This article will be useful to anyone who is interested in the smooth operation of a computer, turning it on remotely, in managing both a computer and other devices, for example, a car engine, a greenhouse. You can organize watering indoor plants without the direct presence of a person. Other possible applications will be described below. Switching on / off is carried out "on call" and, most importantly, for free.

Main technical characteristics:
Number of control combinations - 2 (when finalized - more);
Supply voltage - 5V;
Number of relay outputs - 4 (max 100V/0.5A);
Range - limited by the coverage area of ​​the cellular network.

Schematic diagram of UUU GSM "On call"

Circuit diagram description

The basis of the device is one of the most "budget" microcontrollers of the company - Tiny13A. This controller uses absolutely all 8 pins. Moreover, pin 1 is used as a RESET for sequential programming. Pin 2 (PORTB3) is set to input. This output receives an optically isolated signal from the cell phone speaker. The speaker itself should be soldered. The green LED VD1 informs about the status at pin 2 of the microcontroller. Relays are connected to terminals 3,7,6,5, shunted by diodes VD6 ... VD9 to protect the outputs of the microcontroller. In parallel with the relay, red LEDs are connected through resistors, signaling the status of the outputs.

5V power is supposed to be taken from the phone charger, since many phones are now charged from USB. If there is a higher voltage, you should install a stabilizer, for example, LM7805.

Relays consume current of about 10mA, so it was decided to connect them directly to the microcontroller pins.

UUU GSM "On call" is used to turn on the computer, so the output assignments are as follows:
1. XT3 - RESET PC - connect to the RST pins on the motherboard;
2. XT4 - parallel to the CTRL key on the keyboard (for what - I will explain below);
3. XT5 - parallel to the F1 key on the keyboard;
4. XT6 - ROWER ON - connect to the PW pins on the motherboard.

Initially, it was supposed to connect this device to the keyboard. Therefore, it was decided to output channels 2 and 3 separately. In the BIOS, at the same time, it is necessary to make the computer turn on using the CTRL + F1 keys active. Channels 2 and 3 simulate pressing this particular combination.

Radio elements used in the circuit

The basis, as mentioned above, is the Tiny13A microcontroller. With a corresponding change in the firmware and circuit, it is possible to replace it with any other, since Tiny13A has the smallest functionality. Optocoupler - common 4N35. It is possible to replace it with a similar one with an output current of at least 20mA. All resistors are applied with a power dissipation of 0.25W. Their denomination is indicated on the circuit diagram of the device. You can use any LED with a diameter of 5mm. Relay -SIP-1A05. You can use similar coils with a current of not more than 15-20mA and a voltage of 5VDC. Terminal blocks - DG301-5.0-02P-12 or similar.

Description of software and firmware

Initially, there was an option to use services like DynDNS. But this option was quickly rejected for several reasons: some services are paid and require a wired network connection. The latter is due to the fact that at the moment many computers do not have the Wake on USB function. My development is not limited by the coverage of the Wi-Fi network and, moreover, the Internet (meaning enable / disable. Controlling a computer, for example, from a phone, requires an Internet connection).

The versatility of this method of remote load control lies in the fact that you can use absolutely any phone that can play MP3.

Also, this design is possible development. With the same success, you can control not only a computer, laptop, but also, for example, an irrigation device in a garden or at home, open and close doors and windows in a greenhouse, start a car engine, shut off water, gas in the country and at home. You can turn on the preheating of the bath, which uses electric heaters.

By turning on a computer with this device when the computer has Internet access, the versatility and scope of the device "On Call" are significantly increased. Namely, with the help of specialized software and in the presence of a Wi-Fi network, you can organize wireless video surveillance "On call". By installing IP video cameras, you can monitor the monitored object at the right time. After checking, you can turn off the computer both "by call" and via the Internet using specialized software.

Connecting a load control device (for example, Master KIT) to the USB port of a computer and simultaneously connecting to a remote desktop significantly expands the list of dial-up channels.

There is also the possibility of a multifaceted increase in the number of control channels. Let's highlight two of them:

1. By adding other numbers. This method involves creating new MP3 "melodies" for the phone and installing them on certain numbers. After these manipulations, it is necessary to debug the control 32-bit packet for new numbers in the controller. (see debugging a 32-bit control package). This method does not require a computer. All you need is a phone that supports MP3. Surely every radio amateur has a box of old cell phones. The advantages of this option are simplicity of design, minimum costs. Today, not everyone wants to install a computer in the country. This is not only dangerous, but also entails an increase in the cost of the product.

