Operation Manual

Application Note: AS3935-AN09 – Keychain Reference
Design
AS3935
AN09-Keychain Reference Design
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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
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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
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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
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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
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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.
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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
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2
3
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D
26.11.2013
Sheet
3
of
3
4
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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
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AS3935-AN09
Keychain Reference Design
7.3
Bill of Materials
Figure 10: AS3935 Franklin Lightning Sensor
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TM
Keychain Reference Design BOM
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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.
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