Security device with iBUTTON key control. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Security devices and object signaling

 Comments on the article

The proposed device can perform the functions of a burglar alarm or simply turn on the lighting when a person moves in the room and when the front door is opened. Its scheme is shown in Fig.1. The basis is the PIC16F84 microcontroller. Its program provides automatic recovery of normal operation after random failures.

Fig.1. Schematic diagram of the security device

Arming and disarming is carried out using iButton DS1990 electronic tablet keys [1]. These very easy-to-use and reliable products are not afraid of moisture and aggressive environment, do not require changing or recharging batteries, as they do not contain them. The code written in the tablet cannot be changed. It has 280 trillion options, which virtually eliminates the possibility of picking a key.

The contact device X1, which must be touched with a key to turn the security on or off, is located in any convenient place, for example, on the door jamb. However, the security device itself must be inaccessible to outsiders. Wiring from it to the contact device is carried out with a twisted pair of wires no more than a few meters long.

LED HL1 is used to monitor the status of the device. It can be used to determine whether the armed mode is on, whether the alarm has been triggered for the time elapsed since it was turned on. The security loop, conventionally shown in the diagram as the SA3 switch, is the series-connected output contacts of the IR motion sensor and the SMK reed sensor installed on the door. If there is no motion sensor, the device will only react to the opening of the door.

When the power is turned on, the device starts working in a mode in which, when the loop is opened, it only turns on the lighting. After about a minute, the light will automatically turn off. To switch to armed mode, you need to touch the contact device X1 with the registered key. After reading the key code, the microcontroller prohibits re-reading for 1 s, preventing unpredictable mode changes if the key is held in the contact device for too long.

Arming will be confirmed by a short sound of the HA1 siren and a flash of the HL1 LED. But in fact, the protection will be turned on only after the closed state of the loop is restored (if the latter was open). This allows the owner to leave the premises and close the door behind him without causing a false alarm.

In the security mode, the HL1 LED is on, the lighting is off. Violation of the loop leads to the activation of the HA3 siren for 1 minutes and the blinking of the HL1 LED. Then the microcontroller checks the status of the loop again. If it is closed again, the siren will be turned off, but the LED will continue to flash. Touching the contact device again with the registered key will disarm the premises, which will be confirmed by a two-time short-term activation of the siren and the extinguishing of the LED. But any attempt to pick up the key will not change the operating mode, but will cause the siren to turn on for 1 s.

The power supply unit of the device consists of a rectifier on a diode bridge VD3-VD6 (a step-down power transformer is not shown in the diagram) and two integral stabilizers DA1 and DA2. Diodes VD3-VD8 can be replaced by any diodes with a voltage of at least 50 V and a current of 1 A. The voltage of 13,7 V is designed to power the HA1 siren and recharge the battery that supports the operation of the device when the mains is turned off. If there is no need for backup power, instead of KR142EN8E, you can install a 12 V stabilizer, and exclude diodes VD7 and VD8.

Siren HA1 - automobile UP-35, but any other piezo sirens, for example, used in security systems (OOPZ-12, "Svirel"), can also be used. The storage battery is a maintenance-free acid battery designed for fire and security alarm devices.

The device is assembled on a printed circuit board made of one-sided foil fiberglass (Fig. 2).

Fig.2. Printed circuit board

For the DD1 microcontroller, it is best to provide a panel. This will allow, if necessary, to replace or reprogram the microcontroller. The scheme of the programmer and the program for it can be found on the Internet. For example, at pic16f84.narod.ru. There is also a programming manual.

To register the key, briefly close the contacts of the SA1 "PROG" switch. As soon as the HL1 LED lights up, touch the X1 contacts with the key. Successful registration will be confirmed by the LED going out and a short siren sound. After a while, the LED will light up again - the controller is ready to register the next key. There may be seven in total. The eighth will erase data about the first, the ninth - about the second, and so on in a circle. 40 seconds after the last registration, the device will automatically return to the operating mode.

To cancel the registration of all keys, it is enough to briefly close the SA2 "ERASE" switch. The memory will be cleared and the registration mode described above will be enabled. This procedure is necessary when you turn on the device for the first time, as well as if one of the keys is lost.

The text of the program in assembler and the firmware of the controller can be downloaded here.

Publication: cxem.net

See other articles Section Security devices and object signaling.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive Ion-optical quantum microscope sees individual atoms 09.03.2021 Researchers at the University of Stuttgart have developed a new ion-optical microscope that uses quantum effects to create images of individual atoms. Note that in recent years, scientists have created many variants of the so-called gas quantum microscopes, but their resolution allows you to consider objects with a size of about 0,5 micrometers. This is enough to be able to consider isolated groups of atoms, and now German researchers have pushed the boundaries of human visual perception to the level of individual atoms. The key component of the new microscope is the so-called electrostatic lens, through which and on the surface of which charged particles such as electrons and ions can move. Electrostatic lenses work similarly to conventional lenses used in conventional cameras and phone cameras. But if ordinary lenses refract and focus light due to the curvature of their surface, then electrostatic lenses do the same with the help of "clouds" of ions moving along their surface. Moreover, the optical parameters of electrostatic lenses are very easy to change by changing the electric potential applied to them and, consequently, the strength of the electric field. In the new microscope, scientists used a "package" of three different types of electrostatic lenses and a device that ensured that only ions of one particular type were transferred to the surface of these lenses. In addition, the design of the microscope has a special trap in which the atoms that are the objects of photography are held. In their experiments, scientists used rubidium atoms cooled to ultra-low temperatures and held in the cells of an optical lattice. The shooting itself was carried out by applying pulses of laser light, which led to the photoionization of atoms, which turned into rubidium ions. Due to some effects, these ions remained virtually immobile in their places for 30 nanoseconds, getting entangled at the quantum level with more and more nearby ions. And after that they were released into the working space of the microscope, where the survey was made. Testing the capabilities of the new microscope showed that with its help it is possible to see individual elements ranging in size from 6.79 to 0.52 micrometers with 532-nanometer intervals between them, which makes it quite possible to obtain images of individual atoms. And the depth of the created image is 70 micrometers, which is enough to create real three-dimensional images.

Other interesting news:

▪ Salt damages the kidneys

▪ Acoustic tweezers

▪ Free Wi-Fi in UK hospitals

▪ Optically Isolated Amplifiers FOD2742

▪ The Leader Brain Feature Helps Persuade

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Lighting. Article selection

▪ article Hey, Moska! know she is strong... Popular expression

▪ article Do people have the same blood? Detailed answer

▪ article Operator, user of PC and video display terminal VDT. Standard instruction on labor protection

▪ article About an antenna with an active reflector. Encyclopedia of radio electronics and electrical engineering

▪ article The formation of flakes in the reaction of potassium permanganate with sodium sulfite. Chemical experience

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024