What is that black thing plugged in next to the PIR connector?
As near as I can tell:
The Black wire is Power and goes to Arduino +5.
The Brown (center) wire is Ground and goes to Arduino Ground.
The Red wire is the signal. It connects to an Arduino digital input pin. It needs a pull-up resistor but you can use the internal one like this:
const int PIRpin = 3; // Or whatever pin you have it connected to
void setup() {
pinMode(PIRpin, INPUT);
digitalWrite(PIRpin, HIGH); // Enable the internal pull-up resistor
}
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