PCM2903C: How to stream analog input audio source to USB port when power up and initialization finished

user5927389

Part Number: PCM2903C

Hi, all.

I want to implement a function.

When power up the and finished initialization of PCM2903C，then ,the chip defaults to output audio stream to USB port. The audio stream is input from the PCM2903C‘s analog input pins. The USB port is connected to another USB audio player.

over 6 years ago

0 user5927389 over 6 years ago

Prodigy 60 points

I noticed from the datasheet, it should be set by a SET_INTERFACE command on the USB bus before. But what the command is? Is there a easy way to change the default interface? Because the PCM2903C's USB port is connected to a USB audio player ,it is a device not a host ,it can not sent a SET_INTERFACE command really.

0 Ravi Patil over 6 years ago in reply to user5927389

TI__Expert 5645 points

Hi,
The PCM2903C is a USB controlled device. The PCM2903C is a codec, so it has analog input (that goes to an A/D converter) and analog output (that comes from a D/A converter), alongside of the digital path that goes to USB and S/PDIF.

The control end-point is a default end-point and it is used to control all functions of the PCM2903C by the standard USB request and an USB audio class specific request from the host. So PCM2903C can only recieve the SET_INTERFACE command and not generate it...it will always expect the USB request to come from the host.

Best regards,
Ravi

0 user5927389 over 6 years ago in reply to Ravi Patil

Prodigy 60 points

Thanks ,Ravi.

Is there a reference AN document which demonstrate the SET_INTERFACE command using?

0 Ravi Patil over 6 years ago in reply to user5927389

TI__Expert 5645 points

Hi,

Unfortunately we do not have any app note for this. I'll look around to see if we have any examples and will share the same if I do find any. Thanks.

Best regards,

Ravi

0 user5927389 over 6 years ago in reply to Ravi Patil

Prodigy 60 points

Thanks.

So, may be this chip do not adapt our application.

Without USB host,two USB devices can not communicate with each other.

0 Andy Peters over 6 years ago in reply to user5927389

Genius 3945 points

"Without USB host,two USB devices can not communicate with each other."

uhh, because that is how USB works. Two devices cannot communicate with each other.

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PCM2903C: How to stream analog input audio source to USB port when power up and initialization finished