The rapid deployment of smart Internet products pushes the demand for wireless switches and promotes the interconnection of the equipment. Since it is a wireless switch, no additional connection wire is required, and it is convenient to arrange. However, since the wireless switches used in recent years are battery power-saving switches, design costs and complexity are added in invisible, and the user needs battery replacement. Solutions may have to rely on energy collection in the form of inductance.
There are many sources of environmental energy, including photons, radio frequency energy, vibration, temperature difference and pressure. However, this article will introduce an inductive energy collection reference design; the design uses a novel approach based on Bluetooth and EDDYSTOONE open beacon protocol, using the parts of the two companies in Semiconductor and ZF Electronics.
By supporting the design and related development kits together, it will be able to provide all the electric energy required to support the Bluetooth center or smart product transmission signal for ultra-low power Bluetooth 5.0 modules.
Ultra low power design
On Semiconductor's BLE-SWITCH001-GEVB development kit will directly replace the Bluetooth 5.0 module and the energy collection mechanical switch to provide developers with an instant wireless switch solution and lay the foundation for custom wireless switch design. In this design, the AFIG-0007 inductive energy collector of the ZF Electronics will provide sufficient power to the ON Semiconductor's RSL10 Bluetooth 5 System Level Package (SIP) to make it sufficient to transmit low-power Bluetooth (BLE) beacons. After receiving the beacon, the BLE-supporting receiver can perform related operations to control lights, relays or other devices.
The key to this non-battery design is that the RSL10 is perfectly matched to the power requirements of the beacon transmission with the AFIG-0007 to meet the ability of these requirements.
The RSL10 module is designed to meet the emerging needs of low-power wireless connections, which integrates multiple functional blocks that provide a complete Bluetooth 5 solution (Figure 1). For processing, the module is equipped with two kernels, one is the ARM® Cortex®-M3 kernel responsible for universal processing, and the other is the ON Semiconductor's own LPDSP32 32-bit Digital Signal Processor (DSP) kernel for a particular application.
The module supports the above processor using multiple peripherals and memory (including 384 KB flash, 76 KB program memory, and 88 KB data memories). For Bluetooth communication, the module is equipped with a 2.4 giga (GHz) RF front end supporting Bluetooth Physical Layer (PHY), and a baseband controller that supports advanced Bluetooth 5.0 protocol.
RSL10 can operate within 1.1 - 3.3 volts wide power supply voltage range, and power consumption is extremely low. Ulpmark ultra low power (ULP) benchmarks using an embedded microprocessor benchmark (EEMB) association, RSL10 can reach the industry's leading 1090 points at the 3 volt supply, and can reach 1360 points at 2.1 volts.
However, in many wireless applications, the power required to repeated long-term wireless transactions may test the limit of this highest energy efficiency design. The referential design of the ON Semiconductor solves how to use the Bluetooth beacon protocol to achieve shorter wireless transaction processing time.
The beacon is a short message compliant with the Bluetooth ad protocol for any available listener broadcast identifiers or other short data segments. By cooperating with dedicated mobile applications, beacons are widely used in retail, entertainment, transportation and other public applications, providing information related to user location. On Semiconductor's wireless switch design uses a special beacon, called the Eddystone beacon.
The EddyStone beacon follows an open standard that specifies the envelope and data payload associated with the packet (length only to several bytes). For EddyStone beacons, the payload format can specify a unique ID (UUID), a URL, or different types of telemetry (TLM) data, such as temperature (Figure 2).
After finding the Eddystone beacon, the receiving application can perform an operation related to the UUID and send the user to the URL, or make appropriate responses to telemetry data.
Energy collection source
The transmission time of the Eddystone beacon may be short to 10 milliseconds (MS), and the energy required to complete this transmission is as low as 100 millocused (MJ), which is completely in the AFIG-0007 energy using ultra-low power RSL10. The collector's power generation capacity range.
Within AFIG-0007, the coil surrounds around the metal magnetic core in contact with the magnetic block (Fig. 3, the left). When the user presses the spring actuator, the magnetic block will move (Figure 3, right). This operation reverses the polarity of the magnetic field passing through the coil to generate a power pulse according to the magnetic induction principle. Loosing the actuator will cause the magnetic block to the original position to generate another energy pulse having opposite polarity.
