Today we will talk about how to use Arduino collect security system. Our “security” will guard one circuit and control one siren.
For Arduino this is not a problem, and, as you will see from the program code and the device diagram, you can easily increase the number of protected access points and the number of notification or indication devices.
Security system can be used to protect both large objects (buildings and structures), and small items (boxes, safes), and even portable cases and suitcases. Although you need to be careful with the latter, if you install a security system, for example, on a suitcase with which you decide to travel, and the warning system goes off at some airport, then I think you will have a serious conversation with the local security service :-)
A simplified operating principle of the device is as follows (Fig. 1). After turning on the power, the device goes into operating mode and waits for arming. Arming and disarming are carried out with one button. To increase security, it is better to place this button inside a protected area (safe or box). Before turning on the security mode, the door must be opened slightly. When you turn on the security mode (press the button), the electronic circuit waits until you close the door to the room (safe door, box lid, etc.).
A limit switch of any type must be installed on the door (or door), more on that later. By closing (or opening), the limit switch will inform the device that the protected circuit is closed, and the device will go into security mode. The system will notify you about entering the security mode with two short signals (like in car alarms). In this mode, the device “catches” the opening of the door. After opening the door, the system waits a few seconds (this is an adjustable value, about ten seconds for rooms, one or two for a box) for the security mode to turn off; if this does not happen, the siren turns on. The algorithm and circuit are designed in such a way that you can turn off the siren only by completely disassembling the housing and turning off the power.
Device security system very simple (Fig. 2). Based on the board Arduino. The limit switches are connected like a regular button, through pull-up resistors. I will dwell separately on the end switches. They are either normally closed or normally open. You can turn on a regular button as a limit switch, only the travel of a regular button is very large, the door backlash is usually greater. Therefore, it is necessary to come up with some kind of pusher for the button and spring it so as not to break the button with the door. Well, if you’re not too lazy, you can go to the store and buy a magnetic switch (reed switch) (Fig. 3), it is not afraid of dust and dirt.
A limit switch for car alarms is also suitable (Fig. 4). It should be noted that the program is written for a reed switch. At closed door its contact is closed. If you use a car alarm switch, then when the door is closed it will most likely be open, and in the appropriate places in the code you will need to change 0 to 1 and vice versa.
As a siren, I propose to use the PKI-1 IVOLGA sound siren, produced in Belarus (Fig. 5). Supply voltage 9 - 15 V, operating current 20 - 30 mA. This allows it to be used with battery power. At the same time, it “produces” 95 - 105 dB.
With such characteristics, it will sound for several tens of minutes from a Krona battery. I found it on the Internet for 110 rubles. There, a reed switch with a magnet costs about 30 rubles. The car alarm switch was purchased at auto parts for 28 rubles. The KT315 transistor can be taken with any letter or replaced with any modern low-power silicon transistor of appropriate conductivity. If the volume of one siren is not enough (who knows, maybe you want it to be heard from many kilometers away), you can connect several sirens in parallel or take a more powerful one, only in this case the transistor must be replaced with a more powerful one (for example, the familiar transistor assembly ULN2003). As connectors for connecting the reed switch and siren, I used the simplest connectors for audio/video devices - the price on the radio market is 5 rubles. for a couple.
The device body can be glued together from plastic or plywood; if a serious object is being protected, then it is better to make it metal. To increase reliability and safety, it is advisable to place batteries or accumulators inside the case.
To simplify the program code, energy-saving elements were not used, and the batteries do not last long. You can optimize the code, or even better, radically remake it by using interrupt event processing and MK sleep mode. In this case, the power from two square batteries connected in series (9 V) should be enough for several months.
Now the code
// constants
const int button = 12; // pin for the button
const int gerkon = 3; // pin for reed switch
const int sirena = 2; // siren control pin
const int led = 13; // indicator pin
// variables
int buttonState = 0; // button state
int gerkonState = 0; // reed switch state
int N = 0; // disarm button counter
void setup() (
// control siren and indicator - output
pinMode(sirena, OUTPUT);
pinMode(led, OUTPUT); // button and reed switch - inputs
pinMode(gerkon, INPUT);
pinMode(button, INPUT);
}
void loop()
digitalWrite(led, HIGH);
while(buttonState= =0)( // wait loop until we press the button
buttonState = digitalRead(button); // to switch to security mode
}
digitalWrite(led, LOW);
buttonState = 0; // reset the button value
while(gerkonState= =0)( // loop until we close the door
}
delay(500); // :-)
digitalWrite(sirena, HIGH); // Code
delay(100); // indications
digitalWrite(sirena, LOW); // enable
delay(70); // mode
digitalWrite(sirena, HIGH); // security
delay(100); // alert
digitalWrite(sirena, LOW); // sound
while(gerkonState= =1)( // wait for the door to open
gerkonState = digitalRead(gerkon);
}
for (int i=0; i<= 5; i++){ // 7,5 секунды на нажатие
buttonState = digitalRead(button); // secret button
if (buttonState = = HIGH) ( // track ours - someone else's
N=N+1;
}
delay(1500); // secret feature :-)))
}
if (N > 0) ( // the most important thing
digitalWrite(sirena, LOW); // don't turn on the siren
}
else(
digitalWrite(sirena, HIGH); // or turn on the siren
}
digitalWrite(led, HIGH); // turn on the indicator N = 0;
buttonState = 0;
delay(15000); // reminder for dummies who like
digitalWrite(led, LOW); // press the buttons without interruption delay (1000);
Spring, as you know, is accompanied by all sorts of aggravations, and now the main “exacerbation” has crawled out of its holes onto the street in order to appropriate for itself what does not belong to it. This means that the topic of protecting your property is becoming more relevant than ever.
