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TSC2007: About I2C unstable at Fast Mode

Hide
Guru 21045 points

Part Number: TSC2007

Hi Team,

 

If SCL is 400kHz, the operation of TSC2007 is unstable.

(Sometimes I can access TSC2007, and sometimes can’ t access by I2C.)

When access error occurs, SDA (Not SCL) sticks to Low.

 

Could you please let us know if you have any concern and workaround?

 

Regards,

Hide

  • 0
    TI__Guru**** 182821 points

    Hello Hide!

    I am not aware of any TSC2007 issues running at 400kHz.  Can you please describe under what conditions you have a problem with SDA?

  • 0 in reply to Tom Hendrick
    Guru 21045 points

    Hi Team,

     

    Our customer use Linux driver.

    If they touch the screen, processes data in the following order:

    1. PENIRQ Start-up

    2. PENIRQ Invalid and ADC ON, Y measurement

    3. X measurement

    4. Z1 measurement

    5. Z2 measurement

    6. Power Down and PENIRQ Valid

    7. While they touch the screen, repeat "2" from “1”

     

    I have two questions.

     

    [Q1]

    If they remove “6”, an access error don’t occur, so SDA don’t stick to Low.

    Could you please let us know this reason and if you have any concern for this processes？

     

    [Q2]

    When they touch screen by rather light pressure, reads a resistance level of Y is zero unintentionally.

    Even if they set MAV file by Setup command, this phenomenon occurs.

    Could you please let us know this reason and workaround?

     

    If let me know your e-mail address, I can send Source code of the driver included in the Linux kernel source.

     

    Regards,

    Hide

  • 0 in reply to Hide
    TI__Guru**** 182821 points

    Hello Hide,

    Do you by chance have screen shots showing the SDA behavior?

  • 0 in reply to Tom Hendrick
    Guru 21045 points

    Hi Tom-san,

     

    I’m sorry for the delay in my reply.

    We obtained the waveform of SDA from our customer.

     

    If let me know your e-mail address, I can send this waveform.

    I’d greatly appreciate your verification.

     

    Regards,

    Hide