Application Note: AS3935-AN09 – Keychain Reference Design AS3935 AN09-Keychain Reference Design www.ams.com Revision 1.0 / 24/01/14 page 1/10 AS3935-AN09 Keychain Reference Design Table of Contents 1 General Description ............................................................................................................. 3 2 Getting Started ..................................................................................................................... 3 3 Hardware Description........................................................................................................... 3 4 Sensor Settings .................................................................................................................... 4 5 Detailed Description – Case Studies ................................................................................... 5 5.1 No Lightning ......................................................................................................................... 5 5.2 Lightning at 20 km ................................................................................................................ 5 5.3 Lightning Recedes ............................................................................................................... 6 5.4 Disturbances ........................................................................................................................ 6 6 Operation Environment ........................................................................................................ 6 7 Board Schematics, Layout and BOM ................................................................................... 7 7.1 Schematic ............................................................................................................................ 7 7.2 Layout .................................................................................................................................. 8 7.3 Bill of Materials ..................................................................................................................... 9 Revision History Revision Date Owner Description 1.0 24.01.2014 JRY Initial Release www.ams.com Revision 1.0 / 24/01/14 page 2/10 AS3935-AN09 Keychain Reference Design 1 General Description Fast moving storms with lightning pose a serious threat to personal safety when shelter is not TM nearby. Now, with the invention of the Franklin Lightning Sensor IC, truly portable lightning detectors can be the size of a wristwatch and operate for months with a coin cell battery. In fact, the highly integrated AS3935 from ams can be easily integrated into existing products such as GPS, weather stations, fish finders and many other battery powered consumer electronic devices. This application note contains instructions for proper operation of the Franklin Lightning Sensor demonstrator using certain scenarios as key examples 2 TM Getting Started Turn on the lightning detector by pressing the on/off button (J). The buzzer signals once and the indicator LEDs light up one after the other. Battery strength: the number of LEDs that light up indicates the amount of battery charge. The battery is empty only when the “near” LED lights up after turning on the device. The lightning detector is automatically switched to listening mode which is indicated by the “far” LED blinking continuously. Turn off the lightning detector by pressing the on/off button again (J). 3 Hardware Description Figure 1: Hardware Description C B G D A F H E J www.ams.com Revision 1.0 / 24/01/14 page 3/10 AS3935-AN09 Keychain Reference Design Label Designator Description Info A U3 AS3935 Franklin Lightning TM Sensor B C5, C6, R9 Tuning Circuit Tuning capacitors and Q adjustment resistor C ANT1 RFID Transponder Coil D near … far Distance indicator LEDs The current distance to the storm is indicated by the currently blinking LED E U2 Microcontroller PIC16F616-I F J1 Programming Interface G U1 Battery Holder CR2032 coin cell H X1 Buzzer Audible indication of detected lightning events J S1 On/Off switch 4 Sensor Settings The Keychain reference design does not offer the possibility to change the chip settings. Therefore, the device is set for an outdoor environment. Additionally, the minimum number of strikes feature is used to minimize the possibility of false alerts. All other settings which are not given in the table below are set to default as described in the AS3935 datasheet. Figure 2: AS3935 Keychain Settings Register [hex] Value [hex] Description 0x00 0x1C Gain = Outdoor 0x01 0x24 Noise