RXD-315-KH ETC2
Document overview
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Technical content
DESCRIPTION
The KH Series is ideally suited for volume use in OEM applications such as remote control / command and keyless entry. It combines an RF receiver with an on-board decoder. When paired with a matching KH Series transmitter / encoder module, a highly reliable wireless link is formed, capable of transferring the status of 8 parallel inputs over distances in excess of 300 feet. Ten tri-state address lines provide 59,049 10)different addresses for security and uniqueness. Housed in a compact SMD package, the KH module utilizes a highly optimized SAW architecture to achieve an unmatched blend of performance, size, efficiency, and cost. No external RF components, are required (except an antenna), making design integration straightforward. KH SERIES RECEIVER / DECODER DATA GUIDE WIRELESS MADE SIMPLE® Revised 10/12/06 Figure 1: Package Dimensions 0.630" 1.430" LOT 1000 RF RECEIVER/DECODER 0.180" RXD-418-KH Remote Control / Command Keyless Entry Garage / Gate Openers Lighting Control Call Systems Home / Industrial Automation Fire / Security Alarms Remote Status Monitoring Wire Elimination APPLICATIONS INCLUDE Low cost On-board decoder 8 parallel binary outputs 310addresses for security and uniqueness No external RF components required Ultra-low power consumption Compact SMD package Stable SAW-based architecture Received data output Transmission validation No production tuning
FEATURES
PART # DESCRIPTION TXE-315-KH Transmitter / Encoder 315MHz TXE-418-KH Transmitter / Encoder 418MHz TXE-433-KH Transmitter / Encoder 433MHz RXD-315-KH Receiver / Decoder 315MHz RXD-418-KH Receiver / Decoder 418MHz RXD-433-KH Receiver / Decoder 433MHz EVAL-*-KH Basic Evaluation Kit * = Frequency Receivers are supplied in tubes of 20 pcs.
ORDERING INFORMATION
Figure 7: KH Series Receiver Pinout (Top View) Pin #Name Description 1NC No Connection. For physical support only. 2, 3, 7, 8, 9, 12, 13, D0-D7 Data Output Lines. Upon a valid transmission, these lines will be set to replicate the state of the transmitter’s address lines. 4GND Analog Ground
5 VCCSupply Voltage
6 PDN
Power Down. Pulling this line low will place the receiver into a low-current state. The module will not be able to receive a signal in this state. 10DATA Data output of the receiver prior to the encoder. 11VT Valid Transmission. This line will go high when a valid transmission is received. 15-24A0-A9 Address Lines. The state of these lines must match the state of the transmitter’s address lines in order for a transmission to be accepted. 25NC No Connection. For physical support only. 26NC No Connection. For physical support only. 27GND Analog Ground 28RF IN50-ohm RF Input PIN DESCRIPTIONS MODULE DESCRIPTION The KH Series module combines the popular Linx LC Series receiver with a decoder IC in a convenient SMD package. The module is ideal for general- purpose remote control and command applications. When paired with a matching Linx KH Series transmitter/encoder, a highly reliable RF link is formed, capable of transferring control and command data over line-of-sight distances in excess of 300 feet. The on-board receiver/decoder combination provides eight switched outputs that correspond to the state of the data lines on the transmitter’s encoder. Ten tri-state address lines are also provided to allow up to 59,049 (3 10) unique identification codes. THEORY OF OPERATION The KH Series receiver module is designed to receive transmissions from a matching KH Series transmitter module or other compatible Linx transmitter product. When transmitted data is received, the data is presented to the on- board decoder. If the incoming address data matches the local address settings, the decoder’s outputs are set to replicate the states of the transmitter’s data lines. The RF section of the KH module utilizes an advanced single-conversion superhet design that incorporates a Surface Acoustic Wave (SAW) device, high IF frequency, and multi-layer ceramic filters. The SAW device provides a highly accurate Local Oscillator (LO) frequency source with excellent immunity to frequency shift due to age or temperature. The use of SAW devices in both the KH transmitter and receiver modules allows the receiver’s pass band to be quite narrow, thus increasing sensitivity and reducing susceptibility to near-band interference. Band Select Filter pre- amplifier AM Detector SAW Local Oscillator Gilbert Cell Mixer/Amp Limiting AmpData Slicer DATA 50Ω RF IN (Ant.) 10.7MHz Bandpass Filter 10.7MHz Ceramic Filter Oscillator Buffer Sync. DetectorComparator Comparator Data Collector Divider 8-bit Shift Register Latch Circuit AND Circuit Buffer Control Logic Transmission Gate Circuit A0 A1 A2 A3 A4 A5 A6 A7 A8A9 RF Stage Decoder Stage Figure 8: KH Series Receiver Block Diagram
