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I need to receive a 24V signal from an automated industrial system. The receiving board is a UDOO system that its I/Os can handle voltages until 3.3V.

Any ideas on how can I make things work?

m.Alin
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sample_nickname
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  • Is it an analog or digital signal? What is the bit-rate/slew rate of the signal? Seriously, more info. – Dzarda Mar 26 '14 at 15:31
  • I know there is valuable info missing, but I currently don't have any. What are the scenarios? – sample_nickname Mar 26 '14 at 15:36
  • Forget about scenarios - scenarios take time to figure out and even then they may not cover all eventualities when you do come up with answers - in other words, please provide the information. – Andy aka Mar 26 '14 at 16:04
  • Usually industrial systems use [4-20mA](http://en.wikipedia.org/wiki/Current_loop) signals in which case an optocoupler will not help. – alexan_e Mar 26 '14 at 16:13
  • With very little to go on from the OP, my answer assumes a logic signal; I have clarified in the answer. – akellyirl Mar 26 '14 at 16:24

1 Answers1

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I think your best solution (assuming this is a logic signal and not power), is an Opto-Coupler.

See this previous question: Optocoupler input protection

It isolates the the 3.3V circuits of the Udoo from the 24V. The isolation is good to several kV usually.

This is a typical arrangement:

enter image description here

Community
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akellyirl
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  • Bear in mind this will invert the logic of the signal; when Vin is 24V, the micro pin will be low.. But it is easy to rearrange the circuit to not invert, or just to deal with the inversion in the micro. Also your pullup should go to 3.3V instead of 5V to meet the stated requirements. – Martin Mar 26 '14 at 16:13