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I want to do a connection of multiple current and voltage meters, they connect by I2C. Is for to monitor solar panels and batteries, they will be a considerable distance from the master. I thinking use a 6P6C or RJ45 connectors for this. But first I want to know if there is a standard for cable colors or another type of connector for this, just for follow the protocols in case I want to expand my system or buy a new device.

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    \$\begingroup\$ I doubt it. I2C wasn't originally designed to be used with such connectors. \$\endgroup\$
    – DKNguyen
    Jun 16, 2020 at 21:08
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    \$\begingroup\$ For long distance, use one of these: sparkfun.com/products/14589 \$\endgroup\$
    – Michael
    Jun 16, 2020 at 21:15
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    \$\begingroup\$ use lan cables ... that way you are not forced to make your own \$\endgroup\$
    – jsotola
    Jun 16, 2020 at 21:20
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    \$\begingroup\$ DrakoPD - If you are concerned about (or didn't know about) the issues when using I2C over a long distance (which you mention you are doing "in passing" in the question), use the search box above and try the search term - I2C long distance - to see previous Q&A on the topic. \$\endgroup\$
    – SamGibson
    Jun 16, 2020 at 21:38
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    \$\begingroup\$ You can use a TRS (3 wire) 3.5mm jack and cable for SCL, SDA and GND but, yes, I2C wasn't designed for this, and the signal might degrade over the length of the cable, especially at higher frequencies. \$\endgroup\$
    – QuickishFM
    Jun 16, 2020 at 21:39

2 Answers 2

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I2C specification does not specify any connector, as it is not a specification for an external interface. Many technologies that are based on I2C do specify a connector and pinout for an external interface, for example Access.bus has 4-pin connector. Lego Mindstorms also implements I2C over 6P6C connectors.

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See Access.bus, a form of I2C designed for low-speed desktop devices with hot-plug capability. Unfortunately, it was quickly overshadowed by USB, which came out shortly afterward.

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