The KH Series receiver utilizes the HT658 decoder from Holtek. The decoder receives data transmitted by the encoder and interprets the first 10 bits of the code period as address and the last 8 bits as data. A signal on the DATA line activates the oscillator, which in turn decodes the incoming address and data. The decoder will check the received address twice continuously. If the received address code matches the decoder’s local address, the 8 bits of data are replicated on the output lines, and the VT line is set high to indicate the reception of a valid transmission. That will last until the address code is incorrect or no signal has been received. The VT line is high only when the transmission is valid, otherwise it is low. The data outputs are momentary, and follow the encoder during a valid transmission, then reset. The oscillator is disabled in the standby state and activated as long as a logic “high” signal is applied to the DATA line, so the DATA line should be kept “low” if there is no signal input. SETTING THE RECEIVER ADDRESS The module provides ten tri-state address lines. This allows for the formation of up to 59,049 (310) unique receiver-transmitter relationships. Tri-state means that the address lines can be set to one of three distinct states: high, low, or floating. These lines may be hardwired or configured via a microprocessor, DIP switch, or jumpers. The receiver’s address line states must match the transmitter’s exactly for a transmission to be recognized. If the transmitted address does not match the receiver’s local address, then the receiver will take no action. Power On Standby Mode Code In? No No No No No Yes Yes Yes Yes Yes Address Bits Matched? Disable VT & Ignore the Rest of This Word Store Data Match Previous Stored Data?
2 Times
Completed? Data to Output & Activate VT Address or Data Error? CheckCheck < 1 Word
3 Words Transmitted Continuously 3 Words
2 Words
214 Clocks214 Clocks
Figure 9: Decoder Flowchart Figure 10: Encoder / Decoder Timing Diagram THE DATA OUTPUTS When data is received and the incoming address data matches with the local address settings, the module’s eight data output lines are set to replicate the state of the transmitter’s data lines. In addition, the valid transmission line (VT, Pin 11) will go high to indicate reception and decoding of the data. The data lines have a low sink and source capability, so external buffering is generally required if loads are to be driven directly. In addition to the decoded data outputs, raw data is also available via a CMOS- compatible data output (DATA, Pin 10). The output of this line is the actual received data stream from the receiver and is always active regardless of address line status. It is made available for troubleshooting or monitoring internal data flow. It can also be used in mixed-mode systems where data may come from another source in addition to a KH Series transmitter module. This data can then be channeled to an external processor for decoding. RECEIVING DATA Although the internal decoder handles all of the decoding and output for transmissions from a KH Series transmitter or an OEM transmitter, the KH Series receiver will output the raw received data on the DATA line. This allows the designer to create a mixed system of KH Series or OEM transmitters for encoded data as well as LC or LR Series transmitters for custom data. When using the KH for custom data transmissions, it is up to the designer to implement a noise-tolerant protocol to ensure the integrity of the data. The Protocol Guidelines section will provide some suggestions, as well as Application Note AN-00160. The KH Series receiver module contains the LC Series receiver, which has a CMOS-compatible output capable of directly driving a microprocessor, an RS- 232 level converter, or a Linx QS Series USB module. The LC Series receiver manual can be consulted for more details on the operation of the receiver itself. POWER SUPPLY REQUIREMENTS The module does not have an internal voltage regulator; therefore it requires a clean, well-regulated power source. While it is preferable to power the unit from a battery, it can also be operated from a power supply as long as noise is less than 20mV. Power supply noise can affect the receiver sensitivity; therefore, providing a clean power supply for the module should be a high priority during design. A 10Ωresistor in series with the supply followed by a 10µF tantalum capacitor from V CCto ground will help in cases where the quality of supply power is poor. These values may need to be adjusted depending on the noise present on the supply line. Note that operation from 4.7 to 5.2 volts requires the use of an external 200Ωresistor placed in-line with the supply to prevent V CCfrom exceeding 4.2 volts, so the dropping resistor can take the place of the 10Ωresistor in the supply filter. 10Ω 10μF Vcc IN Vcc TO MODULE Figure 11: Supply Filter