The site already has several reviews of homemade ones. They are of course functional, but everyone has general feature- dependence on the outlet. If this is not a problem with a property where electricity is already supplied, then what about a property where the outlet is far away or the surrounding area is completely de-energized? I decided to take a different route - to assemble a long-lived device that is as simple as possible and independent of mains power, which will sleep all the time, and when robbers break in, it will start up and call the owner’s phone, signaling with a simple alarm call.
Review Items
Purchased:1. Bread board single sided 5x7 cm: getinaks- or fiberglass
* - fiberglass is much better quality than getinax.
2. Neoway M590 module - with antenna on PCB -
3. Arduino Pro Mini "RobotDyn" ATmega168PA 8MHz 3.3V -
4. Lithium charge-discharge control board -
Mined from the ruins of civilization:
1.
Racks for boards, cut from device housings - 6 pcs.
2.
Lithium flat battery 1300mAh
3.
Staples used to secure the cable to the wall
4.
Stationery eraser
5.
Copper wire 1.5mm thick
6.
Instrument housing from the local radio market - 1.5$
7.
A pair of LEDs of different colors (taken from a VHS player)
8.
Antenna and button with cap (taken from Wi-Fi router)
9.
4-pin terminal block (taken from dimmer)
10.
Power connector (taken from an old charger for 18650)
11.
6-pin connector (taken from DVD drive)
12.
Can(from coffee for example)
Arduino Pro Mini "RobotDyn" Atmega 168PA 3.3V 8MHz
Specifications:Microcontroller: ATmega168PA
Direct operating voltage:.8 - 5.5 V
Operating voltage through stabilizer LE33: 3.3 V or 5 V (depending on model)
Working temperature:-40°C… 105°C
Input voltage: 3.35-12V (3.3V model) or 5-12V (5V model)
Digital Inputs/Outputs: 14 (6 of which can be used as PWM outputs: 3, 5, 6, 9, 10, and 11)
Analog inputs: 6
Timers-counters: two 8-bit and one 16-bit
Energy Saving Modes: 6
DC current via input/output: 40 mA
Flash memory: 16 KB (2 used for bootloader)
RAM: 1 KB
EEPROM: 512 bytes
Memory recording/erasing resource: 10,000 Flash/100,000 EEPROM
Clock frequency: 8 MHz (3.3 V model) or 16 MHz (5 V model)
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK)
I2C: A4 (SDA) and A5 (SCL)
UART TTL: 0 (RX) and 1 (TX)
Datasheet:
The choice fell on this atmega completely by accident. On one forum where energy-efficient projects were discussed, in the comments there was advice to use the 168th atmega.
However, I had to tinker to find such a board, since quite often all the lots were filled with 328 atmegs at a frequency of 16 MHz, operating from 5V. For my project, such characteristics were redundant and inconvenient from the very beginning, and the search became more complicated.
As a result, I came across a 3.3-volt version of Pro Mini on Atmega 168PA on eBay, and not just a simple Chinese one, but under the RobotDyn brand from a Russian developer. Yes, at first, like you, I also had a grain of doubt. But in vain. When the project was already assembled, and AliExpress introduced mandatory paid delivery for cheap goods (after which parcels began to get lost much more often), I later ordered a regular Pro Mini Atmega168 (without PA) 3.3V 8MHz. I experimented a little with power saving modes with both boards, flashing a special sketch into each that put the microcontroller into maximum power saving mode and this is what came out:
1) Arduino Pro Mini "RobotDyn": ~250µA
2) Arduino Pro Mini “NoName”: when power is supplied to the voltage stabilizer (RAW pin) and the LED is soldered, the current consumption is ~3.92mA
- as you understand, the difference in energy consumption is almost 16 times, all because NoName's Pro Mini uses an Atmega168+ combination, of which the MK itself eats only 20uA current (I checked this separately), all the rest of the gluttony is accounted for by the AMS1117 linear voltage converter - the datasheet only confirms this: 
In the case of the board from RobotDyn, the combination is somewhat different - this is the Atmega168PA+ - here a different LDO stabilizer is used, whose characteristics in terms of energy saving turned out to be more pleasant: 
I didn’t desolder it, so I can’t say how much current the Atmega168PA consumes in its pure form. In this case I had enough ~250µA when powered by Nokia lithium battery. However, if you unsolder the AMS1117 from the NoName" motherboard, then the regular ATmega168, in its pure form, as I said above, consumes 20uA.
