In order to meet the development needs of home intelligence and networkization, a design scheme of light controllers based on ZigBee and capacitive touch technology is proposed, and the system design is completed. The focus describes the system's power drive circuit, touch induction circuit, and implementation of CC2530. The actual application shows that the system has a safe and reliable, accurate manipulation, convenient networking, and has achieved design requirements.
Under the trend of the Internet of Things. Home equipment has developed towards intelligent, digitized and networking. The light control switch has a broad market prospect as the most common control equipment of the family, design reliable security, new light controller for remote control meets development requirements and market demand. ZigBee as a low power, low rate wireless communication protocol. Its characteristics make it possible to make it in the field of smart home, public safety, industrial monitoring, etc.; therefore, ZigBee technology is applied to the design of the light controller, which can meet the controller for low power and networked. Demand. The capacitive touch technology has the advantages of accurate manipulation, safe and reliable, long service life. This technology is applied to the field of lighting control. A new type of control switch with touch sensing function can be designed. Lighting Control Switch Based on ZigBee Technology and Capacitor Touch Design. It has the advantages of high sensitivity, waterproof safety, long service life, and facilitating networking. It can be widely used in the field of smart homes, with a certain market prospect.
1 design plan
ZigBee is a clustered extension based on IEEE802.11.4 protocol. Mainly for low-cost, low-power RF applications. Low cost is widely used in the application of intelligent home directions. Low-time consumption has a longer working cycle: its supported wireless network network has stronger reliability and wider coverage: wireless communication through this protocol in the light control switch, used to support remote control and group Network control.
The panel of the light control switch is made of an organic glass. The induction electrode is located below the glass and is tightly passed closely with the glass panel, and the finger is touched above the electrode, and the change in capacitance can cause the capacitance. This change transitions into electrical signals to provide the processor for correlators: The capacitance touch chip we use in this case to complete the function of the touch section.
The overall configuration diagram of the control switch is shown in Figure 1. It mainly includes a capacitive sensing processing section, a ZigBee master processor portion, a drive control section, and a power management section.
2 induction part design
The induction portion mainly includes an insulating panel, a button induction disk, and a capacitor processing chip. The panel must be an insulating material. We use organic glass as a touch panel. The dielectric constant of the glass is moderate, and the dielectric constant is too small. The sensitivity is relatively poor, and the dielectric constant is too large. The chance of malfunction will increase. The key induction disk is used to use the PCB copper foil, and the induction disk is designed on the PCB circuit board. According to the actual situation, the circular induction disc of 10 mm is selected according to the actual situation, and the shape of each induction disk is the same, the same sensitivity is maintained. The distance between the distance is allowed to reduce electric field interference between mutual interference. Between the induction discs are separated as much as possible. The induction chip is selected from the ST series of blind microelectronics. Meet the design needs.
The alopecia is shown in Figure 2. The PCB sensing disk PAD is connected to the induction chip, and the capacitance of 10 pf is used to adjust the sensitivity of the touch sensing. The higher the capacitance value, the higher the sensitivity: the induction chip changes the input level changes by the output port at a low level. The interrupt signal is transmitted to the ZigBee master processor chip.
3 ZigBee main processor design
The ZigBee chip selected by this device is CC2530. The CC2530 is a real system for IEEE802.15.4, ZigBee and RF4CE applications. It can establish a powerful network node at very low total material: CC2530 integrates an industry's RF transceiver, enhances the 8051 MCU of industry standards, which can program MASH memory in the system. 8-KBRAM and many other powerful functions. The circuit diagram of the CC2530 section is shown in Figure 3. Two crystals 32 MHz and 32.768 kHz. Among them, 32.768 kHz crystal is mainly used to sleep timer. In practical applications, if it is not necessary to remove costs; the RF terminal receives the antenna after processing. The antenna can be an external antenna or a PCB antenna. This device is designed in the F-shaped PCB antenna. The flyback F antenna has a simple structure, low weight, conformal, manufacturing cost, high radiation efficiency, and easy to realize multi-band work, which is ideal for application to this device. .
4 power supply part design
The power supply part needs to process the power supply of the AC 220 V to low voltage DC is a processing circuit, a control circuit, and the like provide a suitable power source. We use the switch off the power regulator chip Viperl2a to achieve the function of the switching power supply portion, to obtain a stable output voltage 5 V, the DC power supply of the output current LA. Viperl2a is a chip product that is designed to optimally optimally use a dedicated current mode PWM controller and a high pressure power MOSFET; Viperl2a has automatic thermal shutdown in an interior. High voltage start current source, prevent output short circuits to ensure low power consumption in low loads.
Viperl2a partial circuit diagram is shown in Figure 4. Rectified voltage enters the chip, the ViPerL2a's pin voltage supports the range of 8 V to 40 V, and the output feedback enters the chip through the optocouple device PC817C, and the feedback current is used for the work of the chip control device.
After obtaining the DC 5 V voltage by the switching power supply. 5 V bumps are obtained from the Zigee processor to the Zigee processor via the LDO device to obtain a 3.3 V DC voltage.
5 Drive part design
The driving portion is mainly to achieve the interworking control of AC power by driving the relay. The circuit of the drive relay portion is shown in Figure 5, and a negative logic drive circuit is realized by two diodes by NPN and PNP, which is strongly driven. You can avoid malfunction of the relay when the main control chip is powered on power-on. The relay coil end is parallel to one 4148 diode, the diode reverse receiver used to release the current in the relay coil, the protection switch and the triode and other devices are not damaged by the coil induction voltage.
6 conclusion
This light control switch is based on ZigBee and capacitor touch technology. The actual application shows that the control switch is beautiful, safe and reliable, flexible, and is easy to network, and network control can achieve design requirements.
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Source: Wiku Electronic Market Network
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