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MSP430F6459: Software I2C

Kum Hoo Lee
Expert 1855 points

Part Number: MSP430F6459

Hi,

Understand that MSP430F6459 only have 3 ports for I2C. And I would like to have another I2C port, as I know, I can use Software I2C to achieve what I need, but may I know what is the risk/Cons that I need to take care on this configuration? Will it be very unstable?

Hope to hear from you soon!

Thanks.

BR, KH

  • 0
    TI__Genius 15370 points

    Hi,

    May I ask why you need 4 I2C ports? If its a matter of adding another slave to the bus, this could be done on one of the other I2C connections you have available. This way you have more than just two devices that can communicate on the same bus.

    If you decide you need the extra port and decide to implement it via software, I have to warn you that it will probably be very difficult. I2C is very timing specific so you would most likely have to disable interrupts while communicating over your software I2C and potentially miss/delay communication over the other ports that are using interrupts from the USCI module.

    Finally, Software I2C on MSP430 MCUs is an application report on how to achieve what you are asking about. I recommend reading through it before trying to write your code. 

    Best regards, 

    Caleb Overbay

  • 0 in reply to Caleb Overbay
    Expert 1855 points
    Dear Caleb,

    Thanks for the reply. I am working on E meter. So need extra seperate port I2C to control Security IC. Any good suggestion?

    BR,
    KH
  • 0 in reply to Kum Hoo Lee
    TI__Genius 15370 points

    Hi,

    I still don't understand the need to include the security IC on its own I2C bus. The I2C protocol is setup to allow for multiple slave devices on the same bus. This way, you could use one of the already existing I2C ports instead of going with a device that has 4 or creating a new one via software. Adding the security IC to an already existing I2C bus is the route I highly recommend unless there are other circumstances keeping you from having multiple slaves on the same bus.

    Now, there are a few devices out there with 4 I2C ports that can be used, but as with anything it comes with trade-offs (memory, RAM, LCD, etc.). So if you decide to go this route you'll need to weigh your options:

    Device Comparison

    It may be helpful if you describe all the specifications of the I2C communication you're trying to achieve in order to pick the right part. 

    Best regards, 

    Caleb Overbay

  • 0 in reply to Kum Hoo Lee
    TI__Genius 15370 points
    Hi,

    Do you still need assistance with this issue?

    Best regards,
    Caleb Overbay

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