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  • USB4715EVM: How to get the digital microphones working
2020/11/13 15:10:45
robhelvestine
Hello.
 
I'm working with the USB4715EVM and messing around with the Configuration registers using the MPLAB Connect tool. 
 
By default, the digital mics are not enabled. I know this by sniffing the I2C writes from the hub to the codec and seeing that codec ADAU1961 address 0x4019 is being written as 0x13, which sets bit INSEL to zero. Also address 0x4008 is not written to, leaving JDFUNC as 0, when it should be 2.
 
I have changed these register values so that INSEL = 1 and JDFUNC = 2. I'm still not getting any audio input on my PC. Is there anything I need to do for the USB4715 to get input audio to work? I understand this question has a lot to do with the Analog device, but considering Microchip's EVM contains this part and the digital mics, I thought I would ask.
 
Thanks,
Rob
2020/12/13 09:35:57
roundrocktom
Did you ever get an answer to your question?
 
I was looking at this and scratched my head with "why on earth is there an audio codec on a USB Hub board".
Then I realized it made sense to have a speaker/microphone for a lot of applications from home office to automotive.
 
AN2001 is the app note that covers USB to the IO functionality.
USB to UART Bridging with Microchip USB 2.0 Hubs   
http://ww1.microchip.com/downloads/en/Appnotes/00002001A.pdf
 
AN2430 was written to cover later devices, like the USB4715
http://ww1.microchip.com/downloads/en/Appnotes/AN2430-USB-to-SPI-Bridging-with-Microchip-USB471x-and-USB49xx-Hubs-00002430C.pdf
 
I don't see any sample code for using that ADAU1961 under the EVM.  I suspect an automotive customer asked for that part to be on the board was the EVM was built but does seem odd to see that codec on USB HUb board, but a neat application for a WFH solution.
 
 
 
 
2020/12/14 06:22:03
robhelvestine
Thanks roundrocktom.
 
I technically didn't get an answer to this question, but don't need one either. We're using analog mics, and I got that working on the EVM. We're using this part on a USB Audio product. 
 
-Rob
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