EMO-R8 intermittently not seen by i2c



  • 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.



  • 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.



  • 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?



  • 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....



  • 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?



  • 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/



  • 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!



  • 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.



  • I am glad it helped. Thank you Merv



  • 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


  • administrators

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