LEDs with power supply can be knocked off with something sharp. It's not a problem. The stabilizer was desoldered with a hairdryer. However, not everyone has a hair dryer and the skills to work with it, so both of the above options have a right to exist.
Neoway M590E module
Specifications:Frequencies: EGSM900/DCS1800 Dual-band, or GSM850/1900 or Quad-band
Sensitivity:-107dBm
Maximum power transmission: EGSM900 Class4(2W), DCS1800 Class1(1W)
Peak current: 2A
Working current: 210mA
Sleep current: 2.5mA
Working temperature:-40°C… +85°C
Operating voltage: 3.3V…4.5V (recommended 3.9V)
Protocols: GSM/GPRS Phase2/2+, TCP/IP, FTP, UDP etc.
Internet: GPRS CLASS 10
Datasheet:
The cheapest GSM module that can be found on the market, usually used, soldered not always by skillful with Chinese hands from equipment. Why not always dexterous? Yes, all because of desoldering with a hairdryer - often people receive these modules with shorted plus and minus, which is one of the reasons for their inoperability. Therefore, the first step is to check the power contacts for a short circuit.
Note. I would like to note a separate important point, in my opinion, that these modules can come with a round coaxial connector for the antenna, which allows you to separately order a more serious antenna and connect it to the module without dancing with a tambourine. Or they may come without this connector. This is if we talk about the cheapest sets. If you don’t want to rely on a happy accident, then there are slightly more expensive sets where this connector is present + the kit includes an external antenna on a textolite board.
This module is also capricious when it comes to power supply, since at peak it consumes up to 2A current, and the diode included in the kit seems to be designed to lower the voltage from 5V (which is why it says 5V on the board itself) to 4.2V, but judging by According to people's complaints, it creates more trouble than it is worth.
Let's say you have already assembled this module, and instead of a diode, a jumper is soldered in, since we are not going to supply a voltage of 5V to it, but will power it directly from a lithium battery, which is within the permissible voltage limits of 3.3-4.2V.
It will be necessary to somehow connect it to the computer and check for functionality. For this case, it is better to buy one for yourself in advance - through it we will communicate with the module and Arduino boards via the UART serial interface (USART).
The connection is shown below in the picture (I drew it as best I can):
TX modem >>> RX converter
RX modem<<< TX конвертера
Battery plus - Modem plus
The negative of the lithium battery is combined with the GND of the modem and the GND of the converter
To start the modem, apply the BOOT pin through a 4.7 kOhm resistor to GND
In the meantime, run the program on your computer. Pay attention to the settings:
1) Select the COM port to which the TTL converter is connected, in my case it is COM4, yours may be different.
2) Select the data transfer speed. (There is a nuance here, because the modules themselves can be configured for different speeds, most often 9600 baud or 115200 baud. Here you need to select it empirically, choosing some speed, connecting, and sending the AT command, if the cracks come in response, then it will disconnect , select a different speed and repeat the command, and so on until the answer is OK).
3) Select the packet length (in this case 8 bits), parity bit disabled (none), stop bit (1).
4) Be sure to check the box +CR, and then a carriage return character will be automatically added to each command we send to the module at the end - the module understands commands only with this character at the end.
5) Connection, everything is clear here, click and we can work with the module.
If you click on “Connection” and then start the module by applying BOOT through a 4.7K resistor to ground, then first the terminal will display the inscription “MODEM:STARTUP”, then, after a while, the inscription “+PBREADY”, meaning that the telephone number has been read book, even though it may be empty: 
Under this spoiler are AT commands with examples
We print the AT command - in response, the module sends us our command, since the echo mode is enabled, and OK: 
Let's check the status of the modem with the AT+CPAS command - the response is again our command, +CPAS: 0 and OK.
0 means that the module is ready for operation, but depending on the situation there may be other numbers, for example 3 – incoming call, 4 – in connection mode, 5 – sleep mode. I couldn’t find any information on 1 and 2. 
Changing the data transfer rate via UART is done with the command AT+IPR=9600 - this is if you need a speed of 9600. If something else, similar to AT+IPR=19200, for example, or AT+IPR=115200. 
