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DS100BR111: DS100BR111

Kevin Shafer
Prodigy 60 points
Part Number: DS100BR111
Other Parts Discussed in Thread: DS100BR210

Tool/software:

Our intent is to use the device in the SMBus Master Mode (ENSMB = Float) to read in device setup values from an external EEPROM at power-up.  However, section 8.3 SMBus Master Mode in the datasheet states that access to the SMBus lines is not possible if the EPPROM fails to load settings (e.g. blank EEPROM).  If this is the case, how do you perform initial programming of a blank EEPROM on a brand new board assembly?

  • 0
    TI__Mastermind 23765 points

    Hi Kevin,

    Here are some common options I can think of to program the EEPROM.

    • Include series 0 ohm resistors on SDA and SCL lines which can be depopulated to isolate the redriver from the I2C bus. Then another device can program the EEPROM without the redriver assuming master control.
    • Include a pull-up resistor footprint on the ENSMB pin. This can be populated to place the redriver in SMBus slave mode, allowing another device to program the EEPROM.
    • Power on the EEPROM without powering on the redriver. Then another device can program the EEPROM without the redriver assuming master control.
    • Program the EEPROM before installing on the new board.

    Best,

    Lucas

  • +1 in reply to Lucas Wolter
    Prodigy 60 points

    Lucas:

    Thanks for the suggestions.  These are things I did think of; however, except for the last option these are not ideal for production as these require soldering/unsoldering components after EEPROM programming.  Since our initial boards have already been released, I guess we will need to use one of these options during initial bring-up and link tuning.  Once the production EEPROM image is determined and verified, we could consider the last option.  Otherwise, we would need to spin the boards to add features to allow for connection changes without soldering/unsoldering.

    Regards,

    Kevin

  • 0 in reply to Kevin Shafer
    TI__Mastermind 23765 points

    Hi Kevin,

    I understand it will be difficult for you to flash the EEPROMs. Unfortunately I don't see an easier option. In SMBus master mode, the DS100BR210 will assume master control of the I2C bus after power-up. It will fail to load from a blank EEPROM and will indefinitely maintain master control of the I2C bus.

    Best,

    Lucas

  • 0 in reply to Lucas Wolter
    Prodigy 60 points

    Lucas:

    Understood. Thanks for the help.

    Kevin

  • 0 in reply to Kevin Shafer
    TI__Mastermind 23765 points

    No problem.

    Best,

    Lucas