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TAS5717 I2C problems

Paul White
Prodigy 65 points
Other Parts Discussed in Thread: TAS5717

I am trying to communicate with a TAS5717 using I2C without any luck.  The +3.3v supply seems to be correct and another device (EEPROM) on the same I2C bus is working ok.

The reset and power down pins are both high.  I have tried both addresses 0x54 and 0x56 and the first byte of the I2C message is not ACKed by the 5717. I have looked at the SCL and SDA signals at the chip and they look fine, with a 0 to +3.3V voltage swing.

Is there something I am forgetting?

  • 0
    TI__Guru**** 189399 points

    Hi, Paul,

    That's a little odd. When you say +3.3V, are you powering both AVDD and DVDD?

    It seems like it should be working.

    -d2

  • 0 in reply to Don Dapkus
    Intellectual 605 points

    All,

     

    We have taken an Eval board and wired in the I2C from Paul's PCB to the tas5717 and that works (able to read/write registers).

    Thanks,

    Rinzai Bell

    Avnet TI FAE

  • 0 in reply to Rinzai Bell
    Prodigy 65 points

    I  am powering both DVDD and AVDD (pins 8, 13, 27 are all connected to +3.3V).  The voltage is correct and looks clean.  All VSS pins, analog and digital are grounded.

    I did an experiment where I powered the small evaluation board from our board, with connections from our board only to AVDD, DVDD, GND, SCL and SDA on the eval board.  The communication between our processor and the tas5717 on the eval board worked fine.

    Looking at the data sheet, I read that the max rise time for SCL and SDA is 300ns.  I measured just about 300ns rise time, so I changed the I2C pullup resistors from 4.7K to 2.2K.  The rise time dropped to about 100-150ns, but there was still no communication.

    Is there some difference between the chips we are using and the one on the eval board?  The eval board part is marked:  TAS5717 / 0AT / D2S1.  The part on our board is marked:  TAS5717 / 0C1 / ALX2.

     

     

  • 0 in reply to Paul White
    TI__Mastermind 22965 points

    Hi Paul,

    Thanks for confirming. Can you also please verify that the STEST (pin-26) is connected to GND on your board?

    The current draw of the 3.3V supply (AVDD+DVDD) would be a good datapoint to verify that the device is working normally. If possible can you please measure this on your board (and perhaps also compare when the supply is connected to the EVM)? 

    Also, is this behaviour seen on multiple boards/devices?

     

    Best Regards,

    Ravinder

    Audio Applications Engineer.

  • 0 in reply to Ravi Singh
    Prodigy 65 points

    The STEST pin is connected to ground.

    I can't measure the 3.3V current -- it's a power plane powering several other devices and there's no way to break the circuit just to the tas5717.  I did measure the current on the eval board at about 32mA.

    So far, this is the only prototype board that's been built.  We should be getting more assembled later this week.

  • 0 in reply to Paul White
    Prodigy 65 points

    I found the problem -- the resistor on pin 16 (OSCREG) was the wrong value.  Instead of 18.2K, there was a 220 ohm resistor.  After replacement, the chip is talking!

  • 0 in reply to Paul White
    TI__Guru**** 189399 points

    Paul,

    What's 18k between friends?

    I'm glad you got it talking. Let us know if you need anything else.

    -d2