2. Application of USB load control device for computer. To use this option, in addition to the main equipment, you will need the following devices: a computer (laptop), a USB load control device, a USB modem for connecting to the Internet. Here the possibilities are endless. This includes security, remote control, and monitoring.

The project in the CodeVisionAVR programming environment can be found in the attached archive. At the very beginning of the firmware, you can see the same control 32-bit packages. This program is debugged and does not require intervention. The next step is to initialize the microcontroller. In an endless while loop, we expect the appearance of a logical “0” on pin 2 of the microcontroller. As soon as it appeared, the variable is filled. After filling 32 bits, we impose a mask on this variable. If equal to any value, the corresponding action is performed. The steps to be taken have been described above. I will add that when it matches the first control 32-bit packet, the following happens: we simulate pressing the Ctrl key, we simulate pressing the F1 key, and release it. Then we simulate pressing the power button on the computer. As you can see, you can use any of the proposed options.

If the control packet coincides with the second one, pressing the Reset button on the computer's system unit is simulated. This function will be necessary when using old computers, where there is a high probability of freezing, which can be determined by the same specialized software, and there are a lot of them now.

Fuse programming

Below are the fuses for the programming environment:
LOW
SPIEN jackdaw
EESAVE no
WDTON jackdaw
CKDIV8 no
SUT1 checkbox
sut0 No
CKSEL1 checkbox
CKSEL0 no
HIGH
SELFPRGEN no
no DWEN
BODLEVEL1 no
BODLEVEL0 no
no RSTDISBL

Device setup

The whole setup comes down to debugging a control 32-bit package.

I have identified two main methods:

1. Modeling in Proteus. This method is attractive in that it is possible to detect errors at the development stage, and not at the assembly stage. This method did not bring a positive result in the end, but helped to cope with minor shortcomings. The firmware created according to the timing diagrams worked perfectly in Proteus, but refused in the hardware. I created additional debug firmware for the second controller of the same type for simulation in . The optional Tiny13 controller simulated MP3 tunes depending on the button pressed. When pressing the *** button, a call from SIM1 was simulated (for simplicity of presentation of the material, I will call the numbers SIM1 and SIM2. The project was made for 2 combinations). Accordingly, when you press the *** button - a call from SIM2. The archive contains Proteus files.

2. The second way is very original. To debug the device, you will need a video camera or a camera with the ability to record video. The debug firmware of the controller was created. The essence of debugging is to calculate a valid 32-bit control packet, because, as it was written above, the program debugged in Proteus refused to work in hardware. The program algorithm is such that with each read value of the logical "1" relay K1 changes its state to the opposite. This is indicated by the red LED VD2. Similarly, when reading the logical "0" relay K2 changes its state to the opposite, indicating this LED VD3. The procedure is the following. Download the attached "MP3 ringtones" to your phone. We set the first one to a call from SIM1, the second - to SIM2. We put on a video recorder. We supply power to the circuit. We call sequentially first from SIM1, then from SIM2. We throw off the recorded video on the computer and play it slowly. In parallel, we analyze the operation of the LEDs and write the resulting logical value into a pre-prepared table. If read correctly, two 32-bit control packets should be obtained. These values ​​should be written at the beginning of the program. Next, flash the controller with the resulting compiled firmware and install it on the board. In the attached archive, you can find already debugged firmware, which is written for MP3 "melodies" attached in the same archive. As a result, control 32-bit packets were calculated in such an original way.

The figure below shows the timing charts of MP3 "melodies"

Printed circuit board

The printed circuit board in dip and pdf formats can be found in the archive. Below is a screenshot of the printed circuit board, which is made on a one-sided foil-coated fiberglass using the LUT method.

The total cost of the device

ATtiny13A - 28 rubles;
4 relays - 150 rubles;
2 screw clamps - 5 rubles;
Optocoupler 4N35 - 9 rubles;
Capacitor - 5 rubles;
LEDs 6 pcs. (the power LED is not shown in the diagram, it is on the board) - 6 rubles;
Diodes 1N4007 - 4 rubles;
Resistors 5 rubles;
Connectors "Tulip" - 15 rubles;
Connector DRB-9MA - 13 rubles;
Chinese phone - 300 rubles;
Printed circuit board - 40 rubles;
Housing - junction box 75x75 - 30 rubles.

