TDM signal capture using xCore multi channel audio EVM

[shaminda]

Hi,

I am trying to get a multi channel TDM signal captured and sent to Matlab data acquisition toolbox. To convert TDM to USB I am trying to us the xCORE-200 multichannel Audio dev board.

I am new to xCORE and would really appreciate if you can point to a good example to get started. The microphone array which emits the TDM signal is in master mode and uses its own internal clock and FS signals. The captured signals are shown in the attached .png file.

Furthermore, how can I find the correct ports and pins which I should use to input the TDM signal.

Thanks in advance for your help.

Best,
Shaminda

[babazaroni]

I don't think it's clear about what you are trying to do.

Do you want to connect the microphone array to the dev board and send audio to the host?

[shaminda]

Yes, The microphone array emits a time division multiplexed signal (7 microphone channels ) as shown in the .png file (contains data, bit clock and frame sync signals). I need to capture the audio using the host.

[babazaroni]

That should be doable. You will have to disable/disconnect the codec on the dev board, then jumper over the tdm signals.

I took a brief look at the dev board schematic. Looks like there are headers on the board that allow disconnecting the tdm signals from the codec. You might not need any software modifications if your array puts out the same format as the dev board codec.

Does the dev board use TDM to talk to the codec? If so, then you might not need any firmware modifications.

If it is using I2S, then you will need to modify the firmware to use TDM, and I believe that is now an option in the audio firmware.

[shaminda]

I think I clearly need to modify the software to receive the TDM format of the mic array. The mic array uses a TI codec chip that uses TI DSP (TDM) format (The lines; bit clock, FS and data. Frame sync is followed by a multi channel data stream as shown). Does anyone have an idea what software example will give a good head start to receive the given TDM format.

[babazaroni]

Search for I2S_MODE_TDM in the usb audio firmware.

http://www.xmos.com/support/software/uac2

Also, XMOS has an array microphone product.

http://www.xmos.com/products/microphones

[shaminda]

Yes, the array microphone product seems very interesting. I have already contacted xMOS sales department to purchase the microphone array. However it is only offered to selected customers at this point and I am waiting for a response. If you are from XMOS can I directly reach out to you do discuss purchasing the microphone array solution. If so please provide me the direct contact details. Mine is myfirstname at gmail. myfirstname = shaminda I will provide you details of the project I am working on currently.

Thanks,
Shaminda

[babazaroni]

I'm not with XMOS. It's frustrating not to be able to get these products when they seem available. If you are working for a company, there may be an XMOS FAE assigned to your region. The FAE seems to have enough pull to get these products to you. How you get in contact with the FAE is a mystery. Somehow, XMOS becomes aware of you and the dialog begins. My FAE has moved to another job and we are waiting for another to be hired for our region. Try contacting the sales representative for your region.

[shaminda]

Thanks for the advice.

[shaminda]

Meanwhile I hope some one from xMOS can provide a concrete example for my requirement.