AMS AS3933 Operating and installation instructions

www.ams.com Revision 1.1/ 24/02/13 page 1/20
AS3933
3D Low Frequency Wakeup Receiver
Application Note:
AS3933
-
AN01
–
Demoboard
Description

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 2/20
Table of Contents
1 General Description ............................................................................................................. 4
2 Kit Content ........................................................................................................................... 4
3 Getting Started..................................................................................................................... 4
4 Hardware Description........................................................................................................... 4
4.1 AS3933 Demoboard............................................................................................................. 4
4.2 125kHz Wake-up Transmitter Board.................................................................................... 6
5 Software Description............................................................................................................ 7
5.1 Installing the GUI..................................................................................................................7
5.2 Description of the GUI of the Receiver ................................................................................8
5.2.1 Channel Enable.................................................................................................................... 8
5.2.2 Low Power Mode ................................................................................................................. 8
5.2.3 Clock Generator................................................................................................................... 9
5.2.4 Calibrate RC Oscillator ........................................................................................................ 9
5.2.5 Antenna Damper.................................................................................................................. 9
5.2.6 Envelope Detector Time Constant.......................................................................................9
5.2.7 Data Slicer............................................................................................................................ 9
5.2.8 Comparator Hysteresis ........................................................................................................ 9
5.2.9 Gain Reduction .................................................................................................................... 9
5.2.10 Frequency Detection Tolerance.........................................................................................10
5.2.11 General Settings ................................................................................................................10
5.2.12 Wakeup Pattern (Manchester)...........................................................................................10
5.2.13 Correlator ...........................................................................................................................10
5.2.14 Automatic Time-Out...........................................................................................................11
5.2.15 Clear Wake ........................................................................................................................11
5.2.16 Symbol Rate.......................................................................................................................11
5.2.17 Check Resonance Frequency............................................................................................11
5.2.18 Input Capacitor Bank..........................................................................................................11
5.2.19 Artificial Wakeup ................................................................................................................ 11
5.2.20 Clear False Wakeup...........................................................................................................11
5.2.21 Reset RSSI ........................................................................................................................11
5.3 Description of the GUI of the Transmitter ..........................................................................12
5.3.1 Duration of Carrier Burst....................................................................................................12
5.3.2 Number of Preamble Symbols........................................................................................... 12

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 3/20
5.3.3 Symbol Rate.......................................................................................................................12
5.3.4 Enable Buzzer....................................................................................................................13
5.3.5 Wakeup Pattern (Manchester)...........................................................................................13
5.3.6 Manchester Pattern Length................................................................................................13
5.3.7 Correlator ...........................................................................................................................13
6 Board Schematics, Layout and BOM................................................................................. 14
6.1 AS3933 Demoboard Schematic.........................................................................................14
6.2 AS3933 Demoboard Layout...............................................................................................15
6.3 AS3933 Demoboard BOM .................................................................................................16
6.4 125 kHz Wake-up Transmitter Board Schematics.............................................................17
6.5 125 kHz Wake-up Transmitter Board Layout.....................................................................17
6.6 125 kHz Wake-up Transmitter Board BOM ....................................................................... 18
7 Ordering Information.......................................................................................................... 19
Revision History
Revision Date Owner Description
1.0 20.07.2010 JPE Initial release
1.1 24.02.2013 JRY Update to corporate format

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 4/20
1 General Description
With the AS3933 Demoboard it is possible to demonstrate the chip’s features as described in the
AS3933 datasheet. The 125kHz Wake-up Transmitter Board is included to offer the user a complete
system for evaluation purposes. This application note describes the operation of the two boards and
gives details on the hardware and software implemented in the demokit.
2 Kit Content
The kit comprises
•1x 125kHz Wake-up Transmitter Board
•1x AS3933 Demoboard
•2x CR2032 coin cells
•1x USB cable
•1x USB stick
3 Getting Started
•Connect the +9V DC power supply F to the 125kHz Wake-up Transmitter Board.
•Insert the +3V battery at H of the AS3933 Demoboard
•Turn on the AS3933 Demoboard via the ON/OFF-Switch C. All LEDs flash up once.
•Start transmitting wake-up patterns via AUTO E of PATTERN B.
•As soon as the AS3933 Demoboard receives a wake-up pattern the RSSI LEDs flash up for
0.5s and show the momentary received signal strength. At the same time the X, Y, or Z
LED flash up indicating which channel receives the strongest signal.
4 Hardware Description
4.1 AS3933 Demoboard
Figure 1: AS3933 Demoboard Top and Bottom
A
C
D
E
F
H
G