Total: 610 rubles.

If you have a phone, the cost of parts is only 310 rubles!

Photo of the assembled device:

List of radio elements

Designation	Type	Denomination	Quantity	Note	Score	My notepad
	MK AVR 8-bit	ATtiny13A	1			To notepad
	optocoupler	4N35M	1			To notepad
VD1-VD5	Light-emitting diode		5			To notepad
VD6-VD9	rectifier diode	1N4148	4			To notepad
C1	electrolytic capacitor	1000uF 16V	1			To notepad
R1	Resistor	300 ohm	1			To notepad
R2	Resistor	390 ohm	1

Special offer for objects with a large number of regular users (business centers, summer cottages, corporate parking lots, car depots).

Control of gates/barriers via GSM-channel.

Let's say you have a territory that can be reached through a barrier. You need to organize the entry of a large number of cars into this territory. To do this, you will need the barrier itself (which you can, of course, purchase from us) and some control system for it.

Let's take 200 cars for clarity - a normal number for an average business center. That is, you will have to pay several times more for one remote control than for equipping the checkpoint with a barrier. This means that we will have to resort to unpopular measures to extract money from people, which, as you know, are never superfluous, then distribute remote controls to everyone and everyone individually, which will naturally delay the process of automating the entrance.

But there is another way. Technology does not stand still, and a few years ago it became possible to control automation from a mobile phone, which everyone has today. After installing and configuring the special GSM-unit ESIM110 or ESIM120 (NEW) you can simply call the phone number of the SIM card installed in the unit, and the entrance will be opened. The setting consists in filling the block database with user phone numbers. If the number of the call coming to the block matches one of the numbers in the database, the gate opens. The call is completely free, because. the block immediately "resets" it.

For 200 cars, the savings are 180 thousand, which, you see, is quite good.

Oh yes! Even at the entrance you will need to hang a printed memo on which number to call to enter. :)

Control unit ESIM120

Recently, an improved version of the ESIM110 block went on sale - ESIM120, in addition to all the functions of its predecessor, having a number of modern features:

• Additional relay output (possibility to connect two devices at once)
• Open/close and turn on/off with the touch of a button on the smartphone app
• SMS-notification about the breakdown of the gate or other connected automation
• User classification for access restriction and control
• Limit on the number of users: 1000 (versus 500 for ESIM110)
• Compatibility with ELDES cloud server

A story about the ESIM110/120 system in a short video from the manufacturer:

SN automation is a pioneer in Russia in the field of gate control via a GSM channel. We have managed to gain a fairly extensive experience in using these modules, and for many of our customers the system has proven itself to be excellent for its reliable, efficient operation, ease of configuration and significant savings. Feel free to recommend to enterprises, homeowners associations, dacha cooperatives and other organizations interested in saving and having from 10 subscribers. ()

The GSM-module allows you to remotely control any automation, receiving a signal from a telephone operating in the GSM range, and turning on / off the connected equipment. It is used to open swing and sliding gates, barriers in parking lots, parking lots, summer cottages and garage cooperatives, private houses, remote control of engineering systems for irrigation, lighting, heating, rebooting servers and routers.

This is how the owner opens the gate at the entrance to the territory

The GSM-module is most widely used as a reliable and low-cost controller for managing group access to an object, compatible with the popular automation of gates and barriers Doorhan and Came.

How the module works

In essence, a GSM module is a radio receiver with an installed sim card of any mobile operator and a controller for processing incoming and outgoing information. The module database contains the phone numbers of all users who have the right to access the closed area. Modern models support recording and storing up to 2000 numbers, more expensive modifications can process up to 10,000 numbers.

The principle of operation of the device is shown in the figure.

Schematic diagram of the device

When making a call, the controller checks the incoming number with the recorded data, and if it is in the memory, a command is given to open and actuate the barrier and sliding gate drive. If the number is not in the list, then the device simply hangs up the call without doing anything else. Similarly, the controller opens swing gates equipped with an electric lock and a Doorhan or Came drive.

There is no connection with the caller, or it is disconnected after a few seconds, due to which the cost of paying for cellular services is zero. If the data does not match, then the pass through the enclosing device is not provided. In some models, it is possible to disable identification, and the pass is carried out with any incoming call to the controller. The GSM module control unit is configured using SMS commands, a web interface, a program on a computer connected via a USB port, and an android application for smartphones.

