PIR Sensor analog value oscillation?

Projects General Guidance
10

Hi all,

Thank you very much for taking the time to reply. I'll try to respond to each of the questions & comments I saw in the replies. Here is a block diagram of what I'm trying to do (with pin names):

ControllerBlockDiagram
ControllerBlockDiagram1484×705 17 KB

Note 1: this block diagram doesn't show the second 12VDC output which will be connected to the relay module. I couldn't figure out a good way to include it without severely cluttering the diagram and it's not relevant to the problem I'm asking about right now.
Note 2: for the PIR issue I'm troubleshooting right now I'm powering the Arduino via USB and the relay module is not attached to power or the Arduino's analog pins. I will come back to powering and switching the receptacle once I have the low voltage side working.

koraks: The picture accurately shows how I have things connected.

BoxPics
BoxPics1012×774 97 KB

The LED Driver came from Amazon (120VAC to DC 12V 1A LED Driver). I'm having trouble finding an official data sheet for it, but I will keep looking. Here is a better view:
LEDDriver
I have the "Output -" terminal on the LED driver connected to the "Input -" terminal on the DC-to-DC converter and to the GND pin on the Arduino. The "Output -" terminal on the DC-to-DC converter is connected to the GND pins on my PIR and audio board. Here's a better picture of the converter:
DcToDc
Should I be ignoring the DC-to-DC converter's Output- and using the one from the LED driver to make sure all of my low-voltage stuff has a common ground? I hadn' t heard of a fixed-current led driver, so that was not part of my parts search and I probably didn't end up getting one.

I chose to power the Arduino through the VIN pin using 12VDC because I wanted the 5V pin to power the relay module. I also found a lot of conflicting (or at least confusing) information about whether the 5V pin can be used to power the Arduino or only as an output. My understanding is that the VIN pin goes through the Arduino's regulator, which can cause the input voltage to drop, so I thought the input needed to be higher than 5V for that to work.

TomGeorge and dave-in-nj: I missed reading the forum guidelines before, but I have read them now. I have been developing the code in stages; and as you suggested I have been troubleshooting this PIR issue with code that does nothing but read the PIR and put the read-in analog value out to serial.

#define PIR_1_INPUT_PIN               A5    // PIR 1, analog input pin

int bOn = HIGH;
int triggerCount = 0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200); //we talk to the PC at 115200
  delay(100);

  pinMode(PIR_1_INPUT_PIN, INPUT);
  pinMode(13, OUTPUT);

  Serial.println("Starting up...");
}

void loop() {
  // put your main code here, to run repeatedly:

  int aPirValue = analogRead(PIR_1_INPUT_PIN);

  Serial.print("Pir 1 value: ");
  Serial.println(aPirValue);

  digitalWrite(13, bOn);
  if (bOn == HIGH)
  {
    bOn = LOW;
  }
  else
  {
    bOn = HIGH;
  }

  delay(500);
}

The images pasted into the diagram in my original post (other than the generic 110vac receptacle) are pictures of the actual components I'm using. The object labeled 'To PIR' is the Ethernet port I plug the PIR cable into. It is wired so that it uses 3 conductors out of the cable's 8 (5VDC, GND, and signal). I forgot that the PIR itself isn't in the diagram. Here it is - I got it from eBay several years ago and it is not clearly marked with any part number so I don' t have a datasheet readily accessible:
PIR

I can modify the design so that it switches the hot wire instead of the neutral. The receptacle I'm using is a GFCI outlet so there isn't a tab between the two outlets to break off or I would definitely take that advice. When I did plug everything in as shown in the block diagram above I had another issue with the GFCI, but I figured I would save that for another post once I make sure the Arduino side is running and activating the relays properly. For the PIR issue I'm looking into now I have the Arduino out of the box, powered by a USB cable so I can see the serial output, and running the simplified sketch above. Nothing is connected to it other than the PIR.

I haven't plugged a lamp or anything into the outlet yet, but I'm sure that house power is reaching the LED driver; I measured 110VAC going in one side and 12VDC coming out the other. The DC-to-DC converter has an LED on it which lights up and I measured 12VDC in and 5VDC out.

I chose not to power the PIR and sound module from the Arduino just due to a shortage of output pins.

bluejets: when you say the LED driver could be downright dangerous, can you clarify? Is the danger to me, my other components, or all of the above? :slight_smile:

Thanks again for all of your help, and I will try to clarify anything that I've made confusing.

Mike