Clark Posted November 24, 2013 Share Posted November 24, 2013 Didn't know this going in but the Arduino board doesn't pump out enough strength on the I2C bus to send the signal much more than a few inches over clean wire. I'd like to drive an I2C display that connects via 3ft of ethernet cable (and a breakout board/jack on either end). When I use the CAT6 cable, the display corrupts after a few minutes and eventually the I2C bus will hang the Arduino! Read online about adding resistors and capacitors to sharpen the signal edges to increase the signal range but I have no scope to verify the results. And I've never manipulated signal edges like this so it would likely take me several evenings of guesswork if I can solve it all. I need to minimize how long the system is taken offline since it is responsible for temperature control in my tank. I'd really appreciate some experienced help with this. I can bring the system to your bench if I have to. Does anyone have some time, please, to take a look at my circuitry? Thanks very much Clark Link to comment Share on other sites More sharing options...
Clark Posted November 24, 2013 Author Share Posted November 24, 2013 Hmmm. This article is pretty straightforward so I'm adding two pullup R's and will soak test again... http://www.gammon.com.au/forum/?id=10896 Clark Link to comment Share on other sites More sharing options...
Clark Posted November 25, 2013 Author Share Posted November 25, 2013 I think this is solved. I added a 5.1k resistor between SDA and 5v, and another between SCL and 5v. The display has been running on the 3ft cable for 6 hours with no problems! Link to comment Share on other sites More sharing options...
victoly Posted November 25, 2013 Share Posted November 25, 2013 Woohoo ! Seemed like a pretty arbitrary limitation to have such short connection distances ! Link to comment Share on other sites More sharing options...
Clark Posted November 25, 2013 Author Share Posted November 25, 2013 I don't know that much about I2C really; I just learned about a few weeks ago. Pullups might be quite common. I think it was just bad luck on my part that the first tutorials I found on the web all dealt with small distances so none mentioned pullups, and a few problem threads I saw got crazy with multiple factors. And I was tired Once I finally found some better-written layman docs, it became straightforward. I hope to post some pics and info in the DIY section over turkey holiday. Link to comment Share on other sites More sharing options...
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