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  • USB4715: Can write to SMbus slave AND use I2S bus?
2020/11/13 09:31:30
robhelvestine
Hello Microchip Team,
 
I'm using the USB4715 and the ADAU1961 audio codec in a USB audio design. On the USB4715 EVM, the USB4715 sets up the audio codec to accept an auxiliary input, and mutes the digital microphones. I can tell this by reading the I2C writes that are done on initialization from hub to codec.
For my application, I need to use the audio codec in a difference way. From AN3135, I see that I can write to the codec initialization buffer in order to do this. Writing to this buffer requires the use of SMB2, which is the SMbus slave bus. This requires Configuration 5.
However, the use of the I2S outputs require Configuration 1 or 6. The configuration is latched upon RESET_N assertion, however, so I don't understand how to start in Configuration 5, write the SMbus registers, then switch to Configuration 1/6 to proceed with the I2S bus. From what I understand, I need to write to the SMbus slave registers upon every power-up / assertion of RESET_N, at which point the Configuration is locked.
Is it possible to do this sequence: Start in Configuration 5, write SMbus registers, Send USB Attach opcode, switch to Configuration 1/6, proceed with the I2S bus and audio codec.
If not, then I'm stuck starting in Configuration 1/6 and using the USB4715 in the default configuration which is not desired.
 
Thanks,
Rob
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