IOT SETUP - PIR SENSOR

This page logs my setup and ongoing experimentation for development of 'Internet of Things',

Specifically it describes the design and setup of a 'PIR' (Passive Infra-Red) Sensor module
and its setup in Home Assistant.

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For more information on PIR Modules see 'Passive Infrared Sensor' ... from ESPHome
Note that the device needs a 5-12 Volt supply and the ouput is 3.3 Volt logic level.

------ PIR Sensor Front View [from ESPHome]:

------ PIR Sensor Circuit board [from ESPHome]:

Using the Wemos (D1 Mini NodeMCU)

• The NodeMCU is programmed to detect PIR motion and generate MQTT messages

The PIR sensor will be managed by a NodeMCU wifi module
The chosen module is the 'Wemos D1 Mini'.
This module provides a simple clean interface and is easily programmed 'Over the Air'.


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------ Wemos D1 Mini NodeMCU:




• To test the behavior of the PIR a Test-Bed was constructed to experiment with the PIR settings.

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"PIR Circuit - NodeMCU (Wemos) Test Bed":




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"PIR Circuit - NodeMCU (Wemos) Schematic Test Bed":




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The above Fritzing diagrams show how the NodeMCU and the PIR are wired up.

As an initial setting adjust the 'Sensitivity' to half way, and the 'ReTrigger Time' to fully anti-clockwise.

Now we have to program the NodeMCU to run the test program.

Run the Arduino IDE and open a new 'Sketch' which contains some suggested code.

Select and Copy the all text from the following window.

Paste all the text (overwriting the new 'Sketch' suggestions).

'File => Save As' the Sketch 'NodeMCU-PIR-Test-01' .

Ensure that the 'Tools => Board:' is set to 'Generic ESP8266 Module'

and the board is selected as 'Node MCU' to ensure the correct names for pins

'Verify / Compile' the Sketch.

Connect the NodeMCU to a USB port,

Click on 'Tools => Port' and note the Port number is correct

Click on 'Tools => Serial Monitor' which will open a window showing all the serial comms

Down the bottom of that window ensure the speed is set to '9600 baud'

'Upload' the Sketch.

The Green 'Clock Tick' LED will start flashing (about 5 times per second)

When movement is detected by the PIR the Yellow 'PIR Detected' LED will light up.

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// Must be set to be a 'NodeMCU' in the Tools->Board Menu // for the Pin Numbers (D6 etc) to be recognised. int counter; void setup() { // Initialize digital pin 14 as Output. pinMode(D2, INTPUT); pinMode(D6, OUTPUT); pinMode(D5, OUTPUT); Serial.begin(9600); Serial.println("NodeMCU-PIR-Test-01"); counter = 0; } // the loop function runs over and over again forever void loop() { counter = counter + 1; digitalWrite(D6, HIGH); // turn LED on Serial.println("LED On"); delay(20); // wait 0.5 second digitalWrite(D6, LOW); // turn LED off Serial.println("LED Off"); delay(980); // wait for half a second if (counter > 9 ) { digitalWrite(D5, HIGH); // turn LED on Serial.println("PIR On"); delay(200); // wait 0.5 second digitalWrite(D5, LOW); // turn LED on Serial.println("PIR OFF"); counter = 0; } }




'NodeMCU-PIR-Test-01'


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• Slowly adjust the 'Sensitivity' Potentiometer screw until the optimum PIR Sensitivity is set.

Creating the Actual PIR Sensor

• A suitable box and installation must now be designed.
• Designing a layout of the actual 'PIR module' so that the adjustment screw can be accessed
• requires the 'PIR module' to be near the bottom of the box to prevent water access.
• Jaycar has a range of small boxes that are perfect. Outside mounting holes and reasonable sealing.
• Snap Fit ABS Enclosure 82 x 82 x 44mm Jaycar About $6.95
• Jiffy Box - Black with mounting flange - 83X54X31 - UB5 Jaycar Approx $3.75
• Bulkhead - Black - 88 x 69 x 33mm Jaycar About $4.75

------JAYCAR Snap Fit ABS Enclosure 'HB6008':

It may be possible to use one of the smaller cases - but I have chosen the larger 'HB6008' for easier fitting. This box mist be mounted with the flanges on both sides, and the Veroboard across the top edge. The PIR module is mounted on the bottom edge over against the Right Hand Side. The Sensitivity adjustment screw is accessed through a small hole drilled in the lower edge.

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"Actual PIR Circuit - NodeMCU (Wemos) Veroboard design":




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"Actual PIR Circuit - NodeMCU (Wemos) Veroboard Circuit Schematic":




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------ The Fritzing template for the Veroboard (bottom view):




• The correct size for the Jaycar 'HB6008' case is 28 columns by 14 rows.
• Cut the Verobaoard to that size along the next adjacent row of holes

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------ The Actual Verobord after tracks have been cut:




• These Tracks were cut with a 1.2mm ball engaving bit. Better results would have been obtained with a 0.8mm bit.

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------ The Top View of the Verobord showing which holes have to drilled through into the box.




• Remember the actual Veroboard is flipped over - so the copper tracks would be underneath.
• The three larger holes are for mounting, and the small holes are for mounting the LEDs.
• I would suggest doing the large holes first and then use screws to hold the board in
  place while the smaller holes are drilled.
• These are two small holes for each of the three LEDs which are later expanded to allow the
  LEDs' to poke through the box.
• [Take the Veroboard out and drill a small hole between each pair to use as a pilot hole for the LED.]
• The PIR Module requires a 22mm hole to be drilled through the case for mounting the 'PIR Module;

The Template as shown here is available for download as a pdf file.


• Template for ESP PIR Sensor Box-vero-scews-011.pdf -To download Right Click and 'Save File As'
• You may need the 'Adobe" to print this page - you must select 'Actual Size' (not 'Fit to Page') .
• It can then be printed - and will be actual size - which can be cut out and placed in the box.
• The 'hole' positions can then be marked with a centre punch and drilled when the template is removed.






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Last updated: 06-SEP-2021 at 1:04 PM.