what am I seeing?? I2C Led Arduino

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I finally am getting some scan results.

But really have no idea what exactly it is that I am seeing.

I see a straight line high for 57.35us then a “start condition” low for 4.950us then a
high for 9.9us and a message WRITE TO: 0x51 =R/W=0. So where did/does 0x51 come from? That is not the address of my device.

RESOLVED
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Posted by Ralphxyz (Questions: 4, Answers: 7)
Asked on December 4, 2016 1:56 am
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Hi Ralph,

what you’re seeing is perfectly fine I2C signals!

The 0x51 can also be interpreted as 0xA2, depending on whether you read the address as 7 bit or 8 bit (including the R/W bit).

The slave device is acknowledging the packets, so it seems all fine to me.

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Posted by ikalogic (Questions: 0, Answers: 306)
Answered on December 4, 2016 9:44 am
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    Where does the 0x51 come from?

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    Posted by Ralphxyz (Questions: 4, Answers: 7)
    Answered on December 4, 2016 3:30 pm
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      Well, take a look at that: https://www.google.fr/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=0x51%20*%202

      0xA2 is 0x51 shifted by one bit to the left.

      In other words, 0xA2 is 0x51 + the R/W bit.

      In the file you provided the decoder had the option to “show slave address as : Address and separate R/W flag” that’s why you see 0x51. you may change this option though to get 0xA2.

      does that help?

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      Posted by ikalogic (Questions: 0, Answers: 306)
      Answered on December 4, 2016 5:17 pm
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        That is the thing I do not understand, the slave address is 0x3F not 0x51!!

        Is 0x51 the Master?

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        Posted by Ralphxyz (Questions: 4, Answers: 7)
        Answered on December 5, 2016 12:51 am
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          Ouch!
          The data you’re seeing is demo generated data !! (sorry for not noticing it before!)

          Demo data is generated when no device is connected to PC.

          Are you sure you SL2 is correctly detected by your machine?

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          Posted by ikalogic (Questions: 0, Answers: 306)
          Answered on December 5, 2016 1:26 am
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            Thanks,

            I have run an Arduino I2C scanner and it detects the slave as 0x3F.

            I am “trying” to write to a I2C LED, so far I can blink the backlight but not write to the LCD!

            Blinking the backlight implies that I am actually communicating with the device but I am not see
            anything but the demo in ScanaStudio 2.4.

            I have changed the address, then I can no longer blink the background so I “assume” 0x3F is the correct address.

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            Posted by Ralphxyz (Questions: 4, Answers: 7)
            Answered on December 5, 2016 1:33 am
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              This means the Scanalogic-2 is not detected by your system.

              Did you try another cable? another USB port? another machine?

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              Posted by ikalogic (Questions: 0, Answers: 306)
              Answered on December 5, 2016 8:46 am
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                Duh, my cable was unplugged..

                Thanks now I am seeing results.

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                Posted by Ralphxyz (Questions: 4, Answers: 7)
                Answered on December 5, 2016 1:50 pm
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                  Great, can i mark the post as solved?

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                  Posted by ikalogic (Questions: 0, Answers: 306)
                  Answered on December 5, 2016 5:06 pm
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                    Yeah, but I will be back with more related questions, hopefully I will have at least working examples
                    to question.

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                    Posted by Ralphxyz (Questions: 4, Answers: 7)
                    Answered on December 5, 2016 7:12 pm

                      Happy to help anytime :)

                      (ikalogic at December 5, 2016 8:47 pm)
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