Let's check the network signal. AT+CSQ, the response comes +CSQ: 22.1 - the value before the decimal point has a range of 0... 31 (115... 52 dBl) - this is the signal level, the higher the better. But 99 means its absence. The value after the decimal point is the signal quality 0... 7 - here it’s the other way around, the lower the number, the better. 
Let's disable echo mode by sending the ATE0 command so that duplicate commands do not interfere. This mode is switched back on using the ATE1 command. 
View firmware version AT+GETVERS 
These and many other commands can be viewed
Aligning boards
If soldering the Pro Mini to a breadboard is not difficult, then with the GSM module the situation is somewhat more complicated, because its contact comb is located only on one side, and if you solder only it, then the other side of the board will simply hang in the air. Then, again, I had to drill additional 3 holes by eye near the three corners on the board. The areas around each of the holes were then masked off. For convenience, I placed the disconnected leads from the comb on a solderless breadboard (white) and, installing the GSM module board on them, soldered them normally:
Later I had to make another hole, in my case on the letter “I”, where it says “Made In China”, from the edge of the board. 
It turned out that the added contact, which is essentially GND, became located next to the GND of the Pro Mini board, and thus it became possible to connect the ground of the GSM module and the Pro Mini with a drop of solder (the long pin in the middle and the Pro Mini pin to the right of it) - I marked them with arrows. Of course it turned out a little crooked, but now it holds securely: 
There was some space left between the boards - in it I placed a lithium discharge charge control board with a pre-soldered microUSB connector and soldered wires. 
The scarf fits in there very tightly, and the glow of the LEDs on the side will be clearly visible through a small hole in the case. 
Card racks
In order to securely mount the board inside the case, I had to spend a couple of days thinking about how this could be implemented. The option with hot-melt adhesive was not considered for several reasons - it could fall off, become deformed, and most importantly, the structure would be difficult to disassemble.I came to the conclusion that the simplest and most correct option here would be to use stands, which naturally I did not have. However, there were a couple of non-working chargers, from which one long stand with a thread for self-tapping screws was cut out. Each stand was sawn in half and filed down to about 9.5mm - it is at this height that the battery located under the board has a sufficient margin of about 2mm - this is done so that the soldered contacts of the board with their tips do not touch it and so that it is possible to put a piece between them foam for fixation.
As for attaching the board directly to the case, here I cut four strips from a coffee can, drilled a hole at the ends of which, then secured them on the same screws that are screwed into the racks. See in the photo below what it looks like.
The next step is to screw a couple of stands on the other side of the board, that is, on top, so that when the case is closed, the cover rests slightly on these stands, creating additional fixation. A little later, for this purpose, I came across a housing from a Soviet propaganda radio (if it had been found earlier, I would have taken all the stands from here), where I found a couple of more or less suitable heights, but first I drilled them in the center with a drill under self-tapping screws Then I sawed them off and also finished them off with a file, removing the excess. Here I came up with one subtlety - in the photo you can see that one white stand is screwed to the getinaks board from the edge, and the other white one is screwed directly to the module board, because from one edge the modem board completely covers the bottom board, and from the opposite edge - on the contrary - the bottom one is already peeking out. At the same time, additional holes had to be drilled in both boards so that the heads of the screws could pass freely.
And finally, it remains to make sure that the board is always parallel to the body - the staples that are used to fix wires and cables on the wall are perfect for this task; I previously removed the nails from them. The brackets cling well to the board with the concave side without any additional devices, the only thing is to the right of the SIM card, the width of the bracket turned out to be excessive and I also had to sand it.
All details were adjusted by eye and experimentally, below is a photo of all of the above:
Connectors. LEDs. Button.
Since I ran out of comb, I had to remove the 6-pin connector from the DVD drive board, which I then soldered to the Pro Mini, this is for the convenience of flashing the board. Nearby I soldered a round connector (Nokiev 3.5mm) for charging lithium.
The body of the 6-pin connector was slightly finished with a file, because its edges protruded slightly above the body. The charging socket fits perfectly against the wall of the case. 
On the other side of the board, I soldered a button to reboot the device and two LEDs for debugging the firmware - the red LED is connected to the GSM module, the second green LED is connected to the 10th pin of the Pro Mini - it’s easier for me to debug the program. 
Battery modification
The flat Nokia battery from Nokia phones is no less common than the 18650, but many simply refuse to use it due to the inconvenience of connecting the contacts, which are recessed deep into the battery itself. It is undesirable to solder them, so it was decided to use the method proposed by these, namely, make a contact block yourself from an office eraser and copper wire (1.5 mm thick).First, I pierced a piece of eraser with two wires with pre-stripped ends, and adjusted them to the battery contacts so that the distance between them coincided,
I bent the ends, tinned them with a soldering iron, and pulled them back slightly by the long ends so that the resulting contacts were recessed into the eraser.
