G+_Sean Miller Posted March 11, 2018 Share Posted March 11, 2018 I have a 20% project I've been mulling over for work. I need an arduino to control about 2 dozen relays. And I want to remote control that arduino with another arduino in a handheld box connected via a 100' cat5 cable. I want i2c lcd screens and big mashable arcade buttons connected to both arduinos. What would be a good protocol to send over the cat5 cable? i2c? RS485? SPI? serial? CAN? Preferably not ethernet. Can arduinos talk to each other and their lcd screens on the same i2c? Can I use SPI and i2c at the same time? What if I had just one arduino talk to both lcd screens? If I slow down the baud rate, can I go farther? I don't need superfast bitrate. Can I send a power voltage over an unused twisted pair of the Cat5? how many milliwatts can I power with it? I have a decent idea how to do the rest of it like wiring the buttons and the relays. Thank you very much for your help. Sincerely, Sean Link to comment Share on other sites More sharing options...
G+_Mike Kelly Posted March 11, 2018 Share Posted March 11, 2018 We used this shield: museduino.wordpress.com - FAQ Link to comment Share on other sites More sharing options...
G+_Black Merc Posted March 11, 2018 Share Posted March 11, 2018 RS485 is a serial proto. Personally seen used in industrial setting to relay data from multiple machines(+12) to a centralized monitoring station for production status. Also over a distance of +100 feet. Link to comment Share on other sites More sharing options...
G+_Ben Reese Posted March 14, 2018 Share Posted March 14, 2018 https://www.youtube.com/user/SuperHouseTV SuperHouseTV Does something very similar and his videos go over the different designs he's used to build a DIY smart home. A quick search, it seems i²c and SPI are both limited to about 10 ft - even if the baud rate is reduced, so probably wouldn't work for you (can't hurt to try though). Serial may work. Really, ethernet may be the most reliable if your wanting to transmit messages. Perhaps even put them on a network tied to an MQTT broker? You can definitely use spare wires to carry voltage. At 500 mA, 24 AWG wire will drop 5v down to <4 over a 100' run. Instead, it would probably be better to push 12v through the wire and use a UBEC or voltage regulator on the other end to power your electronics. There's my 2¢. Would love to hear more about how your project goes. Link to comment Share on other sites More sharing options...
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