The figure below shows an example of a basic remote control receiver utilizing the KH Series receiver module. When a key is pressed on the transmitter, a corresponding line on the receiver goes high. A schematic for the transmitter / encoder circuit may be found in the KH Series Transmitter Data Guide. These circuits are implemented in the KH Series Basic Evaluation Kit. They can be easily modified for a custom application and clearly demonstrate the ease of using the Linx KH Series modules for remote control applications. The ten-position DIP switch is used to set the address to either ground or floating. Since the floating state is a valid state, no pull-up resistors are needed. The data line outputs can only source about 1mA of current, so transistor buffers are used to drive the buzzer and LED. 1mA is sufficient to activate most microcontrollers, but the manufacturer’s data guides should be consulted to make sure. The KH Series receiver / decoder module is also suitable for use with Linx OEM handheld transmitters. These transmitters are FCC certified, making product introduction extremely quick. Information on these transmitters can be found on the Linx website at www.linxtechnologies.com. 2N2222R2 2.2k 10k BZ1 BUZZER VCC 2N2222R3 2.2k 10k LED1 RED LED
220 OHM
Figure 12: Basic Remote Control Receiver Figure 13: Linx OEM Transmitters Figure 14: Linx OEM Keyfobs PROTOCOL GUIDELINES While many RF solutions impose data formatting and balancing requirements, Linx RF modules do not encode or packetize the signal content in any manner. The received signal will be affected by such factors as noise, edge jitter, and interference, but it is not purposefully manipulated or altered by the modules. This gives the designer tremendous flexibility for protocol design and interface. Despite this transparency and ease of use, it must be recognized that there are distinct differences between a wired and a wireless environment. Issues such as interference and contention must be understood and allowed for in the design process. To learn more about protocol considerations, we suggest you read Linx Application Note AN-00160. Errors from interference or changing signal conditions can cause corruption of the data packet, so it is generally wise to structure the data being sent into small packets. This allows errors to be managed without affecting large amounts of data. A simple checksum or CRC could be used for basic error detection. Once an error is detected, the protocol designer may wish to simply discard the corrupt data or implement a more sophisticated scheme to correct it. INTERFERENCE CONSIDERATIONS The RF spectrum is crowded and the potential for conflict with other unwanted sources of RF is very real. While all RF products are at risk from interference, its effects can be minimized by better understanding its characteristics. Interference may come from internal or external sources. The first step is to eliminate interference from noise sources on the board. This means paying careful attention to layout, grounding, filtering, and bypassing in order to eliminate all radiated and conducted interference paths. For many products, this is straightforward; however, products containing components such as switching power supplies, motors, crystals, and other potential sources of noise must be approached with care. Comparing your own design with a Linx evaluation board can help to determine if and at what level design-specific interference is present. External interference can manifest itself in a variety of ways. Low-level interference will produce noise and hashing on the output and reduce the link’s overall range. High-level interference is caused by nearby products sharing the same frequency or from near-band high-power devices. It can even come from your own products if more than one transmitter is active in the same area. It is important to remember that only one transmitter at a time can occupy a frequency, regardless of the coding of the transmitted signal. This type of interference is less common than those mentioned previously, but in severe cases it can prevent all useful function of the affected device. Although technically it is not interference, multipath is also a factor to be understood. Multipath is a term used to refer to the signal cancellation effects that occur when RF waves arrive at the receiver in different phase relationships. This effect is a particularly significant factor in interior environments where objects provide many different signal reflection paths. Multipath cancellation results in lowered signal levels at the receiver and, thus, shorter useful distances for the link.
