USB Audio input is not working on EK-TM4C1294XL board.

Hello Amit,

Actually, I'm now testing it using 3 different USB audio cards(the below picture is the one of them), but all of the 3 USB cards show the same problem, so I suspect it was caused by the sample application.   I don't have any USB protocol analyzer, but I guess the USB audio cards were streaming the audio data into TC4C1294XL boards because the USB audio cards were working with the Windows PC. 

So, can you please look at the sample application if there's any missing steps or something else? 

BTW, when I searched the USB protocol analyzer, almost analyer are working on Windows system, so is ther any analyzer working on the TM4C1294XL board?

Thanks & B. Regards,

Inbae  

Hello Amit,

Yes, the audio stream is successfully sent from the TM4C to my USB audio devices, thus, the problem is only occurred for streaming from USB Audio device to TM4C. 

Regarding to the USB certified devices or not, I'm not sure if it's certified or not, but I saw the USB certification mark on the device box.

At this point, audio out(TM4C to USB device) is working fine, but the audio in(USB device to TM4C) is not working with the same configuration, so I have searched some documents to find out if there's any additional steps for audio input, but couldn't find it, so do you have any idea for it ? 

Thanks & B. Regards,

Inbae

Hello Amit,

I'm now testing 3 different USB audio cards that were manufactured and selling in Korean market like the below pictures, but all the USB cards shows the same problem (audio playback is working well, but audio capture is not working as I raised this issue. ).   Today, I ordered another USB audio card which has the USB certification, so I'll test it using the device and let you know the testing result again.  

BTW, is the audio capture working with your USB device on 1294XL board?

Thanks & B. Regards,

Inbae

Hello Amit,

Today, I've got another USB audio card that has the USB certification, but the result is the same as before ( Audio playing is working, but capturing is not working. ).

So, I think that it's not the USB compatibility issue because the 4 different USB audio cards shows the same behavior, so I guess that it's caused by some problem in the USB host audio application interface or pin out configuration on 1294XL board, etc...  

I think the usb host audio input has not been tested on TM4C 1294XL board because the 1294XL board doesn't have the usb audio sample applications, isn't it right?, if yes, please test it on the TM4C1294XL board with any USB audio card.

Thanks & B. Regards,

Inbae

Hello Amit,

Do you have any update on this issue?

Any comment would be appreciated.

Thanks & B. Regards,

Inbae

Hello Amit,

Have you had any chances for debugging it?

Any comments would be appreciated.

Thanks & B. Regards,

Inbae

Hello Amit,

Any clue on this issue?

Any comment will be appreciated.

Thanks & B. Regards,

Inbae

Hi Amit,

Thanks a lot for the information, I have verified that the audio capture callback is called continuously with your suggestion.

But, let me ask a quick question, your suggestion is changing the capturing format to Mono from Stereo, 

so does it mean that it's a bug on USB audio driver on 1294XL board? ( The USB host audio in sample application was also provided for the Stereo format. )

Anyway, based on your suggestion, I'll try to capture the Mono audio on 1294XL board and try to play it on the same device with also Mono format, and get back to you if I have any problem for playing it with Mono on USB audio.

Thanks again for the information.

Thanks & B. Regards,

Inbae

Hello Amit,

Let me ask some more questions.

The current status is :
1. The usb_host_audio_input application is working well with Mono.
2. The usb_host_audio_output application is working well with Stereo. (In case of output, only the stereo is working, Mono is not working, but it's not a problem in our project.)

What we want to implement with USB audio :
1. We want to implement a loop-back audio functionality. I mean that I want to play the audio data in real time that are captured from USB audio input.
2. Thus, I made a sample application like this :
Main task initializes the USB audio and creates two tasks, one is for capturing USB audio input data, the other one is for playing the captured audio data to USB output.
3. For this app, my expectations were :
   3.1. The input callback will be called with USB_EVENT_RX_AVAILABLE whenever there're enough captured data in USB input buffer
   3.2. The output callback will be called with USB_EVENT_TX_COMPLETE whenever there're enough available buffer space on the USB output buffer.
4. But, the real behavior on the board was :
4.1. The input callback seems to be called with USB_EVENT_RX_AVAILABLE whenever there're enough captured data in USB input buffer.
4.2. But, the output callback was called with USB_EVENT_RX_AVAILABLE(rather than USB_EVENT_TX_COMPLETE), so I think it's wrong and cannot play it.

Thus, my questions are :
1. Can the USBSoundBufferIn() and USBSoundBufferOut() be called simultaneously in one application?
2. If I want to implement the loop-back audio functionality, is there any guide lines for how to implement it?

Any comment would be appreciate.

Thanks & B. Regards,
Inbae

Hello Amit,

When I searched the documents, there's no comments about the simultaneous calling of USBSoundBufferIn/USBSoundBufferOut.
Thus, can you please let me know how to do it?

Thanks & B. Regards,
Inbae

Hello Amit,

The example code given in TivaWare for usb_host_audio_in does NOT show the simultaneouls calling of USBSoundBufferIn and USBSoundBuffferOut,
it just captures audio data from USB audio input using USBSoundBufferIn(), and it plays the captured data into the speaker on the board using NON USB AUDIO API.

So, let me explain the issue again, I want to implement the USB audio LOOPBACK functionality, it means that plays audio data into USB AUDIO OUTPUT while capturing the audio data from USB AUDIO INPUT, so I created two tasks, one task is capturing audio data from USB audio input using USBSoundBufferIn(), the other task is playing the data into USB audio output using USBSoundBufferOut(), but, in this case, the USB audio input/output callbacks are working as follow :
1. The input callback is ivoked with USB_EVENT_RX_AVAILABLE whenever there're enough captured data in USB input buffer. it's good.
2. But, the output callback was called also with USB_EVENT_RX_AVAILABLE(rather than USB_EVENT_TX_COMPLETE), it's not good, the output callback should be called with USB_EVENT_TX_COMPLETE.

So, I guess that it's a bug in USB audio driver on 1294XL board, or USBSoundBufferIn and USBSoundBufferOut cannot be called simultaneously in one program, or the simultaneouse calling requires some additional procedures, etc..

So, can you please let me know how can I implement the USB audio loopback functinality?

Thanks & B. Regards,
Inbae

The USB bus is a highly complex matter - just download and read the specs. Experts with extensive knowledge are not very widespread. And for performance and resource reasons, this expertise is not primarily sought in the fields the Cortex M devices usually cover. And your question is highly specific. I a person in the know were present, he would probably have answered already.

, does it mean that I cannot get any further help on this issue from this forum?

Most likely, yes.

But perhaps, Tsuneo Chinzei shows up here, to save your day ...

Hello Amit,

Please find the attached sample application for EK-TM4C1294XL, the application is simplified as much as I can just for showing the problem.
It creates two tasks, RenderTask is for playing audio to USB, CaptureTask is for capturing audio from USB.

If you run it on the EK-TM4C1294XL, you can see only the "USBAudioInCallback() was invoked with 2 !!" messages because the USBAudioOutCallback() was called with "USB_EVENT_RX_AVAILABLE", so the USBAudioOutCallback() logs are not printed out.

If you have any questions for the app, please let me know anytime.

Usb_Audio_For_FreeRTOS.zip

Thanks & B. Regards,
Inbae

Hello Amit,

Thanks so much for the fix, finally, it's working now.

Even though USB input is working only for mono whereas output is working only for stereo on 1294XL board, I can hear very clear audio with converting mono to stereo.

Thanks again for the fix.

Best Regards,
Inbae