Linux: LM49352 : Loud Speaker doesn't work after power up and registers setting.

Roger Luo

Prodigy 160 points

Tool/software: Linux

Hi,

We're using LM49352 as an audio codec. The project basic information list as bellows,

Linux Kernel -- 3.14.52

Audio formats -- PCM (slave)

NO MCLK, use PORT1_CLK （2.048MHz）

sampling frequency -- 8kHz

{ 0x00, 0xa9} { 0x01, 0x01} { 0x10, 0x03} { 0x20, 0x10} { 0x21, 0x00}
{ 0x23, 0x0f} { 0x30, 0x11} { 0x31, 0x00} { 0x40, 0x00} { 0x41, 0x00}
{ 0x44, 0x09} { 0x50, 0x27} { 0x54, 0x1b} { 0x55, 0x02} { 0x56, 0x02}
{ 0x15, 0x0c} { 0x16, 0x0f}

I have read the registers and the values are the same as written. It's supposed that loud speaker should be working but actually no voice at all. As data sheet said on page 39, there should be two outputs (LS+ and LS-) switch at 300KHz from VDD to GND with a 50% duty cycle, with both outputs in phase. We don't get 300KHz square wave either. Can you explain this? How can we get the 300KHz square wave? It's related to hardware design or registers settings?

Thanks,

over 5 years ago

0 Steve-Wilson over 5 years ago

TI__Mastermind 30030 points

Roger,

I will take a look at your register configuration and get back to you today.

best regards,
-Steve Wilson

0 Roger Luo over 5 years ago in reply to Steve-Wilson

Prodigy 160 points

Hi Steve,

Thanks for your support and look forward to your reply. And I'd like to know if the clock 2.048MHz can be the source clock to drive ADC or DAC instead of MCLK.

Thanks,

Roger Luo

0 Roger Luo over 5 years ago in reply to Roger Luo

Prodigy 160 points

Hardware design for your reference.

0 Steve-Wilson over 5 years ago in reply to Roger Luo

TI__Mastermind 30030 points

Roger,

Yes, the 2.048Mhz clock should be fine.

Are you able re read back the registers you wrote?

Can you tell me more details about your desired data format?

Seems like you are doing 14 bit PCM? Is that right?

best regards,

Steve Wilson

0 Roger Luo over 5 years ago in reply to Steve-Wilson

Prodigy 160 points

Hi Steve,

Desired data format:

PCM long sync

L-PCM sample foramt

16 bit PCM

Thanks,

Roger Luo

0 Roger Luo over 5 years ago in reply to Roger Luo

Prodigy 160 points

Hi Steve,

Now I got speaker working. But as I measured the frequency of LS+ and LS- and it's 500KHz not 300KHz as datasheet indicated. Can you explain this?

More importantly, I got loud noise from speaker. Can you provide which registers are related to this issue? Brief information about voice channels listed below.

Port1_ RX => DAC => LS

MIC => ADC => Port1_TX

How can I eliminate the noise?

Thanks,

Roger Luo

0 Steve-Wilson over 5 years ago in reply to Roger Luo

TI__Mastermind 30030 points

Hi Roger,

Out of curiosity, what did you change to get the Speaker working? the frequency should be 300khz.

The loud noise could just be a data format mismatch. can you get a screenshot of the I2S CLOCKS and DATA?

best regards,
-STeve Wilson

0 Roger Luo over 5 years ago in reply to Steve-Wilson

Prodigy 160 points

Hi Steve,

It's PMC clock register setting issue. Now I got both speaker and mic working normally on Linux 3.18. Sound is good and life is good. Thanks for your support.

Sincerely,
Roger Luo

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Linux: LM49352 : Loud Speaker doesn't work after power up and registers setting.