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jaws75
 Post subject: Audio problem with I2C and WM8731 codec
PostPosted: Mon Jan 09, 2012 11:57 pm 
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Joined: Sat Dec 31, 2011 5:14 pm
Posts: 1
Hi all,
I am working on a custom board based on AT91SAM9G20 to make working th audio section.
The hardware is like the EVB, connecting Wolfson WM8731 to SSC and I2C bus.
I was able to play something, but it doesn't work 100% of the times.
I see some error on I2C bus:
Code:
i2c-adapter i2c-0: wrote 2 bytes
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: i2c_outb: 0x10 A
i2c-adapter i2c-0: i2c_outb: 0x23 A
i2c-adapter i2c-0: wrote 2 bytes
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: i2c_outb: 0x0e A
i2c-adapter i2c-0: i2c_outb: 0x42 A
i2c-adapter i2c-0: wrote 2 bytes
atmel_ssc_hw_params: RCMR=00010721 RFMR=0000008f TCMR=00010702 TFMR=0000008f
atmel_ssc_dai: Starting clock
atmel_ssc_dai,hw_params: SSC initialized
WM8731 I2C Codec 0-001b: wm8731_pcm_prepare
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: i2c_outb: 0x12 A
i2c-adapter i2c-0: i2c_outb: 0x01 A
i2c-adapter i2c-0: wrote 2 bytes
transmit enabled SSC_SR=0x000104cf
at91sam9g20ek_set_bias_level : level= 1 mclk_on=0
WM8731 I2C Codec 0-001b: wm8731_set_bias_level
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: Used 3 tries to write to client at 0x1b: success
i2c-adapter i2c-0: i2c_outb: 0x0c NA
i2c-adapter i2c-0: sendbytes: NAK bailout.
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: NAK from device addr 0x1b msg #0
at91sam9g20ek_set_bias_level : level= 0 mclk_on=1
WM8731 I2C Codec 0-001b: wm8731_set_bias_level
WM8731 I2C Codec 0-001b: wm8731_mute: 0
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: Used 2 tries to write to client at 0x1b: success
i2c-adapter i2c-0: i2c_outb: 0x0a A
i2c-adapter i2c-0: i2c_outb: 0x00 A
i2c-adapter i2c-0: wrote 2 bytes
ALSA sound/core/pcm_lib.c:1641: playback write error (DMA or IRQ trouble?)
WM8731 I2C Codec 0-001b: wm8731_mute: 1
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: i2c_outb: 0x0a A
i2c-adapter i2c-0: i2c_outb: 0x08 NA
i2c-adapter i2c-0: sendbytes: NAK bailout.
atmel_ssc_shutdown: transmit disabled SSC_SR=0x000000c0
atmel_ssc_dau: Stopping clock
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: i2c_outb: 0x12 NA
i2c-adapter i2c-0: sendbytes: NAK bailout.
pop wq checking: Playback status: inactive waiting: yes
at91sam9g20ek_set_bias_level : level= 1 mclk_on=1
WM8731 I2C Codec 0-001b: wm8731_set_bias_level
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 A
i2c-adapter i2c-0: Used 2 tries to write to client at 0x1b: success
i2c-adapter i2c-0: i2c_outb: 0x0c A
i2c-adapter i2c-0: i2c_outb: 0x57 NA
i2c-adapter i2c-0: sendbytes: NAK bailout.
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: NAK from device addr 0x1b msg #0
at91sam9g20ek_set_bias_level : level= 2 mclk_on=1
WM8731 I2C Codec 0-001b: wm8731_set_bias_level
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: NAK from device addr 0x1b msg #0
atmel_ssc_startup: SSC_SR=0x192
asoc: WM8731 <-> atmel-ssc0 info:
asoc: rate mask 0x6fe
asoc: min ch 1 max ch 2
asoc: min rate 8000 max rate 96000
i2c-adapter i2c-0: master_xfer[0] W, addr=0x1b, len=2
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: i2c_outb: 0x36 NA
i2c-adapter i2c-0: NAK from device addr 0x1b msg #0


Lots of NAK are reported by codec. Once it reach this state any command sent will be replied with a NAK, so the only solution is to power on/off the board and restart the configuration.
The kernel is 2.6.30.

I tested also the new EVB AT91SAM9x5ek that use the same codec and a new kernel 2.6.39.
The audio is very bad and to have the audio working you must switch the master volume to unmute/mute.
A noise is in any case present.

Has anyone been able to get the audio section properly working?

On at91sam9g45ek EVB using another codec with AC97 everything works.

After this analisys I think that we can focus on the issue related to i2c communication between the micro and the codec through i2c.

Any comments or help is welcome.
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jacakk
 Post subject: Re: Audio problem with I2C and WM8731 codec
PostPosted: Mon Jan 23, 2012 10:40 pm 
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Joined: Mon Jan 23, 2012 6:43 pm
Posts: 7
Did you manage to solve NAK errors?
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jaws
 Post subject: Re: Audio problem with I2C and WM8731 codec
PostPosted: Tue Jan 24, 2012 7:23 pm 
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Joined: Fri Jun 22, 2007 10:41 am
Posts: 10
I solved the issue increasing the pull-up resistor on the line. I had previously two 10K pullup.
On the i2C I have attacched an EEPROM and the audio codec.
Now seems work 95% of the time even if I saw some delay between SDA and SCL singnal and the NAK error.
I don't see at all the issue on the EVB, so I think it depends on the line impedence. I want to try to add a serial restor 33ohm on the line near the audio codec and near the eeprom to reduce cross-talk effects.

Hope it helps
Jaws
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jacakk
 Post subject: Re: Audio problem with I2C and WM8731 codec
PostPosted: Tue Jan 24, 2012 11:56 pm 
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Joined: Mon Jan 23, 2012 6:43 pm
Posts: 7
So it seems like it's hardware issue rather than software... I will think about it, thanks anyway :)
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jacakk
 Post subject: Re: Audio problem with I2C and WM8731 codec
PostPosted: Mon Jan 30, 2012 5:54 pm 
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Joined: Mon Jan 23, 2012 6:43 pm
Posts: 7
It's working!
Putting one pull-up resistor (10k) on SDIN line and one pull-up resistor (also 10k) on SCLK line was the solution!
Thanks for help! :)
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