The ZF energy collector size is 20 x 7 x 15 mm (mm), and the life expectancy is 1,000,000 switching cycles, which meets the key mechanical and physical requirements for wireless switch design. The AFIG-0007 can easily meet the energy requirements of this design. ZF can generate an energy of about 300 mJ in each press and release actuation cycle, which provides sufficient power to RSL10 to transmit two to three EDDYSTOONE beacons. In addition to these two parts, the implementation of wireless switch design simply adds other small components to complete energy collection power circuitry.
Energy collection power supply circuit design
Typically, the energy collecting the power supply circuit needs to use the voltage converter and the coil to enable the generated voltage level to reach the precise level required for the microcontroller. In this design, the RSL10's 1.1 to 3.3 volt wide power supply range simplifies the design of the power supply circuit. The output of the AFIG-007 is rectified by the NSR1030 Schottky full bridge rectifier, and is made by a simple circuit, which includes an SZMM3Z6V2ST1G Zener diode, a filter / energy storage capacitor (C1), and an NCP170 low pressure difference (LDO) The regulator, all of which are from ON Semiconductor (Figure 4).
On Semiconductor's BLE-SWITCH001-GEVB suite integrates AFIG-007 and the above-described power supply circuit and RSL10 on a circuit board having a size of 23 x 23 mm (Fig. 5).
The 7 mm wide central area contains a core component, while the detachable wing provides a number of development interfaces, including a 10-pin JTAG / SWD interface for standard adapters (such as TAG-Connect TC2050-IDC). In addition to the 10-pin interface, the side flap also provides a needle holder for jumpers and external 3.3 volts (VOUT) to use connected JTAG programmers (such as Segger MicroController Systems 8.16.28 J-Link Ultra +) Perform programming and debugging.
Switch circuit design
The BLE-SWITCH001-GEVB board has been pre-assembled, and the EDDYSTONE beacon is sent every 20 ms until the system depletes the power generated by the single switch actuation. In this application example, the design first sends an eddystone-URL frame containing the URL "https://onsemi.com/idk". After sending this initial frame, the design transmits the EDDYSTONE TLM frame containing telemetry data, including the power supply voltage, normal running time, and the total number of packets transmitted so far.
The ON Semiconductor's RSL10 EDDYSTONE sample software demonstrates the basic design mode of building and sending frames (Listing 1). As shown in Listing 1, the developer call function EDDYSERVICE_ENV_INITIALIZE () will load the payload of the Eddystone-URL frame to the EDDYSTONE environment structure EDDY_ENV_TAG. In order to send a beacon, the developer calls the eddy_gattc_writereqind () function, which is used to build a package, encrypt the data with the AES encryption accelerator of the RSL10, and then send the message (Ke_MSG_send ()) to the transmission queue. The lower service layer is used to retrieve the queuing message, build a packet, and transmit it.
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The transmitted beacon can be displayed in the range of any support for BLE, or is displayed in the vicinity of mobile devices (such as ON Semiconductor's RSL10 mobile app). To use the wireless switch control device, the developer can use the ON Semiconductor based on the RSL10's BDK-GEVK BLE Internet development kit and execute the relevant operation. For example, developers can use the BDK-GEVK substrate and the D-LED-B-GEVK dual LED ballar plate of On Semiconductor to use the wireless switch to implement control of the lamp. When designing a motor drive type, developers can combine the substrate with the On Semiconductor's BLDC-GEVK brushless DC motor drive board or D-STPR-GEVK step motor driver plate.
Finally, when deploying a wireless switch, the developer only needs to remove the two flaps, leaving only a 7 x 23 mm component containing all the functional devices (Figure 6).
Since the ZF actuator is located behind the rear end of the assembly, it can be placed under the rocker switch in an empty shell like CW Industries Gil-2000-2010.
Summarize
The wireless switch provides a maintenance-free solution for rapid growth of smart product control. However, since the traditional wireless design requires a battery to operate, it has increased design cost and complexity, and users have to handle battery management and replacement. On Semiconductor's reference design solves these problems to a large extent, this design utilizes energy collection technology, providing all of the electric energy required for ultra-low power Bluetooth 5.0 modules, can wirelessly support Bluetooth central or intelligence Product sends signal.
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