Trying on a battery: 
You can secure the contact block with a rubber band or wrap it with blue electrical tape, which is what I did in the end. 
Assembly.
The main part of the work is done, all that remains is to assemble and record it.I put a piece of foam rubber between the battery and the board so that it would not move inside the case later. I additionally soldered a 2200 µF capacitor to power the module.
When charging is connected: 
Frame. External terminal block.
The case was available on the local radio market for about $1.5, if converted into dollars, measuring 95x60x25mm, almost the size of a pack of cigarettes. I drilled several holes in it. First, for the 4-pin terminal block, taken from a non-working dimmer.I completely freed the two outer contacts from the bolts with spacers, drilled holes for longer bolts, which will hold the entire terminal block on the body. On the case itself, of course, the two outer holes will be large, and the two in the middle will be smaller - they will have contacts threaded through them, one of which is connected to VCC Pro Mini, and the second contact to pin 2.
Drilling holes, although a simple task at first glance, is still no less labor-intensive, it is very easy to miss, so I did it first with a drill of a smaller diameter, then with a larger one. 
For the tact button, I chose a cap with a slightly concave top, so that it would be easy to reach with a match or paper clip through the narrow hole in the case. 
Board in a case with a connected USB-TTL converter cable: 
About the antenna.
The antenna, as you may have noticed throughout the review, was constantly changing as I experimented with different homemade antennas. Initially, there was a round coaxial connector on the module board, but the fifth time it was used for an external antenna, it simply fell apart, so keep in mind that it is flimsy. As a result, I tore out the antenna on the PCB from the old router, and soldered it to the module board, because... it catches the net a little better than spring and wire. 
Well, completely assembled with the charging connected it looks like this: 
Test. How it works:
In addition to tests with antennas, I checked how the alarm would behave outside, in -15 frost. To do this, I simply placed the entire insides in a container and left it on the balcony overnight, the alarm did not start, the reason turned out to be generally obvious - lithium does not like frost. This was confirmed by another test, where I left the battery at home, and took the board outside through long wires and left it like that for a day in the same frost - it worked as if nothing had happened. On the other hand, it would be strange if the alarm did not work because... In the datasheets for Atmega, for modules, and for quartz, the permissible operating temperatures are up to -40 degrees.
The principle of operation is organized using an external interrupt, initially pin 2 is closed to VCC and thus logical 1 is maintained at the pin, and the controller is asleep. As soon as the contact is broken and 0 appears on pin 2, the microcontroller wakes up, lowers the 3rd pin (to which the BOOT of the modem is connected through a resistor) to ground - the module starts, the MK periodically polls the module for readiness, and as soon as it catches the network, it immediately sends call to the owner's phone number specified in the code. After rejecting the call, the device turns off without sending any more endless calls, which is the problem with many Chinese alarms.
Additional Information
#include
Circuit diagram (without charge-discharge control board) 
Conclusions and thoughts. Plans.
The alarm is used at the dacha, I am satisfied with the work, however, with further study of the AVR, more and more ideas come up for further modification. Arduino with its pseudo-language Wiring really upset me, because... One unpleasant moment was discovered in the work. When I used the port functions digitalWrite(); or pinMode(); - for some reason the GSM module froze very often. But it was worth replacing them with tricks like DDRB|=(1<On energy saving...
The assembled device worked for four full months without recharging and continues to work, although it would be more correct to say “sleep.” This can be checked by simply rebooting via the white button. With a power consumption of 250 μA (through the LE33 stabilizer) and a battery of ~1430 mAh, although okay, due to the newness of the battery, let’s round it up to 1000 mAh, it turns out that the device can sleep for about 5.5 months without recharging. If you still remove the stabilizer, then the operating time can be safely multiplied by 10 times. But in my case there is no need for this, because you still need to spend the balance from the SIM card once every three months, at the same time the device can be checked and recharged.
The example of energy saving given in the review is far from the limit, because judging by the information from the datasheet, you can lower the clock frequency of the microcontroller (and this is done by installing fuses) to 1 MHz and, if you apply 1.8 V voltage, the consumption will drop below the 1 μA bar in active mode. Very nice! But if the MK is clocked from the internal RC oscillator, then another problem will appear - the UART air will be clogged with garbage and errors, especially if the controller is heated or cooled.
Upon completion...
1)
An ordinary wire installed to break is not very convenient, I plan to experiment with a Hall sensor and a reed switch, although they say about the latter that it is not very reliable, because the contacts inside it can stick.
2)
It would be nice to add the ability to change the “owner number” without the participation of a computer and flashing it. You will have to work with the EEPROM.
