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    EMO-R8 intermittently not seen by i2c

    UniPi 1Wire Extension Modules (official)
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    • M
      Merv last edited by

      Hi,
      I'm running a unipi with an EMO-R8 extender, and a 1W-R4-DI4 for my home automation.
      when I run
      i2cdetect -y 1
      I can see address 21 show up, and if it does, the evoc program web page allows me to see the relays 9 through 15 (EMO-R8) and to turn them on and off. BUT: Sometimes address 21 is not there, and I need to pull the i2c data cable from the expansion board for a few minutes, and then put it back to allow the expansion board to be seen.

      What might be wrong with my setup?

      Merv.

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      • ?
        Guest last edited by

        Hello Merv,

        do you have the possibility to check the cable between UniPi and Emo-R8, maybe re-rcimp it if you have the tool?

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        • M
          Merv last edited by

          Hi, I checked it visually, and checked all pins were tight with a small screwdriver, and the cable seems ok. The Data light is coming on on the EMO-R8. but it's still intermittent…. I'll bring home a Multimetre and try belling out the cable, but I think it's ok....

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          • ?
            Guest last edited by

            It might also be caused by a ESD from a near power relay or a frequency changer… So maybe some shielding might help. Can you provide a picture of your setup?

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            • M
              Merv last edited by

              I think this may be the issue, I have it installed right beside the 12V transformer…...

              Appologies for the link, I used to know how to get the url of an image in Flickr, but it seems they have changed how it works...

              https://www.flickr.com/photos/mervcolto ... ed-public/

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              • ?
                Guest last edited by

                Yep, the I2C bus not much resistant to the EMC. I have a few ideas:

                • shield the I2C cable with aluminium foil and lead the cable under the din rail which you use for the blue cables

                • place the EMO-R8 insted of the 1Wire hub or 1Wire relay/input board

                By the way, very nice installation!

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                • M
                  Merv last edited by

                  Hi,

                  I wrapped the I2C cable in tinfoil, and it worked! That was the problem.

                  If I am re-wiring the system, I'll re-arrange to keep the cable away from the power supply, but the tinfoil trick is fine for now.

                  I've been checking it each day for the last 4 or 5 days and it's perfect.

                  Tomas, Many thanks for the great support work you do here.

                  Merv.

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                  • ?
                    Guest last edited by

                    I am glad it helped. Thank you Merv

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                    • R
                      RobRemote @Guest last edited by

                      Hi Guest , wat is the maximum length of the I2C Cable? I want to make one of 2 meters length , Is that gonna be a problem ? I am gonna use shieldet cable to prevent esd . Kind regards , Rob

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                      • T
                        tomas_hora administrators @RobRemote last edited by

                        @RobRemote 2Meters is pretty far. I2c is not designed to work on such distances.... But you might be lucky.

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