A whip-style antenna provides outstanding overall performance and stability. A low-cost whip is can be easily fabricated from a wire or rod, but most designers opt for the consistent performance and cosmetic appeal of a professionally-made model. To meet this need, Linx offers a wide variety of straight and reduced-height whip-style antennas in permanent and connectorized mounting styles. The wavelength of the operational frequency determines an antenna’s overall length. Since a full wavelength is often quite long, a partial 1/2- or 1/4-wave antenna is normally employed. Its size and natural radiation resistance make it well matched to Linx modules. The proper length for a straight 1/4-wave can be easily determined using the adjacent formula. It is also possible to reduce the overall height of the antenna by using a helical winding. This reduces the antenna’s bandwidth, but is a great way to minimize the antenna’s physical size for compact applications. This also means that the physical appearance is not always an indicator of the antenna’s frequency. Linx offers a wide variety of specialized antenna styles. Many of these styles utilize helical elements to reduce the overall antenna size while maintaining reasonable performance. A helical antenna’s bandwidth is often quite narrow and the antenna can detune in proximity to other objects, so care must be exercised in layout and placement. Whip Style Loop Style L =234 FMHz Where:L = length in feet ofquarter-wave length F = operating frequencyin megahertz Specialty Styles A loop- or trace-style antenna is normally printed directly on a product’s PCB. This makes it the most cost-effective of antenna styles. The element can be made self-resonant or externally resonated with discrete components, but its actual layout is usually product specific. Despite the cost advantages, loop-style antennas are generally inefficient and useful only for short-range applications. They are also very sensitive to changes in layout and PCB dielectric, which can cause consistency issues during production. In addition, printed styles are difficult to engineer, requiring the use of expensive equipment, including a network analyzer. An improperly designed loop will have a high SWR at the desired frequency, which can cause instability in the RF stage. Linx offers low-cost planar and chip antennas that mount directly to a product’s PCB. These tiny antennas do not require testing and provide excellent performance in light of their small size. They offer a preferable alternative to the often-problematic “printed” antenna. COMMON ANTENNA STYLES There are literally hundreds of antenna styles and variations that can be employed with Linx RF modules. Following is a brief discussion of the styles most commonly utilized. Additional antenna information can be found in Linx Application Notes AN-00100, AN-00140, and AN-00500. Linx antennas and connectors offer outstanding performance at a low price. ONLINE RESOURCES Latest News Data Guides Application Notes Knowledgebase Software Updates If you have questions regarding any Linx product and have Internet access, make www.linxtechnologies.com your first stop. Our website is organized in an intuitive format to immediately give you the answers you need. Day or night, the Linx website gives you instant access to the latest information regarding the products and services of Linx. It’s all here: manual and software updates, application notes, a comprehensive knowledgebase, FCC information, and much more. Be sure to visit often! www.antennafactor.com The Antenna Factor division of Linx offers a diverse array of antenna styles, many of which are optimized for use with our RF modules. From innovative embeddable antennas to low-cost whips, domes to Yagis, and even GPS, Antenna Factor likely has an antenna for you, or can design one to meet your requirements. www.connectorcity.com Through its Connector City division, Linx offers a wide selection of high-quality RF connectors, including FCC- compliant types such as RP-SMAs that are an ideal match for our modules and antennas. Connector City focuses on high-volume OEM requirements, which allows standard and custom RF connectors to be offered at a remarkably low cost. www.linxtechnologies.com
When working with RF, a clear distinction must be made between what is technically possible and what is legally acceptable in the country where operation is intended. Many manufacturers have avoided incorporating RF into their products as a result of uncertainty and even fear of the approval and certification process. Here at Linx, our desire is not only to expedite the design process, but also to assist you in achieving a clear idea of what is involved in obtaining the necessary approvals to legally market your completed product. In the United States, the approval process is actually quite straightforward. The regulations governing RF devices and the enforcement of them are the responsibility of the Federal Communications Commission (FCC). The regulations are contained in Title 47 of the Code of Federal Regulations (CFR). Title 47 is made up of numerous volumes; however, all regulations applicable to this module are contained in Volume 0-19. It is strongly recommended that a copy be obtained from the Government Printing Office in Washington or from your local government bookstore. Excerpts of applicable sections are included with Linx evaluation kits or may be obtained from the Linx Technologies website, www.linxtechnologies.com. In brief, these rules require that any device that intentionally radiates RF energy be approved, that is, tested for compliance and issued a unique identification number. This is a relatively painless process. Linx offers full EMC pre- compliance testing in our HP / Emco-equipped test center. Final compliance testing is then performed by one of the many independent testing laboratories across the country. Many labs can also provide other certifications that the product may require at the same time, such as UL, CLASS A / B, etc. Once your completed product has passed, you will be issued an ID number that is to be clearly placed on each product manufactured. Questions regarding interpretations of the Part 2 and Part 15 rules or measurement procedures used to test intentional radiators, such as Linx RF modules, for compliance with the technical standards of Part 15, should be addressed to: Federal Communications Commission Equipment Authorization Division Customer Service Branch, MS 1300F2
