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DS90UB913A-Q1: I2C tunnel DS90UB913 --> DS90UB914 to external EEPROM

Tobias Krannich
Prodigy 10 points
Part Number: DS90UB913A-Q1

Dear E2E forum participants,

I would like to use the components DS90UB913(I2C master) and DS90UB914 (I2C slave) to realize an I2C communication via a twisted pair cable from the I2C master via the I2C slave to an EEPROM.

In addition to I2C communication, other IO signals are also transmitted.

As far as I have read in the AN SNLA222, communication to the external EEPROM (e.g. 0x50) should be possible:

Slave ID --> 0xA0 (0x50<<1) EEPROM I2C address

Slave alias --> 0xA0 (0x50<<1) EEPROM I2C address

I2C Pass Through --> 1 (default)

I2C Pass Through All --> 0 (default)

Could you please confirm whether it should be possible to read and write to the EEPROM as I suspected?

My next question relates to setting the slave ID and the slave alias. As far as I understand it, the registers are volatile and have to be set anew with every power up. Is this correct? Or is there a possibility that the registers are written once, e.g. in production, and then remain fixed and do not have to be rewritten with every power up?

Thank you very much for your support!

Best regards,

Tobias

  • 0
    TI__Mastermind 20760 points

    Hello Tobias,

    You are correct, with the above configuration you will be able to read and write to the EEPROM. This same strategy can also be used for any other I2C devices in the system. Yes, the registers will return to their default values every power up and will need to be rewritten with every power up.

    Regards,
    Darrah

  • 0 in reply to Darrah Merillat
    Prodigy 10 points

    Dear Darrah,

    thank you very much for your quick support!


    Do you have an idea how a solution without writing the configuration during PowerUp could look like?
    - another variant of the DS90UB913/4 devices with permanent  memory?
    - Select a special I2C address for the EEPROM so that the I2C communication is forwarded independently of the slave ID and slave alias?


    Many thanks and best regards,
    Tobias

  • 0 in reply to Tobias Krannich
    TI__Mastermind 20760 points

    Hello Tobias,

    There are no FPD-Link devices that are able to store custom register configurations on power up. For I2C communication, the address and alias will need to be set. We normally recommend all register configurations needed for a particular system to be written in an initialization script that can be sent once all devices are powered. To limit the total number of writes and registers needing configuration, you could set I2C pass through all, which will forward all I2C transactions regardless of the I2C address. This means that the address and alias would not need to be set for the EEPROM, however this will also open I2C communication for all addresses/transactions, which may not be desirable in your system.