I can't get to work a circuit that doesn't look that hard to copy.

This circuit was done for an Arduino extension of my DSC HS2032 system. I was trying the example "Status" on the Arduino's library DSC Keybus Interface v1.2.0.

On the example, we can see this circuit:

 *      DSC Aux(+) --- Arduino Vin pin
 *      DSC Aux(-) --- Arduino Ground
 *                                         +--- dscClockPin (Arduino Uno: 2,3)
 *      DSC Yellow --- 15k ohm resistor ---|
 *                                         +--- 10k ohm resistor --- Ground
 *                                         +--- dscReadPin (Arduino Uno: 2-12)
 *      DSC Green ---- 15k ohm resistor ---|
 *                                         +--- 10k ohm resistor --- Ground

Here on the photos, I'm showing what I have done.

enter image description here

DSC Panel wired

This is the HS2032 panel where (on the YEL and GRN) I connect the Arduino. I changed the Arduino's power source to be from my laptop so I could easily test it on the Serial Monitor. YEL->White/Green wire and GRN->Green wire

Now goes the Arduino's wiring.

Arduino wired

Remember from the panel, the yellow is the white/green and the green is the green (they are coming from the right). First, each of both wires goes directly to 15kOhm resistor. Secondly, it splits between a 10kOhm resistor which then ends up into Arduino's ground, or it goes directly to the Arduino's pin 3 or 5, depending on the cable.


The Serial Monitor shows "DSC Keybus Interface is online" and over.

If I connect green and white directly to 3 and 5, it will say sometimes "Keybus disconnected" and "Keybus connected" without any additional messages ever.

So my question is, am I missing something here? Why is the Serial Monitor not responding or what can I do to check where is the problem?


This are the serial monitor readings, nothing from the Panel. I had to connect without resistances to get this output, otherwise, the only output would be "DSC Keybus Interface is online."

08:26:32.359 -> 
08:26:32.359 -> DSC Keybus Interface is online.
08:26:35.345 -> Keybus disconnected
08:26:42.722 -> Keybus connected
08:26:47.838 -> Keybus disconnected
08:26:51.131 -> Keybus connected
08:26:54.937 -> Keybus disconnected
08:27:12.661 -> Keybus connected
08:27:17.122 -> Keybus disconnected
08:27:34.218 -> Keybus connected
08:27:41.697 -> Keybus disconnected
08:28:19.509 -> Keybus connected
08:28:22.487 -> Keybus disconnected
08:28:25.068 -> Keybus connected
08:28:28.053 -> Keybus disconnected
08:29:23.692 -> Keybus disconnected
08:29:31.175 -> Keybus disconnected
08:29:33.990 -> Keybus connected
08:29:37.005 -> Keybus disconnected
  • There's quite a lot of bare copper visible. Is that mains power? Jul 27 '20 at 10:13
  • I don't see the connection between AUX- and Arduino ground. You need common ground between them
    – chrisl
    Jul 27 '20 at 12:43
  • @marcellothearcane if you are talking about the first photo, the RED, BLK, YEL and GRN are used for direct connections to the original keypad. More on the left, you can see the siren wiring. There is also one copper coming out of BLK, it is the blue wire bended to fit properly.
    – J. Francis
    Jul 27 '20 at 15:04
  • @chrisl excelent. I will take a wire from DSC Aux (-) (we can't see it on the images) to the breadboard's GND ground, finally going to the Arduino's GND ground through the black wire. Will tell you how it goes!
    – J. Francis
    Jul 27 '20 at 15:08
  • 1
    The schematic you drew does not match the ASCII circuit you copied. You need to swap the GND and Arduino wires on the resistors. Jul 28 '20 at 6:42

Is this circuit properly made?


A lot of the problem is that you don't have a well-drawn schematic. I think that what you have is a couple of voltage dividers to interface a 5V arduino with a higher voltage device. I suspect a voltage divider isn't the best solution but presumably it works for someone else. So what you need is ...


simulate this circuit – Schematic created using CircuitLab

If I were you I'd pull your existing wiring apart completely and start again, arranging the components and wires so that they match this schematic as closely as possible in terms of position and orientation. Then trace the connections through carefully to make sure everything matches.

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