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DRV2605: EN pin not working as specified in datasheet

Chris Myerchin
Prodigy 20 points
Part Number: DRV2605

I'd previously written in about "4 DRV2605YZFR parts on the same I2C bus?"


We went forward with our design, made a prototype and wrote the firmware. 

Now we are finding that the EN pin being low does not prevent writes to the I2C registers.  However, the datasheet writes this should not be the case:

"7.4.1.3 Operation With EN Control"
   "The EN pin must be high to write I2C device registers."

Here is snap shot where where 2 parts a programmed with separate haptic sequences and the 2 enable lines should ensure separate programming.

However, we are finding that all haptic parts always execute the last haptic sequence written out, regardless of what the parts EN pin state was at the time of programming.

Are there any possible software solutions that can save this design?

  • 0
    TI__Mastermind 19245 points

    Hi Chris, 

    I do recall your previous post, I am sorry that the implementation you have developed is not working as expected. this sounds very frustrating 

    I just tested this on an EVM and it I am seeing the same results as you. 

    I talked with a few collogues and we believe that the data sheet is intended to discourage I2C writes when the EN pin is low. 

    On possible solution is to use the GPIO that you have programmed to pull the I2C SCL low to disable I2C communication for a device, 

    this will disable the I2C on any device by removing its clock. the exact values of the resistance may need to be tuned to ensure that when many devices are pulling the bus low through a 22k resistor that the "high" voltage on the I2C bus does not drop too much, and the additional series resistance may affect the rise time on the clock, So the Speed of the bus may need to be decreased, 

    Regards,

    Arthur