Why is this circuit not burning my Arduino?

Other Hardware General Electronics
1

This is the connection instruction between my Arduino Uno and a DSC HS2032 panel.
The DSC panel uses 12V and I don't know the voltage fluctuation.
The yellow and green are RX/TX ports.

You can check the Github project here: dscKeybusInterface/KeybusReader.ino at master · taligentx/dscKeybusInterface · GitHub

DIAGRAM (I assume the vertical "+--+" part is a simple "OR" connection):

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

Why is this circuit not going to burn my Arduino?

2

Why do you think it would burn your Arduino? Because of "DSC Aux(+) --- Arduino Vin pin"? Go look at DSC Aux(+) in the HS2032 documentation and figure out the maximum voltage there.

Edit - ok I did your work for you today.

AUX+, AUX- Auxiliaryterminals. Use to power modules, detectors, relays, LEDs, etc. (700mA MAX). Connect the positive side of device toAUX+, the negative side to AUX-

So the Arduino is powered from the device, and the interface pins use voltage dividers to translate 12V to 5V levels. Nothing that would burn, normally. The Arduino can not safely power peripherals that consume very much current, when it is powered from VIN. But it can run, and control peripherals that derive power from somewhere else.