Let's give an example of a gsm-module from Tor-House LLC. There are two models that differ in the number of user numbers and the set of functions. Photo modules in the figure below.

The technical characteristics of the modules are given in the table.

Characteristic	Model TH-G01	Model TH-G02
Power supply, V	=12 or 24 V	=9 ... 24V
Frequency, MHz	Bands 850/900/1800	Bands 850/900/1800
SIM card	Standard 1.8/3V	Standard 1.8/3V
Antenna		50 Q SMA, connection of an external antenna with SMA connector is possible
Relay	1, dry contact NO/NC	2, dry contact NO/NC
Number of users	99	3002
User registration	SMS	SMS or call
Temperature range	-30 … +60	-30 … +60

Pros and cons of gsm modules

• there is no need to purchase individual remote controls, key fobs or cards, and not all barrier control systems are “rubber” and are designed for a limited number of them;
• you can open a barrier or gate from any place included in the coverage network of a mobile operator, thanks to which it is not a problem to provide a pass for a friend to the territory, being out of reach - not a problem, + simplifying the work of the security service;
• control - using software or SMS commands, it is possible to add and remove numbers from the database, configure parameters such as admission by day of the week, time of day, entry ban in case of non-payment of mandatory fees, keeping a log of entries, etc .;
• the ability to install on automatic barriers and gates of any manufacturer;
• savings - the price of one gsm controller is approximately equal to the cost of three Came remotes, and with a large number of users, such automation of travel is much more profitable.

And a small fly in the ointment in a barrel of honey - it will be impossible to open a gate or a barrier with a dead phone battery or a zero balance, whether they are Doorhan or Came three times, but the same thing can happen if you, for example, have forgotten or lost the remote control.

Characteristics of popular models

Teltonika

A simple module that provides services to up to 500 clients. It is installed on swing gates, used to control barriers, sliding gates and other devices with electric drive.

Teltonika VRT012

Compatible with Doorhan automation, operating voltage - 12 V, equipped with a power supply for connection to a 220 V network. Works stably from -20 to + 40 ° C. The client list is set up via SMS or via a computer application.

doorhan

The controller stores up to 500 numbers in the database. Designed for installation both directly into the body of sliding gates and barriers with Doorhan automation, and outside. Operates at a temperature of -20 to +40°С, has its own housing for protection against external influences. Power supply 12-24 V.

Doorhan module

Parameters are configured by SMS commands or via a computer. The Doorhan module is compatible with other manufacturers' automations, there are only a small number of actuators that require additional adaptation. To find out about the possibility of installation, contact the specialists of the organization-seller.

ESIM 110/120

Provides access to the territory for up to 500 clients, an additional option - expansion up to 2000. In the improved version - ESIM 120, cloud management technology is implemented through the WEB interface and from a mobile application.

ESIM120 ELDES — GSM controller for opening gates and access doors

The controller is compatible with Doorhan sliding gate automation, is compact and can be built inside the drive system unit. Convenient logging, where you can set various parameters for entry permits individually for each client and see who and when drove in - a memory for 1000 events. Operating voltage 10-24 V, temperature range from -20 to +55°С.

Places of application

The modules are used to control any type of equipment with an electric drive:

• automatic gates, barriers;
• boilers;
• office doors (if there is an electric lock);
• alarms;
• cars;
• and other devices.

We are already familiar with devices such as GSM / MMS cameras (), GSM alarms () that send messages when a motion sensor is activated. These were the first devices using GSM-modules and their use began to expand.

GSM-modules are being actively implemented, they showed the greatest efficiency for control at the entrances to cottage settlements, large residential complexes, commercial facilities with a large number of staff or customers.

Let's say there are 5 houses in the residential complex "Berezka", 500 apartments are multiplied by 1500 rubles. (average key price). The HOA will have to collect 750,000 rubles from the residents. only for the purchase of keys.

It turns out a big economic benefit in comparison with the purchase of keys!

It will be easier to persuade homeowners to buy an automatic barrier when the amount of investment in equipment and installation is 2000-3000 rubles per apartment.

Compared to RFID tags, which can also be used as gate openers, RFID identification is somewhat different, the equipment kit is more expensive, but the range of application is wider.