7435 Oakland Mills Road
Columbia, MD 21046 Phone: (301) 725-1585 Fax: (301) 344-2050 E-Mail: labinfo@fcc.gov International approvals are slightly more complex, although Linx modules are designed to allow all international standards to be met. If you are considering the export of your product abroad, you should contact Linx Technologies to determine the specific suitability of the module to your application. All Linx modules are designed with the approval process in mind and thus much of the frustration that is typically experienced with a discrete design is eliminated. Approval is still dependent on many factors, such as the choice of antennas, correct use of the frequency selected, and physical packaging. While some extra cost and design effort are required to address these issues, the additional usefulness and profitability added to a product by RF makes the effort more than worthwhile. NOTE:Linx RF modules are designed as component devices that require external components to function. The modules are intended to allow for full Part 15 compliance; however, they are not approved by the FCC or any other agency worldwide. The purchaser understands that approvals may be required prior to the sale or operation of the device, and agrees to utilize the component in keeping with all laws governing its use in the country of operation. ACHIEVING A SUCCESSFUL RF IMPLEMENTATION Adding an RF stage brings an exciting new dimension to any product. It also means that additional effort and commitment will be needed to bring the product successfully to market. By utilizing premade RF modules, such as the LR Series, the design and approval process is greatly simplified. It is still important, however, to have an objective view of the steps necessary to ensure a successful RF integration. Since the capabilities of each customer vary widely, it is difficult to recommend one particular design path, but most projects follow steps similar to those shown at the right. In reviewing this sample design path, you may notice that Linx offers a variety of services (such as antenna design and FCC prequalification) that are unusual for a high-volume component manufacturer. These services, along with an exceptional level of technical support, are offered because we recognize that RF is a complex science requiring the highest caliber of products and support. “Wireless Made Simple” is more than just a motto, it’s our commitment. By choosing Linx as your RF partner and taking advantage of the resources we offer, you will not only survive implementing RF, you may even find the process enjoyable. HELPFUL APPLICATION NOTES FROM LINX It is not the intention of this manual to address in depth many of the issues that should be considered to ensure that the modules function correctly and deliver the maximum possible performance. As you proceed with your design, you may wish to obtain one or more of the following application notes, which address in depth key areas of RF design and application of Linx products. These applications notes are available online at www.linxtechnologies.com or by contacting the Linx literature department. DECIDE TO UTILIZE RF RESEARCH RF OPTIONS CHOOSE LINX MODULE ORDER EVALUATION KIT(S) TEST MODULE(S) WITH BASIC HOOKUP INTERFACE TO CHOSEN CIRCUIT AND DEBUG CONSULT LINX REGARDING ANTENNA OPTIONS AND DESIGN LAY OUT BOARD SEND PRODUCTION-READY PROTOTYPE TO LINX FOR EMC PRESCREENING OPTIMIZE USING RF SUMMARY GENERATED BY LINX SEND TO PART 15 TEST FACILITY RECEIVE FCC ID # COMMENCE SELLING PRODUCT Typical Steps For Implementing RF AN-00100 RF 101: Information for the RF Challenged AN-00125 Considerations For Operation Within The 260-470MHz Band AN-00130 Modulation Techniques For Low-Cost RF Data Links AN-00140 The FCC Road: Part 15 From Concept To Approval AN-00150 Use and Design of T-Attenuation Pads AN-00160 Considerations For Sending Data Over a Wireless Link AN-00300 Addressing Linx OEM Products AN-00500 Antennas: Design, Application, Performance NOTE APPLICATION NOTE TITLE
LINX TECHNOLOGIES, INC.
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MERLIN, OR 97532 PHONE: (541) 471-6256 FAX: (541) 471-6251 www.linxtechnologies.com U.S. CORPORATE HEADQUARTERS WIRELESS MADE SIMPLE® Linx Technologies is continually striving to improve the quality and function of its products. For this reason, we reserve the right to make changes without notice. The information contained in this Data Guide is believed to be accurate as of the time of publication. Specifications are based on representative lot samples. Values may vary from lot to lot and are not guaranteed. Linx Technologies makes no guarantee, warranty, or representation regarding the suitability or legality of any product for use in a specific application. None of these devices is intended for use in applications of a critical nature where the safety of life or property is at risk. The user assumes full liability for the use of product in such applications. Under no conditions will Linx Technologies be responsible for losses arising from the use or failure of the device in any application, other than the repair, replacement, or refund limited to the original product purchase price. Disclaimer © 2006 by Linx Technologies, Inc. The stylized Linx logo, Linx, “Wireless Made Simple”, CipherLinx and the stylized CL logo are the trademarks of Linx Technologies, Inc. Printed in U.S.A.