3)
Try interruptions from the watchdog timer, but not just for the sake of curiosity, but so that the microcontroller periodically wakes up on its own, measures the battery voltage and sends the resulting value via SMS to be aware of how low the battery is.
4)
A solar panel can completely eliminate the need to recharge the device; this will be especially true for low-capacity batteries.
5)
For a long time I wanted to buy LiFePo4 batteries, which, according to reviews, can withstand frost well, but while I was looking for a suitable lot, spring had already quietly arrived.
6)
Work on the aesthetic component
Which Pro Mini should you buy?
If you don’t have a hair dryer, then Pro Mini “RobotDyn” Atmega168PA 3.3V, pick off the LED with something sharp and you have ~250 µA.
If you have a hair dryer, then any board, solder the stabilizer and the LED for power supply - you get ~20 µA of current consumption.
That's all for now, I hope the review was interesting and useful.
Planning to buy +174 Add to favorites I liked the review +143 +278Hello everyone, today we will look at a device called a motion sensor. Many of us have heard about this thing, some have even dealt with this device. What is a motion sensor? Let's try to figure it out, so:
Motion sensor or displacement sensor - a device (device) that detects the movement of any objects. Very often these devices are used in security, alarm and monitoring systems. There are a great many forms of factors of these sensors, but we will consider the motion sensor module for connection to boards Arduino,and specifically from the company RobotDyn. Why this company? I don’t want to advertise this store and its products, but it was the products of this store that were chosen as laboratory samples due to the high-quality presentation of their products to the end consumer. So, we meet - motion sensor(PIR Sensor) from RobotDyn:
These sensors are small in size, consume little power and are easy to use. In addition, RobotDyn motion sensors also have silk-screened contacts, this is of course a small thing, but very pleasant. Well, those who use the same sensors, but only from other companies, should not worry - they all have the same functionality, and even if the contacts are not marked, the pinout of such sensors is easy to find on the Internet.
Main technical characteristics of the motion sensor (PIR Sensor):
Sensor operating area: from 3 to 7 meters
Tracking angle: up to 110 o
Operating voltage: 4.5...6 Volts
Current consumption: up to 50 µA
Note: The standard functionality of the sensor can be expanded by connecting a light sensor to the IN and GND pins, and then the motion sensor will only work in the dark.
Initializing the device.
When turned on, the sensor takes almost a minute to initialize. During this period, the sensor may give false signals; this should be taken into account when programming a microcontroller with a sensor connected to it, or in actuator circuits if the connection is made without using a microcontroller.
Detection angle and area.
The detection(tracking) angle is 110 degrees, the detection distance range is from 3 to 7 meters, the illustration below shows it all:
Adjustment of sensitivity (detection distance) and time delay.
The table below shows the main adjustments of the motion sensor; on the left there is a time delay regulator, respectively, in the left column there is a description of the possible settings. The right column describes the detection distance adjustments.
Sensor connection:
- PIR Sensor - Arduino Nano
- PIR Sensor - Arduino Nano
- PIR Sensor - Arduino Nano
- PIR Sensor - for light sensor
- PIR Sensor - for light sensor
A typical connection diagram is shown in the diagram below; in our case, the sensor is shown conventionally from the rear side and connected to the Arduino Nano board.
Sketch demonstrating the operation of the motion sensor (we use the program):
/* * PIR Sensor -> Arduino Nano * PIR Sensor -> Arduino Nano * PIR Sensor -> Arduino Nano */ void setup() ( //Establish a connection to the port monitor Serial.begin(9600); ) void loop() ( //Read the threshold value from port A0 //usually it is higher than 500 if there is a signal if(analogRead(A0) > 500) ( //Signal from the motion sensor Serial.println("There is movement!!!"); ) else ( / /No signal Serial.println("Everything is quiet..."); ) )
The sketch is a common test of the operation of the motion sensor; it has many disadvantages, such as:
- Possible false alarms, the sensor requires self-initialization within one minute.
- Rigid binding to the port monitor, no output actuators (relay, siren, LED indicator)
- The signal time at the sensor output is too short; when motion is detected, it is necessary to programmatically delay the signal for a longer period of time.
