PCM3002 Device drivers

Hi, Prashant,

Welcome to E2E, Thanks for your interest in our products!.

I am afraid we don't have any driver available for this device, this is a simple part which configuration only requires the write of a couple registers.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

Thanks for your reply,

i Have gone through the registers, specifically the Register 3 talks about configure the Chip 16-bit MSB-first left-justified, 20-bit MSB-first left-justified, 20-bit MSB-first left-justified and 20-bit MSB-first I2S mode,

can you please help us understand the difference between these modes and 20-bit MSB-first I2S mode means are the left justified modes different than the I2S mode?

secondly the three wire MC,MD,ML interface don't follow any specific protocol, do we need to bit bang them to config the chip for I2S mode?

Third if yes is there any sample source code for the bit bang with TI?

Thanks.

Hello Diego,

We are using the settings for program registers provided in previous reply for I2S mode on Audio Codec PCM3002

We have below observations:

- Dout is generating clock without any input sound file

- Once sound file is played using ALSA drivers, Dout output zero and Vout becomes Vcc/2

- system clock is set to 13.2 MHZ, bit clock is coming around 2.79 MHZ, LRCIN is 48 KHZ for audio file of 48KHz.

Please refer to attached waveform results for audio file with 48 KHZ frequency.

As mentioned in PCM3002/3003 datasheet,  if system clock and LRCIN are not synchronized, then Dout output results in zero and Vout becomes Vcc/2.

We are under impression that our system is going into this mode. Is there any way to confirm this?

If this is not the case, please suggest what could be the cause, for not getting Dout and Vout in normal mode.

Thanks,

Prashant

Hello Diego,

Below are the settings, we are using in Program registers of PCM3002:

Register0: 0x01FF

Register1: 0x03FF

Register2: 0x0442

Register3:0x060C

We are setting up I2S mode format on audio codec. Program registers are being set through bit banging using memory modification tools on connected GPIO's (ML, MC and MD).

Below are the clock settings:

sampling frequency (fs) is 48 KHZ

bit clock is set to 3.072 MHZ (20-bit MSB first I2S format for 2 channels)  <= 32*2*fs

System clock is set to 24.57 MHZ <= 512 *fs

We are getting noise output on Vout pin when audio file is played with above settings.

Below are my questions:

1. Do we have any verification tool to check if program registers are set properly or not?

2. If program registers are set properly (Assuming), what should be the output on Dout and Vout pins?

Thanks,

Prashant.

Hi, Prashant,

Thanks for the feedback. The Clock settings seems fine now, however, I would like to recommend checking the format used by the host processor and codec. I have seen cases where a formar mismatch leads into noise on the analog and digital outputs.

Unfortunately, there is no verification tool available, as mentioned before this is a quite old device which tools and support options are limited. Assuming the registers are properly set, the digital output (Dout) should stream the content recorded on the ADC inputs, having a toggling on the lower bits (noise floor), while the analog output (Vout) should stream the audio provided through the digital input (DIN).  

Do you have some captures of both Dout and Vout with and without providing analog and digital inputs?.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

Please find below details:

Graph 1: Audio play output

Yellow Waveform: Dout

Pink Waveform: Vout

Graph 2: Without Audio play

Above output captured with same settings as mentioned earlier.

Please find attached word document with the procedure, detailed waveform and timing diagrams created while working with PCM3002 interfacing.

Do let me know if any missing step or some other issue(s).

 Audio_Codec.docx

Thanks.

Hi, Prashant,

Thanks for the additional feedback, the steps from the document you shared seems fine for me. The output audio seems definitively strange, I suspect there is a problem between the device expected format and processor's data format. One thing I would like to recommend in order to  move forward and discard a problem with the device is to try using another digital Audio master, if the issue is still there, it is likely that the PCM3002 is not being properly configured. Unfortunately there is not much information abut this part and the way to program it is not very flexible.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

Referring to last waveform shared about Vout and Dout, there has been mistake while tagging those waveform.

Yellow colored waveform indicates Vout output and pink one represents Dout output.

Unfortunately, we do not have another digital audio master to test on. Most probably, program register settings done through bit banging seems to create some issues. As with reset and after setting up program registers, we are getting same results on output pins. Plus, even after enabling Mute, we are receiving output at both the pins Vout and Dout. Document (shared in last reply) provides details about timing diagram while setting up program registers. Please confirm if the actual time frames are in valid ranges or not.

Thanks,

Prashant

Prashant,

After looking at the control interface clock specs,it seems the signals used to configure the part are faster than the expected from the device. I am not sure if this could be an issue, there is not much information about this type of interface, so the only recommendation I can provide is to try changing the configuration signals to make them slower and meet the timing details from the datasheet. The I²S clocks seems fine, but my only question would be to verify if effectively the data starts one bit after the LRCK changes (as should be on I²S format). One other suggestion I have is to set the host processor to operate in left justified mode and operate the PCM3003 in default mode without any configuration.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer