlin and im working on my final paper for the Bachelor right now.
I have a problem with the AD1940 Sigma DSP, i want to generate an RMS of an audio stream (I2S) with a time interval of 100ms (could be changed if necessary) and then send the result of this operation again every 100ms to an microcontroller with the SPI interface.
Is there any solution how to get this operation done and to read it out with an µC by the SPI interface of the AD1940 or can i only use the operation moduls in the Sigma Studio library. I didnt find any funktion in the Sigma Stuido software that provided my need features.
The goal is to creat a sound level meter with your Sigma DSP and a microcontroller, im programming the DSP with your "EVAL- ADUSB2EBZ" USBi interface.
Thanks for your time and help.
Best regards,
Udo Kehl
ad1940
Audio Signal Processors
SigmaDSP Audio Processors
Hi Udo,
I'm sorry for the late response. I saw your emails in our support system, but I am traveling in Asia on business and it has been difficult for me to keep up with all of the support emails coming in.
In order to read the average level of a signal, refer to this tutorial:
https://ez.analog.com/message/7669#7669
You can use several bandpass filters in front of each of the envelope cells in order to get a reading of the energy in each band.
Use a T connection to feed the same signal into all of the audio bands.
In order to read back from the DSP readback cell, you need to read the section of the datasheet describing the Data Capture registers. That is on page 23 of the datasheet, which you can find here; https://www.analog.com/static/imported-files/data_sheets/AD1940_1941.pdf
You can use the capture window to find exactly which addresses the microcontroller needs to read and write in order to get this information: http://videos.analog.com/video/applications/automotive/756712926001/SigmaStudio-C2-Capture-Window/
There is an example showing how to generate some files that help with microcontroller development here: https://ez.analog.com/docs/DOC-1806
I hope this is enough to help you.
Best Regards,
Brett
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