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Question about the I2C bus

Yi Yin1
Intellectual 430 points
Other Parts Discussed in Thread: AM3352

Hi, 

I have a question about the I2C bus.

In our system, there are two am3352 board  (board A and board B)connected with I2C. And in our program, the two am3352s was both set in "master transmitter". 

My Question:  What should be do in the situation as below?

When the "board A" generate "Start Condition"(I2C_IRQENABLE_SET.STT=1), the "board B" has generated the "Start Condition already, so the "board A" could not  generate it successfully, and the I2C_IRQENABLE_SET.STT does not become  "0".

In this situation, must I reset the I2C module?

I can not find any description about the step when the I2C_IRQENABLE_SET.STT does not become "0".

Thanks!

Yin

  • 0
    TI__Guru**** 393215 points

    Please do not double-post. You have posted already the same question on this thread: http://e2e.ti.com/support/arm/sitara_arm/f/791/t/332386.aspx

  • 0 in reply to Biser Gatchev-XID
    Intellectual 430 points

    Hi Biser Gatchev-XID 

    I am very sorry.

    I will delete this post . Is it right?

    Regards,

    Yin

  • 0 in reply to Yi Yin1
    TI__Guru**** 393215 points

    No, you can leave it. Somebody may answer here instead.

  • 0 in reply to Biser Gatchev-XID
    Expert 1530 points

    The what you are talking about is called a "Multimaster i2c".

    If collision (two masters initiate transmission simultaneously), one of them detects the case and shall lose arbitration: shall stop driving the i2c bus.

    Then, normally a retransmission occur initiated by that master. The other one will not even notice the collision (see the i2c specification).

    Shall you reset something? This depends on your environment. Normally not.

  • 0 in reply to sviss
    Intellectual 430 points

    Hi sviss

    Thanks for reply.

    In my case,  the arbitration lost interrupt was not detected. Because the two boards were not generate "Start Condition" simultaneously. 

    When the "board A" generate "Start Condition"(I2C_IRQENABLE_SET.STT=1), the "board B" has generated the "Start Condition already, so the "board A" could not  generate it successfully, and the I2C_IRQENABLE_SET.STT does not become  "0".

    I think that in this condition, the I2C_IRQENABLE_SET.STT should be reset to "1", let it to be a normal state. Is it correct?

    Is there any method  let the I2C_IRQENABLE_SET.STT to "1"?

     

    Thanks!

    Yin

     

     

  • 0
    TI__Guru**** 393215 points

    Merging this into a thread that's already opened by the same user on the same subject.

  • 0
    Intellectual 430 points

    Hi,

    Does anybody have any actual result about multimaster i2c?

    In another words, is there any actual result about the arbitration lost interrupt be detected?

    (I have to confirm that there is no bug about the arbitration lost interrupt. )

    Is the I2C module used in other device besides am335x?

    If yes, can  you tech me the name of device? 

     

    Thanks

    Yin

     

  • 0 in reply to Yi Yin1
    Expert 1530 points

    Yi Yin1 said:
    Is there any method  let the I2C_IRQENABLE_SET.STT to "1"? 

    Hi Yi Yin1,

    The Sitara has I2C_IRQENABLE_SET register (TRM 24.4.1.6). But I do not see anything called a STT there.

    I2C_CNT register has the bit named STT.

    If you described what you do and what you need, there would be better chance to give you a hint.

    Raw device programming? Linux driver?, Starterware?

    >>Is the I2C module used in other device besides am335x?

    Multimaster i2c is a requirement or ATCA (if you about this). Numerous implementations exist.