In the next article, we will analyze the module from SmartAirkey - keyless access to the entrances and parking lots of apartment buildings.

pull March 3, 2016 at 01:35 pm

Multifunctional control device and control via GSM channel

• Microcontroller programming

Radio hobby instilled since childhood in the radio circle led in a roundabout way to programming microcontrollers and making useful crafts for home use and not only. One of these crafts was security system suburban area from "freebie lovers".

The first attempts of protection with SMS notification about the intrusion of the above-mentioned persons into the summer cottage were carried out on the Atmega8 microcontroller and Siemens-C35 telephone. But this project remained unfinished due to the ability of the selected phone to turn off at the right time.

The module has become a new toy SIM900 from Simcom. After reading the forums about this module, I was upset because 99% of the examples and explanations are offered in C, and I know and use only assembler. After a long study, this project was born.

I will be narrating from the side of a curious researcher who is starting to deal with this module (which was not enough during my own search).

GSM module

For power supply, a common DC / DC converter circuit on the LM2596 chip was used. In addition to the main function, it has the ability to turn off the consumer when a high level is applied to the control input (in the diagram, the On / Off PWR input). This function makes it possible to restart the GSM module in case of any freezing or programmable "falling asleep" of the module.

Communication with the module is carried out via the UART channel using AT commands. To start (on / off) the module, the “On / Off GSM” input is used, when a low level is applied for 2-3 seconds, the module connects to the network (after which it is necessary to set a high level, because the module will disconnect from the network if the action is repeated). When connected, a high level appears at the Status output, and the “Status” diode will blink (the blinking intervals for different stages of work are described in the datasheet).

Printed and schematic created in Eagle (download).

Control board

The control was done on the available Atmega16 microcontroller. I also tried it on the Arduino Nano V3 board (Chinese equivalent). The latter is very convenient at the development stage - take it and work.

Schematic created in Eagle Download, PCB is in the process of being perfected. Added the ability to connect RF24L01 for remote polling and control.

The controller itself performs the following functions:

1. Polling four input lines. When a break occurs, a timer is started for 5-20 seconds, if during this time the input line has not returned to its original state or the "disarm" button has not been pressed, an SMS message is sent to a predetermined number.
2. Control of four outputs via SMS message. When receiving an SMS message with a certain code, the controller turns on or off the corresponding output.
3. Status information. When requesting a status (sending an SMS with a code), it sends a response about the status of all outputs, inputs and the status of the balance.

Having seen enough that in the overwhelming range of such devices, in order to save the duty number, it is necessary to pull out the SIM card, insert it into the phone and register only in a certain cell, it was decided to simplify this action.

The activation of the duty number is carried out by a simple manipulation: by pressing the button, let's call it "RESET", we overload (turn off the mains and turn on) the device - thereby erasing the previous recorded number. Then, by pressing the same button, we dial the number of the SIM card installed in the device. By flashing us with diodes, the device will save the number of the dialer and send an SMS about the activation of this number.

To simplify the adjustment of this complex, a program was written for an android phone, for easy control of sending SMS. Site-constructor for applications.

This concludes the review first part. In the next part, I will consider the communication of the controller with the GSM module.

Tags: gsm control, sim900

GSM CONTROL AND MONITORING DEVICE

This device is designed for various control and monitoring functions using the GSM channel. For example, it can be used to control various loads, as a security system, temperature measurement in controlled areas, etc.

Functionally, the device consists of a microcontroller, a signal decoder DTMF, built-in GSM module SIM300D, pulse power supply(4.3V / 2A) and electromagnetic relays for load control.

There are 4 channels for controlling loads up to 2 kW (230V / 10A), five inputs that can be programmed for various functions. It is possible to connect a backup power source, for example, a battery Casil 1270. Four LEDs, which are placed directly on the printed circuit board, are designed to control the activity of the SIM300D module, the presence of a cellular network, the programming and connection mode, and the identification of a DTMF signal.

The option of connecting various loads and sensors to the control and monitoring device is shown in fig. one

Rice. one

The schematic diagram of the device can be downloaded from the link at the end of this article. The basis of the device is a microcontroller 16F876A. This controller has a built-in hardware USART, through which the GSM SIM300D module is controlled. The microcontroller has an external quartz resonator with a frequency of 4 MHz. The R9C5 circuit is designed to reset the microcontroller at the initial power-up moment. Transistor switches (and, accordingly, relays) are controlled through port B0-B3. The inputs of the device are implemented through the port A0-A3.