Floor default, Watchdog threshold 4 0x02 0xD2 Minimum Number of lightning = 5 0x03 0xC0 Antenna frequency divided by 128 for start-up tuning www.ams.com Revision 1.0 / 24/01/14 page 4/10 AS3935-AN09 Keychain Reference Design 5 Detailed Description – Case Studies 5.1 No Lightning The lightning detector is switched on and no lightning has been detected. The “far” LED blinks continuously indicating that there are no lightning storms within range. Figure 3: There is no lightning within reach 5.2 Lightning at 20 km The buzzer signals once and all LEDs starting from “far” to “20 km” light up. Then the “20 km” LED will blink continuously indicating that the closest lightning detected was at distance of 20 km. Figure 4: Lightning detected at 20 km www.ams.com Revision 1.0 / 24/01/14 page 5/10 AS3935-AN09 Keychain Reference Design 5.3 Lightning Recedes As the lightning storm moves away, indicator lights will move towards “far”. Figure 5: Lightning storm is moving away 5.4 Disturbances The LED indicating the closest lightning detected blinks quickly several times. This means that signals coming from electronic devices such as mobile phones are being detected. Make sure that electronic devices that can produce interfering signals are not close to the detector. Figure 6: Non-lightning signals are being detected 6 Operation Environment Be advised that the lightning detector will not work properly when close to electronic devices such as computers or cell phones. The noise from such devices can prevent the lightning detector from detecting lightning signals. If this is the case, move the lightning detector away from electronic devices until the currently active indicator LED starts blinking with the normal blinking frequency. www.ams.com Revision 1.0 / 24/01/14 page 6/10 AS3935-AN09 Keychain Reference Design 7 Board Schematics, Layout and BOM 7.1 Schematic Figure 7: AS3935 Franklin Lightning Sensor 1 TM Keychain Reference Design Schematic 2 3 4 J1 VCC 6 5 4 3 2 1 VCC VCC GND A A GND C1 R1 10k C2 10u UART_TX MCLR - D3 R6 820R 1 UART_TX 17 13 U2 PIC16F616 EP VSS 14 NC 15 VDD NEAR VCC NC 16 + 100n GND U1 Batterie 20km RA5/T1CKI/OSC1/CLKIN RA0/C1IN+/ICSPDAT R2 12 10km GND VCC D6 2 R5 820R RA4/T1G/OSC2/CLKOUTRA1/C12IN0-/ICSPCLK GND C5 C6 680pF 270pF 2 R9 10k INP INN VREG 6 EP SI IRQ B RC1/C12IN1- RC2/C12IN2- RC0/C2IN1+ 10 5km R7 9 D5 VCC 820R 8 GND 7 5 GND 9 R11 820R GND D7 GND VCC R12 R13 FAR 10k 10k 10 VCC C VCC VCC X1 VCC GND RC5 VCC 14 12 MISO 13 I2CD_MOSI 11 I2CL_SCLK 8 CS C 17 TEST 4 D4 820R RA2/T0CKI/INT/C1OUT RC3/C12IN3- S1 ON/OFF 1 4 AS3935 EN_VREG 3 16 ADD1 15 ADD0 ACG 10u 11 7 1 GND ANT1 100uH GND 5 VDD C4 U3 AS3935_QFN VCC RC4/C2OUT 2 RA3/MCLR/VPP 6 3 MCLR C3 100n VCC 40km R4 PIC16F610 VCC B D2 820R R8 1k5 C7 GND 10u GND GND Piezo_SMD GND Confidential © ams AG 2013 Project: AS3935 Keychain D 2.0 2.0.0 Application Engineer: JRY Page Size: A4 1 www.ams.com 2 3 Revision 1.0 / 24/01/14 D 26.11.2013 Sheet 3 of 3 4 page 7/10 AS3935-AN09 Keychain Reference Design 7.2 Layout Figure 8: AS3935 Franklin Lightning Sensor TM Keychain Reference Design – Top Layer Figure 9: AS3935 Franklin Lightning Sensor TM Keychain Reference Design – Bottom Layer www.ams.com Revision 1.0 / 24/01/14 page 8/10 AS3935-AN09 Keychain Reference Design 7.3 Bill of Materials Figure 10: AS3935 Franklin Lightning Sensor www.ams.com TM Keychain Reference Design BOM Revision 1.0 / 24/01/14 page 9/10 AS3935-AN09 Keychain Reference Design Copyright Copyright © 1997-2012, ams AG, Tobelbader Strasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by ams AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by ams AG is believed to be correct and accurate. However, ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services. Note: This product is intended to be used as an early warning indicator for lightning related storms. It does not guarantee accuracy or predict exact strike locations. By using the part, the user shall be aware that he cannot just rely on the indication in order to prevent accidents caused by lightning strikes. ams expressly states that the user must follow the generally known and recommended instructions how to behave in the event of lightning strikes. In no event shall ams or its suppliers be liable for any direct, indirect, incidental, special, exemplary or consequential damages (including, but not limited to procurement of substitute goods or services, loss of use, data or profits, or business interruption) arising out of user´s disregarding of such warnings and instructions. www.ams.com Revision 1.0 / 24/01/14 page 10/10