FreeScale: Reference Design for Electric Field Lighting Controllers with Wireless Connectivity

In the future, mechanical lighting control switches will be phased out. Capacitive touch proximity sensors equipped with simple linear or rotating sliding sensor plates offer significant advantages in home lighting applications. They are easier to use, contain no easily worn moving parts, are more energy-efficient, and are easier to integrate into home network systems. Freescale demonstrates these advantages in a reference design for an electric field (E-Field) lighting controller with wireless connectivity. This controller features a proximity sensor rotating slider for smooth dimming control and integrates ZigBee® SMAC technology for wireless control of four independent smart sockets. This reference design demonstrates a design for comprehensive digital dimming control of bulbs via a 3-axis assembly. This 3-axis assembly is typically used as a low-cost solution for driving line voltage. The system is based on the Freescale MC1321x and includes two devices: a smart switch and a smart socket. The smart switch provides dimming functionality via one phase of the power supply. The user control interface is implemented using Freescale's electric field imaging device (MC33794). This functional component provides a contactless touch panel with various electrode shapes. The smart switch can also remotely control four smart sockets via RF communication capabilities of the SMAC layer. The smart socket simply acts as a receiver of commands issued by the smart switch. This device is used for dimming standard incandescent table lamps. Pulse width modulation (PWM) technology can be used to adjust the reference sine wave of the power supply. The system can be fully customized to customer requirements with only software modifications. The MC1321x series includes an embedded flash microcontroller offering diverse combinations of Freescale peripherals and featuring an SoC core and advanced 802.15.4 functionality. An RF modem can be used to implement various wireless network topologies. It is an excellent solution for power- and size-sensitive applications such as wireless communications and handheld devices. Detailed application descriptions, including hardware and software design, are provided in the Designer Reference Manual DRM096. We also provide hardware schematics, PCB Gerber files, and a software manifest. (Please note that the Bill of Materials (BOM) for this reference design is included in Designer Reference Manual DRM096.) The proximity sensor-based remote control is an example of an advanced universal remote control that integrates Freescale's following components and technologies: wireless ZigBee® (SMAC) 2.4 GHz connectivity, an accelerometer, and capacitive proximity sensing technology, all within a single application. The board is housed in a lightweight, small plastic housing and powered by two AAA batteries. The core component of the board is an 8-bit MC13213 MCU, which includes an S08 core and an 802.15.4 RF modem, all integrated into a single package. This design is used for assembling low-power 3-axis accelerometers, either analog MMA7340L or digital MMA7456L versions. The contactless user interface is implemented via a 10-element electrode keypad controlled by touch-sensitive software deployed in an MC9S08QG8. An example of implementing electric field lighting dimming is provided. Detailed application descriptions, including hardware and software design, are provided in Application Note AN3783. We also provide hardware schematics, PCB Gerber files, and a software inventory. Features: Smart Switch; Dimming bulbs via a single phase using a 3-axis component (device in series with bulb); Provides a comfortable contactless user interface via Freescale MC33794 electric field sensor; Remotely controls up to 4 smart sockets via an 802.15.4 RF modem using the SMAC software layer; Multiple touch panel designs; Maximum dimming level up to 90% of the bulb's maximum luminous intensity; Energy-saving features; Easy to implement in the home without replacing or modifying existing installations; Dimming incandescent bulbs from 40-200VA; Device can use 230VAC/50 Hz or 115VAC/60 Hz power supply +12V DC/200mA internal switching power supply; Can be controlled using a calibrated Flextronics remote control; Smart Socket; Dimming bulbs via a 3-axis component (device in parallel with bulb); Smart Switch remotely controlled using an 802.15.4 RF modem; Hardware ID selector identifies the device in the RF wireless network; Energy-saving features; Easy to implement in the home without replacing or modifying existing installations; Dimming bulbs within a 40-200VA power supply range. The device can operate on 230VAC/50 Hz or 115VAC/60 Hz power supplies with an internal +12V DC/200mA switching power supply. It can be controlled using a calibrated Flextronics remote control. The device MC13211/212/213/214 (ZigBee compliant platform—2.4 GHz low-power transceiver and microcontroller) is an on-chip transceiver/2.4 GHz modem compliant with IEEE 802.15.4. It features multiple power-saving modes, an on-chip regulator operating from 2V to 3.4V, and requires minimal external components. It supports 16 MHz single-crystal clock source operation or dual-crystal operation. It supports SMAC, IEEE® 802.15.4, and ZigBee software. It has a 9mm x 9mm x 1mm 71-pin LGA and a Freescale MC33794 proximity sensor. It supports up to 9 electrodes and two reference electrodes. A shielded driver is provided for driving the remote control electrodes via a coaxial cable. It operates via +5.0V. A DC regulator powers the external circuitry. An ISO-9141 physical layer interface is used. The proximity sensor-based remote control utilizes a 10-element touchpad for software-based proximity sensing. The circuit board is designed for small plastic housings. Tilt motion data from a 3-axis MMA7340L/MMA7456L accelerometer is used for customizable adjustment modes. Six built-in LEDs indicate internal status. The proximity sensor-based remote control circuit board is powered by two AAA batteries. RF communication is achieved via an 802.15.4 modem using SMAC protocol layer software.