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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Pairing a security and fire device with a cell phone. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Safety and security The proposed prefix serves as an addition to the Quartz fire and security control panel (PPKOP), allowing you to automatically transmit an alarm signal by cell phone. It is easy to repeat and contains only the minimum required number of parts. The set-top box not only calls in case of an alarm at the number stored in the phone's memory in advance, but also receives incoming calls, allowing you to remotely "listen" to the protected object at any time. It automatically recognizes whether the Control Panel is armed by monitoring the loop (or sensor circuit) for opening and closing, and also monitors the health and condition of the cell phone. This cannot be provided by simple signaling devices, the descriptions of which were published earlier. If necessary, the set-top box can be used as an autonomous security device without connecting it to the control panel. Almost any cell phone can work with it. The author used the device model Motorola C115. The number of the subscriber of the telephone network, which will be notified about the switching of the system to the armed mode and about the alarm, is entered in advance in the list of outgoing phone calls. When receiving an incoming call, there is no automatic hang-up, it must be given by the caller himself.
The attachment diagram is shown in fig. 1. Its basis is an eight-output microcontroller PIC12F683 (DD1) with a program that analyzes the state of the relay RC1 of the control panel and controls a cell phone. After turning on the power, the program first of all checks whether the Control Panel is in the "Security" mode. A sign of this mode is that the closed contacts of the relay PTsN1 at the input GP2 of the microcontroller set a low logic level. The phone status signal is taken from its "Call" button and through the inverter on the transistor VT1 is fed to the input GP3 of the microcontroller. Based on the logic level of the signal coming to this input, the program checks whether the cell phone is on (low level) or off (high level). If it is off, the program sets the GP3 output high for 4 seconds. As a result, current flows through the emitting diode of optocoupler U1.1 and its phototransistor opens, simulating pressing the "On / Off" button for the specified duration. phone. The program then checks to see if the phone is turned on. If not, a new attempt is made to turn it on, up to five attempts in total. After making sure that the phone is turned on, the program generates two high-level pulses one after the other at the GP4 output, simulating a double short press on the "On / Off" button. This cancels all received incoming calls and SMS messages. Then the dialing of the number previously stored in the phone's memory is performed. To do this, the program generates two high-level pulses at the output of GP5. With the help of the U1.2 optocoupler, they imitate two presses on the "Call" button of the phone. The first opens a list of outgoing calls in it, the second initiates a call to the number dialed last. After 50 seconds, which is enough for the person who turned on the alarm to leave the protected premises, the set-top box switches to the "Protection" mode. In this mode, it is periodically checked whether the set-top box is supplied with a voltage of 5 V from an external mains power source. If not, the program turns off the phone, thereby extending the life of the GB1 battery. It will only turn on when an alarm is needed. Incoming calls cannot be received in this state. When there is mains power, the phone remains on. The program also turns it on when the power supply is restored. If you want the phone not to turn off in the absence of mains power, you should remove the VD3 diode and connect the upper output of the resistor R4 to the + and power circuit. Next, the program checks to see if the phone is currently receiving an incoming call. To do this, the signal intended for vibrating the phone is applied (after being formed by the transistor VT2) to the line of the GP0 port operating in the input mode. During a call, the impulses here are repeated several times for ten or more seconds. And if you receive an SMS message after 10 seconds, they will no longer be there. This allows the program to distinguish between calls that should be answered by "picking up the phone" and messages that should not be answered. False positives are possible if several messages begin to arrive at short intervals one after another for more than 10 s, which is unlikely. While the control panel remains in the "Arm" mode without giving an alarm signal, the checks for the presence of the supply voltage and the incoming call are repeated cyclically. Having detected the transition of the control panel to the "Alarm" mode (opening of the contacts of its relay of the monitoring station1), the program checks whether the phone is turned on, and if not, turns it on. A pause of 50 s is maintained. It is required for the phone to perform the power-on and network registration procedures. After that (and if the phone was turned on at the moment of switching to the "Alarm" mode, then after a pause of 10 seconds), outgoing calls begin. Each one lasts 30...40 s depending on the connection time. Then the program hangs up and, after a pause of 15...20 s, repeats the call. As practice shows, the five-time repetition of calls provided for by the program is quite enough for reliable notification of an alarm. The prefix can be connected not only to the contacts of the CCN1 relay, but also to the control lamp of the control panel, which is constantly on in the "Security" mode, and flashes at a frequency of 1 Hz in case of an alarm. If the lamp is powered by a constant voltage of 12 V, the attachment is connected according to the circuit shown in fig. 2. For a test lamp powered by a 220 V network, the circuit will have to be complicated by adding a diode bridge to rectify the alternating voltage. The resistance of the resistor R11 in this case must be increased to 24 ... 36 kOhm, and its power - up to 2 W and a capacitor with a capacity of several microfarads should be installed in parallel with the emitting diode of the optocoupler. If there is no control panel in the security system, a wired loop or the contacts of the security sensor closed in the absence of an alarm are connected directly to the console instead of the contacts of the relay of the monitoring station1. The phone will call the specified number if the loop breaks or the sensor contacts open. If, after making five calls, the integrity of the loop is restored, the set-top box will automatically return to standby mode. Preparing the phone to work with the set-top box, it turns off the sound of pressing the keys, receiving SMS messages and incoming calls. Only the vibrating alert should remain on. After removing the vibrating alert motor, the wires going to it are connected to the set-top box, and the negative wire serves as a common one. The phototransistors of the dual optocoupler U1 are connected to the positive contacts of the phone buttons indicated in the diagram, having previously determined the voltage polarity between their contacts with a multimeter. The supply voltage +4,3 V (circuit + ip in Fig. 1) is applied to the contact of the telephone, to which the positive terminal of its battery was connected. The battery itself is removed. If the phone does not turn off and turn on at the command of the set-top box, the program switches the GP0 output of the microcontroller to the output mode and starts generating 2,5 kHz pulses on it. Piezo emitter HA1 gives a sound signal. In the absence of +5 V, the audio signal will be intermittent.
The signal means that the GB1 battery is probably dead and needs to be replaced. Before replacing, be sure to turn off the +5 V voltage (if it was on) and only then change the battery, otherwise the sound signal will remain on. I would like to draw your attention to the fact that the state of the GB1 battery is not actually controlled and its discharge is only the most likely reason for the phone not responding to the commands given by the set-top box. The device uses resistors C2-23, MNT, the oxide capacitor is imported, the rest of the capacitors are ceramic K10-17. Transistors KT3102BM can be replaced with any of the series KT315, KT3102. Diodes VD2, VD3 - any silicon for a current of at least 1 A. Diode VD1 - with a small forward voltage drop (germanium or Schottky diode) and a permissible forward current of at least 1 A. The ZP-Z piezoelectric radiator can be replaced with ZP-5 or another without built-in generator. You can power the set-top box from any mains stabilized DC voltage source of 5 V. The GB1 battery consists of three alkaline galvanic cells of size AA (LR6). The set-top box microcontroller program, as well as the block diagram of this program, can be downloaded from ftp://ftp.radio.ru/pub/2012/10/gsm.zip. Author: A.Kovtun
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