adau1787 48KHz And 16KHz
Hi All
In my project I have two sources working at different frequencies. The first one works at 48khz and the second one works at 16khz. Both are mainto the adau1787 which is subordinate. The type is standard i2s stereo .
Reading the datasheet it would seem that the serial port can handle these freqencies as well as the asrc. However, if I go inside sigmastudio I find no option to set the 16KHz.
I quote from the text
"ASRCs The ADAU1787 includes ASRCs to enable asynchronous fullduplex operation of the serial ports. Four channels of ASRC are available for the digital outputs, and four channels of ASRC are available for the digital input signals. The ASRCs can convert serial output data from the internal rate of up to 192 kHz back down to less than 8 kHz. All intermediate frequencies and ratios are also supported."
Thank you in advance for your help
Kind Regards
Thread Notes
Alkaline_ot - Moved from SigmaDSP Processors & SigmaStudio Dev. Tool to Audio. Post date updated from Wednesday, April 23, 2025 1:20 PM UTC to Wednesday, April 23, 2025 2:41 PM UTC to reflect the move.
Alkaline_ot - Moved from SigmaDSP Processors & SigmaStudio Dev. Tool to Audio. Post date updated from Wednesday, April 23, 2025 2:41 PM UTC to Wednesday, April 23, 2025 2:41 PM UTC to reflect the move.
software
ADAU1787
Integrated/Special Purpose A/D Converters
Audio CODECs
Hello Alkaline_ot,
You have two sources as master, one at 48KHz and another at 16KHz. I assume your project sample rate is 48KHz, so you would need to convert your 16KHz input to the core rate which is 48KHz right?
Below is the ASRC register, if your project sample rate is 48KHz, then you should select the ASRC out rate to be 48KHz, and then which input serial port SAI0/SAI1 and which channels.
Also note that, your MCLK to the DSP should be synchronous to your input clock sources. If I2S clock sources use different MCLK and your DSP runs on its own MCLK, then you would also need to route your 48KHz input thru the ASRC. It all depends on your clocking system. please let us know how it's done. A block diagram would be helpful.
This is just a basic info, if you want to know more about routings or other project details, then give us some more info.
Do let me know if I misunderstood your question.
Regards,
Harish
Hello Harish
Thanks for reply.
My architecture in this case is as follows.
The dsp has its own mcl at 12.288MHz.
The 16KHz device has its own mclk and has to be master
the 48KHz device has its own mclk but can be either master or slave.
I am preparing a small block diagram for you. In the meantime, however, I want to point this out to you. If it's true that I can set the imput to the value of 48kHz, how do I then set it back to 16KHz for the output?
Audio from both devices is bidirectional, so I must have the ability to receive but also be able to send to connected devices.
Kind Regards
Hello Alkaline_ot,
Thanks for the info.
Alkaline_ot said:
The dsp has its own mcl at 12.288MHz.
The 16KHz device has its own mclk and has to be master
the 48KHz device has its own mclk but can be either master or slave.
In this case, you will have to route both of your I2S signal (coming from external domain) thru the input ASRC and to the core.
You will use one serial port for 48KHz input and another serial port for 16KHz input. Let's say you use SAI1 for 16KHz in and out.
The output ASRC's input rate will be from the source channels (internal) and the output ASRC's output rate will be taken from one of the serial ports (SAI0/SAI1). Please take a look at the datasheet below.
Regards,
Harish
Hi Harish
Thanks for the help. i will try it and let you know. I hope to give you feedback by next Monday!
Regards
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