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drv2605l not responsive to I2C commands after system comes out of standby

Rudy Garcia
Intellectual 380 points
Other Parts Discussed in Thread: DRV2605L

Hi,


I have a drv2605l on my board. VDD is connected to my system voltage (~4.2V). The I2C pullup resistors are pulled up using 3.3V which is regulated from my system voltage. There are conditions where my system goes into standby mode. In this mode the 3.3V rail is not active and all the I/O on the board is not powered. In this case the drv2605l only has power present on VDD but all the other signals are not powered. After the system exists standby and returns to the active state the application processor on my board tries to access the drv2605l via the I2C. The drv2605l is not responding (NACK).

Any ideas on what could be happening?

Thanks,

Rudy

  • 0
    TI__Expert 8940 points
    Hi, Rudy:

    I am not quite sure about what is happening.
    I have an idea to test: after the system returns to active state, could it be possible that delay 10 ms before accessing DRV2605L?

    DRV2605L has an I2C Watchdog Timer.
    If an I2C stops unexpectedly, the possibility exists for the I2C protocol to remain in a hanged state. To allow for the recovery of the communication without having to power cycle the device, the DRV2605L device includes an automatic watchdog timer that resets the I2C protocol without user intervention after 4.33 ms.
  • 0
    TI__Genius 12485 points

    Rudy,

    Thanks for getting to us. Could you share:

    1. Schematic around the DRV system?

    2. Oscilloscope plots on the battery and the I2C?

    My suspicion is that when the 3.3 rail is coming up from Hi-Z condition, since the I2Cs are pulled up to that pins, the DRV SCL, SDA pins are seeing that voltage go from 0-3.3V.

    3. What is the status of the EN pin?

    Regards,

    Gautham Ramachandran

    Apps. Engineer - Haptics.