By complicating the circuit and expanding the functionality of the sensor, you can avoid the above-described disadvantages. To do this, you will need to supplement the circuit with a relay module and connect a regular 220-volt lamp through this module. The relay module itself will be connected to pin 3 on the Arduino Nano board. So the schematic diagram:
Now it's time to slightly improve the sketch that tested the motion sensor. It is in the sketch that a delay in turning off the relay will be implemented, since the motion sensor itself has too short a signal time at the output when triggered. The program implements a 10-second delay when the sensor is triggered. If desired, this time can be increased or decreased by changing the value of the variable DelayValue. Below is a sketch and video of the entire assembled circuit in action:
/* * PIR Sensor -> Arduino Nano * PIR Sensor -> Arduino Nano * PIR Sensor -> Arduino Nano * Relay Module -> Arduino Nano */ //relout - pin (output signal) for the relay module const int relout = 3; //prevMillis - variable for storing the time of the previous program scanning cycle //interval - time interval for counting seconds before turning off the relay unsigned long prevMillis = 0; int interval = 1000; //DelayValue - the period during which the relay is kept in the on state int DelayValue = 10; //initSecond - Initialization loop iteration variable int initSecond = 60; //countDelayOff - time interval counter static int countDelayOff = 0; //trigger - motion sensor trigger flag static bool trigger = false; void setup() ( //Standard procedure for initializing the port to which the relay module is connected //IMPORTANT!!! - in order for the relay module to remain in the initially off state //and not trigger during initialization, you need to write //the value HIGH to the input/output port , this will avoid false “clicking”, and will //preserve the state of the relay as it was before the entire circuit was put into operation pinMode(relout, OUTPUT); digitalWrite(relout, HIGH); //Everything is simple here - we wait until 60 ends cycles (initSecond variable) //lasting 1 second, during which time the sensor “self-initializes” for(int i = 0; i< initSecond; i ++) { delay(1000); } } void loop() { //Считать значение с аналогового порта А0 //Если значение выше 500 if(analogRead(A0) >500) ( //Set the motion sensor trigger flag if(!trigger) ( trigger = true; ) ) //While the motion sensor trigger flag is set while(trigger) ( //Execute the following instructions //Save in the currMillis variable //the value of milliseconds elapsed since the start //of program execution unsigned long currMillis = millis(); //Compare with the previous value of milliseconds //if the difference is greater than the specified interval, then: if(currMillis - prevMillis > interval) ( //Save the current value of milliseconds to a variable prevMillis prevMillis = currMillis; //Check the delay counter by comparing it with the value of the period //during which the relay should be kept in the ON state if(countDelayOff >= DelayValue) ( //If the value is equal, then: //reset the sensor activation flag movement trigger = false; //Reset the delay counter countDelayOff = 0; //Turn off the relay digitalWrite(relout, HIGH); //Abort the cycle break; ) else ( //If the value is still less, then //Increment the delay counter by one countDelayOff++; //Keep the relay in the on state digitalWrite(relout, LOW); ) ) ) )
The program contains the following structure:
unsigned long prevMillis = 0;
int interval = 1000;
...
unsigned long currMillis = millis();
if(currMillis - prevMillis > interval)
{
prevMillis = currMillis;
....
// Our operations are enclosed in the body of the structure
....
}
To clarify, it was decided to comment separately on this design. So, this design allows you to perform a parallel task in the program. The body of the structure operates approximately once per second, this is facilitated by the variable interval. First, the variable currMillis the value returned when calling the function is assigned millis(). Function millis() returns the number of milliseconds that have passed since the beginning of the program. If the difference currMillis - prevMillis greater than the value of the variable interval then this means that more than a second has already passed since the start of the program execution, and you need to save the value of the variable currMillis into a variable prevMillis then perform the operations contained in the body of the structure. If the difference currMillis - prevMillis less than the variable value interval, then a second has not yet passed between program scanning cycles, and the operations contained in the body of the structure are skipped.
Well, at the end of the article, a video from the author:
Please enable javascript for comments to work.
GSM alarm system on Arduino
In this article you will learn how to (buy) make a GSM alarm yourself using a GSM module and Arduino very cheaply. A cottage, house, garage, apartment is ideal for GSM alarm protection.
Step 1: Elements
For this project you will need:
GSM Shield
Buzzer
Alarm siren 12V
12V power supply
Keyboard for Arduino
Frame.
Step 2: Connecting Components 
First you will place the GSM module on the Arduino Uno, you will need to solder the GND and VCC wires along with two sensors, a buzzer and a relay module input. After that, connect these soldered wires to the corresponding connector of the GSM shield. Next you will make an I/O signal connector from these parts, and the last thing you will need to do is connect the keyboard
Arduino Uno/GSM Terminals:
Pin 0: not connected;
Conclusion 1: not related;
Pin 2: unconnected (GSM will use this pin);
Pin 3: unconnected (GSM will use this pin);
Pin 4: last line using keyboard (keyboard pin 4 - from 8);
Conclusion 5: unrelated;
Pin 6: second column via keyboard (keyboard pin 6 - from 8);
Output 7: third column from the keyboard (finger keyboard 7 - from 8);
Pin 8: unconnected (GSM will use this pin);
Pin 9: unconnected (GSM will use this pin);
Pin 10: PIR sensor data No. 2;
Pin 11: siren sound signal (entered at the input of the relay module);
Pin 12: PIR sensor data No. 1;
Pin 13: buzzer input signal;
As you can see, although the keyboard has 8 pins, only three are connected (one row and two columns, allowing two numbers to be read - a 1×2 matrix), so I can make passwords using these three wires and there is no need to use all contacts from the keyboard. This is because once the motion sensor detects a person walking in the room, the person will only have 5 seconds to turn off the alarm. After the alarm is not turned off at a given time, the GSM shield sends an SMS to you, or calls your phone number. The Arduino has been programmed to make a call and as soon as you answer the phone it will hang up.