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 5/20
Figure 2: User Interface Description
Label Name Description Info
A BUTTON
Long press (1.5s) tunes
the antenna Each axis (X,Y, and Z) of the LF antenna can be tuned exactly to 125kHz. The resonance
frequency of each channel can be read out via the
GUI.
1x short press reads
the false wake-ups The number of false wake-ups can be read out and displayed via the RSSI-LEDs.
2x short press (double
click) clears the false
wake-ups
Pressing FALSE WAKEUP twice in quick
succession resets the number of false wake-ups.
Each RSSI-LED lights up shortly.
C ON/OFF ON/OFF-Switch Power on/off the Demoboard. Source (battery or
USB) is automatically detected.
G USB-
Connector Mini USB 5-pin Connector USB interface for GUI.
H CR2032
Battery Battery Holder Insert CR2032 coin cell here.
Figure 3: Indication LEDs
LED Color Info
RSSI
(5 bit) Red LEDs Received Signal Strength Indication. Displays the actual received signal strength whenever a WAKEUP occurs. When pressing FALSE WAKEUP
these LEDs display the number of false wake-ups that occurred.
X Red LED Strongest wake-up signal received on channel 1 (X)
Y Red LED Strongest wake-up signal received on channel 2 (Y)
Z Red LED Strongest wake-up signal received on channel 3 (Z)
Figure 4: Jumper Description
Jumper Name Description Info
F IDD Supply
Current The supply current of the AS3933 can be measured here. Set this jumper for normal operation.
D
AS3933 specific outputs
D1 WAKE Wake Output Interrupt
D2 DAT Data Output
D3 CL_DAT Manchester Recovered Clock
E Microcontroller
interface The SDI interface from the microcontroller can be replaced by a proprietary solution
E1 CS Serial Digital Interface Chip Select

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 6/20
Jumper Name Description Info
E2 SCL Serial Digital Interface Clock
E3 SDI Serial Digital Interface Input
E4 SDO Serial Digital Interface Output
E5 GND Ground (0V)
Note: When the AS3933 Demoboard is connected to the GUI it is necessary to RESET the device
by turning the AS3933 off and on via switch C. Another possibility to prepare the Demoboard for
USB connection is to press buttons A and B simultaneously before connecting the USB cable.
4.2 125kHz Wake-up Transmitter Board
Figure 5: 125kHz Wake-up Transmitter Board
Figure 6: User Interface Description
Label Name Description Info
A PATT+DATA Pattern+Data –
Button The transmitter continuously sends the wake-up pattern plus data (01010101).
B PATT Single-Pattern –
Button The transmitter sends a single wake-up pattern.
C AUTO Automatic Pattern –
Button The transmitter sends a wake-up pattern every 1s.
D STOP Stop Pattern –
Button The transmitter stops transmitting.
E USB-
Connector Mini USB 5-pin connector USB interface for the GUI.
F Power Supply +9V/2A DC Power
Supply Insert main power adapter here.
E
A
B
C
D
F

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 7/20
Figure 7: Indication LEDs/ Buzzer
LEDs Color Info
G Buzzer The buzzer signals whenever a wake-up pattern is transmitted. This
feature makes range measurements easier. The buzzer can be disabled
via the GUI.
STANDBY Red
LED Transmitter is on stand-by. No wake-up pattern is sent.
Pattern Red
LED Wake-up pattern is transmitted.
Pattern+Data Red
LED Wake-up pattern plus data is transmitted.
Note: Before connecting the 125kHz Wake-up Transmitter Board to the GUI the transmission of
wake-up patterns needs to be terminated by pressing button D.
5 Software Description
5.1 Installing the GUI
•Execute the AS3933_EvalSW.msi
•Follow the installation guide
•Run the GUI AS3933_EvalSW.exe
Note: Before connecting the 125 kHz Wake-up Transmitter Board to the GUI press button D to stop
transmitting wake-up patterns.

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 8/20
5.2 Description of the GUI of the Receiver
Figure 8: Graphical User Interface of the AS3933 Demoboard
All adjustments can be saved via Store Settings in the lower right corner of the Receiver tab. If all
settings should be reset to the default configuration push the button Preset Default. All
configurations that are set by the GUI correspond to the Register Map of the AS3933. The Register
Map can be viewed via View/Register Map (Ctrl+M). All registers can be updated manually via
File/Readout Registers (Ctrl+R) or the update of the registers is done automatically via
File/Automatic Update (Ctrl+U).
Note: A possible firmware update can be done via Help/Firmware Update (Ctrl+F). Load the latest
*.bin file and update the firmware.
5.2.1 Channel Enable
The AS3933 Demoboard has a three dimensional antenna. Each of the three antenna inputs can be
enabled or disabled.
5.2.2 Low Power Mode
The AS3933 features two low power modes, which can be selected here. By default no power
saving mode is enabled which means that all channels are active all the time. For details on the low
power modes please see the AS3933.