According to port pins C0-C4 a four-bit code is received from the DTMF decoder MT8870. The four-digit code is directly transmitted along lines C0-C3, and a strobe pulse is transmitted along line C4. It appears on the STD output of the decoder at the moment the DTMF signal is recognized. The identification duration is set by the R4C4 MT8870 circuit. Frequency clocking is carried out by an external quartz resonator with a frequency of 3.5795 MHz. The input signal is applied to pin 2 from the SIM300D module through the isolating circuit R1C3. Through the capacitor C12 from the output 28 of the microcontroller, the confirmation signals of the executed commands are sent to the microphone input of the GSM SIM300D module. Through pin 16 and key VT5, the GSM module is launched. The Program button is designed to enter the programming mode of service functions (password, number of calls, etc.)

GSM module SIM300D included as standard. Zener diodes VD13-VD16 protect the SIM card inputs. The VD10 LED through the VT7 transistor key indicates the state of the GSM network, and VD11, controlled by the VT6 key, indicates the status of the SIM300D module.

Considering that all elements of the device - the DTMF decoder, the microcontroller and the SIM300D module are powered from the same power source, no matching elements are required. The only point is the decoupling of the USART module of the microcontroller from the SIM300D using two resistors R18 and R19.

The power supply is built according to a combined scheme - first, the input DC voltage is stabilized at 15V using a microcircuit LM7815. The R5R6 circuit is a divider that controls the presence of input voltage through pin 7 of the microcontroller. Diodes VD2 and VD4 do not allow additional discharge of the backup battery (which is connected in parallel with capacitor C6) through the stabilizer LM7815 and in addition, limit the voltage level to 13.2V. which is designed to power electromagnetic relays. Next, the voltage is supplied to a switching stabilizer built on a microcircuit LM2576. This microcircuit is an adjustable switching regulator, the value of the output voltage depends on the ratio of the resistances R21 and R22.

The entire logic of work is controlled by a program whose code is hardwired into the microcontroller. The functionality of the device can be changed by the corresponding firmware versions. Circuitry for new versions has changed slightly. Links to descriptions of each subsequent version are provided at the end of this page.

Description of version 1.0.

Control mode.

Dial the number of the SIM card installed in the device from a cellular or landline phone operating in tone dialing mode. After passing the programmed number of calls, a two-way connection will be established, the control LED will light up and the user must enter a four-digit password. If the password is entered incorrectly, the connection is terminated. If the input is correct, the user enters the load management mode. Buttons 1-4 select the appropriate load channel. Then, by pressing the “*” symbol, the selected load is turned on. To turn off, the desired channel is again selected and the “#” symbol is pressed. When channel 5 is selected, all loads are controlled simultaneously. After finishing work, you must double-click the "#" symbol. The connection is terminated and the device returns to its original state. After the connection is established, if the time interval between the issuance of DTMF commands by the user exceeds 1 minute, the connection is automatically disconnected and the device returns to its original state.

Programming mode.

Dial the number of the SIM card installed in the device from a cellular or landline phone operating in tone dialing mode. After passing the programmed number of calls, a two-way connection will be established and the control LED will light up. Enter the previously set password. If the password is entered incorrectly, the connection will be disconnected. If the password is entered correctly, the device enters the load control mode. To enter the programming mode from this mode, press and hold the PROG button for at least 3 seconds. After the LED blinks three times, release the button and enter a new four-digit password from the phone keypad. The entry of each digit is confirmed by a beep. The fifth digit determines the number of calls before "auto pickup" - i.e. device activation. After entering the number of calls, the device exits the programming mode and the connection is terminated.

By default, in the microcontroller firmware version 1.0, the service password is programmed - 1234, the number of calls is 3

Sound signaling of executed commands:

Programming Entry Confirmation - High Frequency Double Tone

Password prompt - high frequency triple tone

Password Verification - Triple High Tone

Password Invalid - Low Frequency Triple Tone

Correct channel selection (1-5) - high frequency single tone

Wrong channel selection - single low frequency tone

Load on - high frequency double tone

Load disconnected - low frequency double tone

End of work - low frequency triple tone

ATTENTION!Read about all the improvements and new versions of the GSM control and monitoring device here:

Final version. Added audio control mode and impulse load control.

New design of the device. Ability to work with any firmware 1.0 - 1.7.

Allows you to control the presence of voltage on the loads and manual control mode.