Of course, it is possible to get false readings from the sensor, so there is an option to turn off the alarm by simply sending an SMS from your phone to the Arduino. Additionally, another option that you can do is to set the shield to send you one message per day so that you know that it is working correctly.
Step 3: Code
Just download the code below and compile. It uses the Keypad.h and GSM.h libraries.
Download file: (downloads: 181)
Download file: (downloads: 104)
Step 4: Conclusion
Given that the Arduino Uno code will text and call your phone in just five seconds after someone breaks into your home, I'm guessing you'll have plenty of time to call the police. Of course, the siren will scare away thieves and your home or other premises will become safer with the help of this article.
Infrared (IR) sensors are typically used to measure distances, but they can also be used to detect objects. By connecting several IR sensors to Arduino, we can create a security alarm.
Review
Infrared (IR) sensors are typically used to measure distances, but they can also be used to detect objects. IR sensors consist of an infrared transmitter and an infrared receiver. The transmitter emits pulses of infrared radiation while the receiver detects any reflections. If the receiver detects a reflection, it means that there is some object at some distance in front of the sensor. If there is no reflection, there is no object.
The IR sensor we will use in this project detects reflection within a specific range. These sensors have a small linear charge-coupled device (CCD) that detects the angle at which IR light returns to the sensor. As shown in the figure below, the sensor transmits an infrared pulse into space, and when an object appears in front of the sensor, the pulse is reflected back to the sensor at an angle proportional to the distance between the object and the sensor. The sensor receiver detects and outputs the angle, and using this value you can calculate the distance.
By connecting a couple of IR sensors to the Arduino, we can make a simple security alarm. We will install sensors on the door frame and by aligning the sensors correctly we will be able to detect when someone walks through the door. When this happens, the output of the IR sensor will change and we will detect this change by continuously reading the output of the sensors using Arduino. In this example, we know that an object is passing through the door when the IR sensor output reading exceeds 400. When this happens, the Arduino will trigger an alarm. To reset the alarm, the user can press a button.
Accessories
- 2 x IR distance sensor;
- 1 x Arduino Mega 2560;
- 1 x buzzer;
- 1 x button;
- 1 x 470 Ohm resistor;
- 1 x NPN transistor;
- jumpers.
Connection diagram
The diagram for this project is shown in the figure below. The outputs of the two IR sensors are connected to pins A0 and A1. The other two pins are connected to the 5V and GND pins. The 12-volt buzzer is connected to pin 3 via a transistor, and the button used to silence the alarm is connected to pin 4.
The photo below shows how we glued the sensors to a door frame for this experiment. Of course, if you were using it regularly, you would install the sensors differently.
Installation
- Connect the 5V and GND pins of the Arduino board to the power and GND pins of the sensors. You can also supply them with external power.
- Connect the output pins of the sensors to pins A0 and A1 of the Arduino board.
- Connect pin 3 of the Arduino to the base of the transistor via a 1k ohm resistor.
- Apply 12V to the collector of the transistor.
- Connect the positive lead of the 12-volt buzzer to the emitter and the negative lead to the ground bus.
- Connect pin 4 to pin 5V via a button. For safety reasons, in order to avoid large current flow, it is always better to do this through an additional small resistor.
- Connect the Arduino board to your computer via USB cable and load the program into the microcontroller using the Arduino IDE.
- Power the Arduino board using a power supply, battery, or USB cable/
Code
const int buzzer=3; // pin 3 is the output to the buzzer const int pushbutton=4; // pin 4 is the input for the button void setup() ( pinMode(buzzer,OUTPUT); // set pin 3 to output pinMode(pushbutton,INPUT); // set pin 4 to input ) void loop() ( // read the output of both sensors and compare the result with the threshold value int sensor1_value = analogRead(A0); int sensor2_value = analogRead(A1); if (sensor1_value > 400 || sensor2_value > 400) ( while(true) ( digitalWrite(buzzer,HIGH) ; // turn on the alarm if(digitalRead(pushbutton) == HIGH) break; ) ) else ( digitalWrite(buzzer,LOW); // turn off the alarm ) )Video
