• State TI Thinks Resolved
  • Locked Locked
  • Replies 30 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 3005 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV320AIC23EVM2: Need support to plot data

Anika Anika
Prodigy 170 points

Part Number: TLV320AIC23EVM2
Other Parts Discussed in Thread: TLV320AIC23B

We are doing a project to demonstrate the effects of quantization. So we are using this device to convert the analog data to digital and then back to analog. Each time when we change the number quantization bits we want to plot the data to understand the difference in waveform due to the quantization bits. So we wanted to know if the digital data is stored somewhere and how to access that file. There is a datalog option but I don't know if that would store the digitized form of the analog signal that we put in. Moreover how to access that file? If it's not possible to access the digital data somehow, how can we plot the different waveforms by changing the number of bits?

Please let us know soon.

Thanks

  • 0
    TI__Mastermind 30240 points
    Hi Anika,

    This is a really old EVM. (2002) it does not store anything on the board, and it does not automatically send data to a computer.
    J7 is the Digital I/O. If you have any means of getting the I2S data from that port to a computer, the process should be quite simple.

    The Generation of Audio codecs directly after this device (the TLV320AIC310x family) had a TAS1020B Audio USB processor that handled that. Is this the only TI codec you have?

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Hello,
    That helps. But can you tell me the exact steps to transfer I2S data to computer? Like what cables do we need? do we need a software to use the data in a computer? Can you tell me the exact process?

    Thank you for your response. Looking forward to your reply.

    Kind Regards
    Anika
  • 0 in reply to Anika Anika
    Prodigy 170 points
    Yes, that the only codec we have. I have another question, the minimum number of quantization bits in this codec is 16 bits, can we change it to 8 bits by any chance?

    Thanks

    Kind Regards
    -Anika
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Anika,

    I'm afraid it's not as simple as using a specific cable. There are processors dedicated to USB audio, like the TAS1020B I mentioned before. That is the device that interfaces with the computer. You might see some very high end Hifi audio cards for PCs that have I2S outputs, but an input is typically not desired.

    -Steve
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Anika,

    That TLV320AIC23B is 16,20,24, or 32Bit. 8 bit is very low resolution for audio, and thus you will not see any modern devices use 8-bit format.

    -steve
  • 0 in reply to Steve-Wilson
    Prodigy 170 points

    Can I use a 3.5mm audio jack to BNC to connect the line out bits from the EVM to oscilloscope and plot the analog signals? In that case we would be able to see the difference in waveform when 16 bits to 32 bits are used. If not how else can we plot waveforms to see the difference?

  • 0 in reply to Anika Anika
    Prodigy 170 points

    We are inputting analog audio signals to the EVM through the line in. Then we can listen to the output signal by connecting a headphone to the line out. We can also modify the sampling frequency and the quantization bits using the software. But right now, we want to plot the different signals from the line out and visually see the difference instead of listening to it. So one idea is to connect it to the oscilloscope with a 3.5mm audio jack to BNC connector. Will that help? Or there are other ways of plotting it?

    Thanks
    -Anika

  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    if you want to use the Analog out, you could hook the 3.5 mm audio jack up to the computer's audio input jack and use Audacity to record the audio. However, it should be noted that the Computer will have its own ADC internally that would color the results.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Thanks Steve, But I want to plot it, can Audacity plot it so that we can visually see the waveform? Or Can I use 3.5mm audio jack to BNC to connect it to the oscilloscope? Which way is better?
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points

    Anika, 

    Audicity will visually display the waveforms.  here is a screenshot of a 5k tone I created.  16-bit, 44.1k

    best regards, 

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Thank you so much Steve. That was a great help. We will have to submit the project in the next two weeks so I will keep posting you questions, if I have any till then.

    My second problem was to use the external clock. As this device has sampling frequency as low as 8khz to go below that we want to use an external clock. So I am connecting the J8 to function generator. What are the other steps I need to go through?
  • 0 in reply to Anika Anika
    Prodigy 170 points
    Another question is I understand the use of Audacity, but to keep a second option can I use 3.5mm audio jack to bnc to connect the evm to the oscilloscope and plot it?

    Thanks
    Anika
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    You could certainly try that too, but make sure that there is not some kind of averaging function on, and you should probably only do a single capture.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Okay, I will try both. But to talk about the external clock, we are connecting J8 to the function generator. Then what should be the steps to continue? And using the external clock can we change the sampling frequency to below 8kHz?

    Thanks
    -Anika
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Anika,

    the External clock will not change the sampling rate. You need to configure the sampling rate control register (see section 3.3.2 of the datasheet) The MCLK should be 12MHz.

