TAS2557: Question of TAS2557 SDOUT Waveforms

Wayne Chen (Audio AE)

Part Number: TAS2557
Other Parts Discussed in Thread: TAS2770

Hi Sirs,

Would you please assist us to review if the TAS2557's SDOUT for echo reference goes to zero gradually with 16 bits ASI a normal behavior? Should we program the TAS2557's ASI to 32 bits all the way to avoid this problem?

1. TAS2557 ASI Word Length = 16, BCLK = 512kHz, LRCK=8kHz

SDOUT floating - TAS2770 SDOUT goes to zero gradually

SDOUT connected to SOC's SDIN. TAS2770 SDOUT goes to zero gradually

2. TAS2557 ASI Word Length = 32, SDOUT floating. BCLK = 2.822MHz, LRCK=441.kHz, TAS2770 SDOUT goes to zero sharply

SDOUT connected to SOC's SDIN. TAS2770 SDOUT, TAS2770 SDOUT goes to zero sharply

Thank you and Best regards,

Wayne Chen
03/05/2019

over 6 years ago

0 Ivan Salazar over 6 years ago

TI__Guru** 112375 points

Hi Wayne,

Do you know the value of B00_P00_R01? Bit 0 of this register configures the DOUT to Hi-Z when there is no valid data transmitted.
You could try to set this bit to 1 (enable Hi-Z) and also enable buskeeper on B00_P01_R05 Bit 7.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Wayne Chen (Audio AE) over 6 years ago in reply to Ivan Salazar

TI__Genius 15950 points

Thank you Ivan.

Customer's lTAS2557 loos like B00_P00_R01/ B00_P01_R05 are zeros. Can the problem be fixed by writing B00_P01_R05 = 0x80?

sh-3.2# cat /sys/kernel/debug/regmap/registers
00: 00
01: 00
02: 00
03: a0
04: 00
05: 00

Thank you and Best regards,

Wayne Chen
03/05/2019

0 Ivan Salazar over 6 years ago in reply to Wayne Chen (Audio AE)

TI__Guru** 112375 points

Hi Wayne,

Yes, I think this should be fixed by writing:
B00_P00_R01 = 0x01
B00_P01_R05 = 0x80

This will enable tri-state for DOUT and also bus keeper.

Best regards,
Applications Engineer - Low Power Audio & Actuators

0 Ivan Salazar over 6 years ago in reply to Ivan Salazar

TI__Guru** 112375 points

Hi Wayne,

Were you able to test this on customer setup? Is this working fine now?

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Wayne Chen (Audio AE) over 6 years ago in reply to Ivan Salazar

TI__Genius 15950 points

Hi Ivan,

Thanks for your concern. Customer is trying to update I2C registers through Linux driver. We will get you back customer's test result shortly.

Thank you and Best regards,

Wayne Chen
03/14/2019

0 Ivan Salazar over 6 years ago in reply to Wayne Chen (Audio AE)

TI__Guru** 112375 points

Hi Wayne,

Do you have additional information on this? If you consider this could take some time we could close this thread and start another one if customer is still having issues.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Wayne Chen (Audio AE) over 6 years ago in reply to Ivan Salazar

TI__Genius 15950 points

Hi Ivan,

Sorry foe delay. Customer found that the SDOUT waveform problem could be solved by setting the TAS2557 to 32 bit I2S format.
Customer thinks this is a workaround but not root cause, hence we need to keep following this issue.

Thank you and Best regards,

Wayne Chen
03/25/2019

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TAS2557: Question of TAS2557 SDOUT Waveforms