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TUSB8044A: register setting

Kurumi Hasegawa
Expert 6351 points
Part Number: TUSB8044A

Hi team,

 

My customer is considering using TUSB8044A with AM437x, and got questions on register setting method.

Could you please take a look below?

Please note the customer is referring to TUSB8044AEVM design.

[Q1] They might need to change register setting from the default value.

From the TUSB8044AEVM User’s guide, it seems that initial setting for configuration register is done through EEPROM.

However, the customer want not to implement EEPROM on the final design.

Is it possible to change setting by MPU through I2C, without EEPROM?

 

[Q2-a] If the answer for Q1 is Yes, then how can we do that?

Is there any material showing the steps?

 

[Q2-b] If the answer for Q2 is No, then does that mean implementation of EEPROM (like EVM) is necessary?

Could you share how we can change the register setting, when changing it through MPU is impossible?

 

Best regards,

Kurumi

  • 0
    TI__Guru 60865 points

    Hello Kurumi,

    The TUSB8044A can be configured by a SMBUS/I2C host.  If the SMBUSz pin is set low, then the hub will wait to be configured by a SMBUS/I2C host, when configuration is complete, the SMBUS/I2C host will set the cfgactive bit in the hub registers and the hub will be ready to connect.  See sections 8.4.1 and 8.4.4 in the datasheet for more information.  Please note that there are internal pulldowns on the SDA/SCL pins that can impact the system I2C bus signaling levels.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 6351 points

    Hi JMMN,

     

    Thank you so much for your prompt reply.

    I’m not really familiar with SW perspective, so can I confirm below?

     

    • SMBUS/I2C host in this case means AM437x
    • Hub in this case means TUSB8044A
    • It is possible to change resister setting without EEPROM, but by AM437x though I2C

     

    Best regards,

    Kurumi

  • 0 in reply to Kurumi Hasegawa
    TI__Guru 60865 points

    Yes, it should be possible to configure the TUSB8044A with the AM437x.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 6351 points

    Hi JMMN,

    It was mentioned on the datasheet that TUSB8044A can be configured by external I2C EEPROM, or SMBus. In my understanding I2C and SMBus is compatible but not the same. Did you mean TUSB8044A can be configured by SMBus? Or is it possible to access through I2C as well?

    Also, would you be able to explain a bit more on below comments? Did you mean I2C (or SMBus?) bus line connected to the TUSB8044A SDA/SCL might have lower signal level because of internal pulldowns ? 

    JMMN said:
    Please note that there are internal pulldowns on the SDA/SCL pins that can impact the system I2C bus signaling levels.

    Best regards,

    Kurumi

  • +1 in reply to Kurumi Hasegawa
    TI__Guru 60865 points

    It is likely that the AM437x I2C interface will meet the SMBUS host requirements, most controllers do.

     Did you mean I2C (or SMBus?) bus line connected to the TUSB8044A SDA/SCL might have lower signal level because of internal pulldowns ? 

    [JMMN]  Yes, this is correct.  Strong pullups on SDA/SCL are required (1K - 2K)

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 6351 points

    Hi JMMN,

    Thank you so much! I've got few additional questions which might be better to discuss offline. Please allow me to contact you via email.

    Best regards,

    Kurumi

  • 0 in reply to Kurumi Hasegawa
    TI__Guru 60865 points

    Hi Kurumi,

    We can communicate offline using the messaging feature on E2E.  Please accept my friend request.

    Regards,

    JMMN