    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points

    yeah I know that MCLK is 12MHz and have gone through the sampling rate control registers. The sampling starts from 8kHz, can we change it to smaller value?

  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    You are welcome to experiment with the sampling rate coefficients and MCLK frequency and try. 8khz is the lowest sampling rate that our customers use. so trying to take it lower would be an atypical use case. it is likely possible, and I encourage you to give it a go.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    So if we change the MCLK frequency using the external clock, then it is possible to have a sampling frequency below 8kHz?

    -Anika
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    The design files for this device are archived and any design engineers that worked on this device are long gone, so I can't really make any promises, but it stands to reason that slowing the MCLK could result in a lower Fs. How low are you aiming for?
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    If possible we want it to be 2kHz.
    Thanks
    -Anika
  • 0 in reply to Anika Anika
    Prodigy 170 points

    If I connect the function generator to the EVM, do I need to change any other settings to the software to use the external clock. Please give me the step by step process of using the external clock.

    Thanks

  • 0 in reply to Anika Anika
    Prodigy 170 points

    Hello,

    I am trying use the external clock by connecting the J8 to function generator and have applied sine/square/triangular wave. I have changed the settings in the software from master mode to slave mode. Still I don't here anything when it is in slave mode. When I put this back to master mode it works. But in both cases the clock frequency is not changing, and if changing I can't see it in display of the software. Can you tell me what other settings do I need to change to use the external clock? Please help me in this.

  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points

    Anika, 

    in Master mode, the AIC23b will generate the BCLK, LRCOUT and LRCIN.  In slave mode the AIC23B must have those clocks supplied to it. 

    One thing to note is that the AIC23BEVM2 has a crystal (Y1) which is the default clock.  If you are supplying an external clock, remove Y1, and insert a jumper in JP2.

    Can you confirm you have done this?

    Best regards, 

    -Steve wilson

  • 0 in reply to Steve-Wilson
    TI__Mastermind 30240 points
    one last thing... Y1 is socketed, so you will not need to desolder it.
    -Steve
  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    I have put a jumper at JP2 and there is one jumper at JP1 also. Like you said Y1 cannot be unsoldered so how do I remove Y1? Secondly after putting the jumper in JP2 we can hear different sound in slave mode (I am assuming slave mode is for external clock). But if the clock frequency have changed then it's not displayed on the software.
    One more thing is do you know the exact relationship between clock frequency and sampling frequency?
    Thanks
    -Anika
  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Anika, Y1 is socketed, to remove it just pull it out.

    I regarding the exact relationship between the mclk and the Fsref I do not know, as I've said before, this device is very old, the design files are archived, the design team is long retired. This device will likely be changed from "active" to "NRND" (not recommended for new designs). Thus the support that I am able to provide is very limited.

    best regards,
    -Steve wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points

    Hello, as we have to submit the project next week, I have couple of questions for you.

    1. There is a digital filter in the EVM which is cutting of input signal if it is above half the frequency of the sampling rate. How do we turn that off?

    2. What does "Analog Control Bypass Enable do"?

    3. To use the external clock we are following the steps mentioned below:

    -Remove Y1

    -set jumper at JP2

    -connect function generator at J8

    -change master to slave mode in the software

    Are these steps correct or do we have to do something else?

    4. When we are using the slave mode we assuming the external clock is working, so the sampling frequency should change. In that case where should it display the sampling frequency?

    5. When we are following the above steps to use the external clock we have the following problem:

    -since the external clock is working it should not display the MCLK and Fs from the internal clock previously chosen, but it shows that.

    -even if we do not connect any input to the EVM when the external clock is there, we get to listen to the output and the output is the external clock.

    Please answer questions.

    Thanks

    Anika

  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Anika,

    1. This is integrated into the device, It is not possible to disable.
    2. Where do you see this?
    3. It would probably make sense to turn off the OSC block too. since you aren't using it.
    4. I'm not very familiar with this software, but it certainly doesn't measure the sampling frequency. if it displays a sampling frequency, it will display the frequency it "thinks" the device is set to.
    5. can you clarify ? what shows the MCLK and Fs? what do you mean by "the output is the external clock"?

    -Steve
  • 0 in reply to Steve-Wilson
    Prodigy 170 points

    Hello,

    We actually needed an audio codec that had Fs of 4khz or 2khz and does not block audio signals of frequency above half the sampling frequency. Do you know of any software that can do something like this?

  • 0 in reply to Anika Anika
    TI__Mastermind 30240 points
    Matlab could definitely simulate that.

    Best regards

    -Steve