• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 132 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMH1218EVM: Can some pins be NC on USB2ANY programming header in SMBUS mode?

Jacob Revelo
Prodigy 20 points
Part Number: LMH1218EVM
Other Parts Discussed in Thread: USB2ANY, LMH1218

Tool/software:

If only using SMBUS I2C mode in SigCon Architect, will programming still work if I just jumper wire pins 5, 9, 10, and 6 (with J4 7-8 and 9-10 shorted) between the EVM header and the USB2ANY, or do pins 2, 4, 8, and 3 on J3 also need to be connected to the USB2ANY programmer?

I know for SPI mode that Resistors R26-R31 level convert to 2.5V, but is there a reason they are still connected for SMBUS mode as a pull down or are they unused? Similarly, it's not clear if pin 3 is used by the USB2ANY in SMBUS since this is the address bit registered by the LMH1218 device to set the I2C address and set through a resistor.

  • +1
    TI__Mastermind 32325 points

    Hi Jacob,

    Jacob Revelo said:
    will programming still work if I just jumper wire pins 5, 9, 10, and 6 (with J4 7-8 and 9-10 shorted) between the EVM header and the USB2ANY,

    Yes the only signals necessary for I2C access should be SDA, SCL, GND, and 3P3V (pins 10, 9, 6, 5).

    Jacob Revelo said:
    is there a reason they are still connected for SMBUS mode as a pull down or are they unused?

    These pulldowns would not be used in I2C mode, as the SCL and SDA lines are not connected to these pulldowns.

    Jacob Revelo said:
    Similarly, it's not clear if pin 3 is used by the USB2ANY in SMBUS since this is the address bit registered by the LMH1218 device to set the I2C address and set through a resistor.

    I believe the intention is to allow J3 to support SPI with the MISO signal on pin 3. Leaving pin 3 disconnected in I2C mode should be ok, as you wouldn't use this signal.

    Best,

    Shane