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 9/20
5.2.3 Clock Generator
The clock source for the AS3933 can be selected here. The AS3933 Demoboard has an on-board
crystal oscillator that is used by default. In case the RC oscillator is used it can be calibrated to
achieve a higher precision.
5.2.4 Calibrate RC Oscillator
The RC oscillator can be calibrated via the microcontroller or the LC antenna.
5.2.5 Antenna Damper
The antenna can be damped in order to limit the range. Therefore a resistor inside the AS3933 is
switched into parallel to the antenna. The value of the resistor can be selected between 1kΩto
27kΩ.
5.2.6 Envelope Detector Time Constant
The performance of the Demodulator can be optimized according to the bit rate and preamble
length. For a higher bit rate the time constant needs to decrease. Adjust the Envelope Detector’s
time constant according to your symbol rate. The recommended time constants for different symbol
rates are listed in the datasheet.
5.2.7 Data Slicer
There are two possibilities to set the threshold level for the Data Slicer: the dynamic threshold and
the absolute threshold. The absolute threshold is set by selecting the hard threshold enable bit. In
quit environments (no noise sources present) the absolute threshold can be reduced by additionally
setting the hard threshold reduction bit. The dynamic threshold is enabled automatically when the
hard threshold enable bit is not set.
In case the dynamic threshold is enabled the noise immunity of the Data Slicer can be adjusted via
the Data Slicer time constant. Increasing this time constant will result in improved noise immunity
only if the minimum preamble length is also adjusted. Therefore, it is not possible to select a
specific Data Slicer time constant in the GUI but different minimum preamble lengths. The Data
Slicer’s time constant is internally linked to this setting. The recommended minimum preamble
lengths for different Data Slicer time constants are listed in the datasheet.
5.2.8 Comparator Hysteresis
The Data Slicer’s comparator hysteresis can be adjusted between 20mV and 40mV. Furthermore,
the data slicer hysteresis can be active for either only positive edges or for both (positive and
negative) edges.
5.2.9 Gain Reduction
The Gain Reduction of the channel amplifier can be selected between 0dB up to -24dB. When the
setting AGC UP-DOWN is selected the maximum achievable gain is also defined by this setting.

AS3933-AN01
Demoboard Description
www.ams.com Revision 1.1/ 24/02/13 page 10/20
5.2.10 Frequency Detection Tolerance
The Frequency Detection Tolerance can be tighter or more relaxed. For details please see the
datasheet.
5.2.11 General Settings
•Enable sensitivity boost: The channel amplifier gain is boosted to +3dB.
•AGC only on carrier burst: The automatic gain control is acting only on the first carrier burst.
•AGC UP-DOWN: The automatic gain control is operating in both directions (up and down).
At the beginning the gain of the channel amplifier is set to the maximum and the AGC
reduces it according to the received signal input level. If AGC UP-DOWN is disabled the
AGC can only decrease the gain for the whole duration of the data reception. In this mode
the system holds the RSSI peak.
•Mask data before wakeup: During the pattern correlation it is possible to display the data
(received preamble + pattern) on the DAT pin, if this bit is disabled. Otherwise, this will be
masked. In case the user decides to mask the data before the generation of the interrupt on
the pin WAKE, then the data will be displayed only after the generation of the interrupt.
•Display clock generation: The clock generator output signal is displayed on CL_DAT pin.
5.2.12 Wakeup Pattern (Manchester)
Select the wake-up pattern here. Each field defines 4 bit. If the transmitted pattern matches the
selected pattern, a wake-up interrupt is generated at the WAKE pin. The WAKE pin goes high.
5.2.13 Correlator
•Enable Correlator: If the Correlator is enabled the chip searches first for the preamble bits
and then for data pattern (Manchester encoded wake-up pattern). Should the pattern
correlation be disabled, the AS3933 goes directly into the data receiving mode.
•Enable Manchester decoder: If the Manchester decoder is enabled the data on the DAT pin
can be directly read binary. In addition, the recovered clock is presented on the CL_DAT
pin.
•Manchester Pattern Length: the Manchester pattern length can be selected between 16bit
and 32bit. The possible selection of the wake-up pattern (Manchester) is changed
accordingly.
•16 bit pattern length: Each field of the wake-up pattern defines 4 bit, which are directly
Manchester encoded.
Example: 9 6 6 9 (Manchester) 1001 0110 0110 1001 (binary, Manchester conform);
sum = 16bit
•32 bit pattern length: Each field of the wake-up pattern identifies 4 bit, which are
hexadecimal encoded. Each bit defines one Symbol and is converted to Manchester by the
microcontroller in the second step.
Example: 7 B A 5 (Symbol) 0111 1011 1010 0011 (binary) 10010101 01100101
01100110 10100101 (binary Manchester conform); sum = 32 bit
•Single pattern: The wakeup pattern is sent as single string.