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USING THE DATA SQUELCH CIRCUIT
A data squelch circuit is provided on the receiver development board. This circuit
is used to add both hysteresis and squelching capabilities as detailed in the ES
Series Receiver Data Guide. Since the ES Series receiver output is not internally
squelched, its output will continually hash when no transmission is present. This
can cause interrupts and buffer overflows in external circuitry. A squelch circuit
helps to eliminate hashing by providing a qualification threshold for incoming
data based on signal strength. This circuit is not a substitute for robust protocol
HOST INTERFACE MODULE
The ES Master Development System features a
Host Interface socket, which allows the use of
two different PC interface modules. The first is a
USB interface module that uses a standard USB
cable (not included) to connect to a PC’s USB
port or a USB hub. The second type of module
is a RS-232 interface module that can be
since squelch can be broken by unintended interference.
To get a better idea of the circuit’s operation, clip an oscilloscope probe on both
RX DATA and SQ. DATA (Squelch Data). With the transmitter off, the SQ. DATA
line will be high (which means that the output is squelched) while RX DATA will
be switching randomly. Squelching is accomplished by comparing RSSI with a
voltage reference created by R17 (potentiometer), R18, and R21. When the
RSSI falls below the voltage set by this reference, the output of the comparator
connected to a standard serial COM port on a
PC using a straight-through 9-pin extension
cable (not included). The evaluation board is
considered a DCE device and as such is
designed to be connected using a straight-thru
serial extension cable. Do not use a null-modem
cable as the boards will not function.
USB Interface Module
Module match. The USB jack or the D-sub
the jumpers on the header as shown in the
adjacent figure. This routes the module's data lines
electrically interfaced, appropriate protocol must be
employed to ensure reliable and error-free data
(U6) will pull to ground. This will disable the data slicer created with the additional
comparator contained within U6. It may be helpful to refer to the schematic
contained later in this document in order to better understand the entire function
of this circuit.
The squelch circuit will be at its factory default setting until the user adjusts it.
Remember that setting a higher squelch threshold can have a severe impact on
range. The squelch level affects only the threshold of the data going to the RS-
232 serial port and the SQ DATA line on TS2.
To set squelch, verify that the transmitter is off and turn on the receiver. Place
an oscilloscope probe on the SQ DATA line, and adjust R17 until SQ DATA
remains high. Two resistors (R27 and R28) are used to connect the module to
the squelch circuit. These may be removed to disconnect the squelch circuit and
prevent it from slightly loading the AUDIO and AUDIO REF lines.
USING THE ENCODER AND DECODER
The MS Series encoder and decoder use a 24-bit address to provide uniqueness
to the transmission and to prevent unintended activation. The development
boards come with a default address. To create a new address, press and hold
the CREATE button on the transmitter board. The address is randomized for as
long as the button is held down. Once released, the MODE_IND LED begins
flashing to indicate that the encoder is ready to accept Control Permissions.
Press the Buzzer and/or Relay buttons to indicate to the encoder that they will
be used. Press the Create button again to exit Create Mode, or let the encoder
time out after 15 seconds.
On the decoder board, press the LEARN button and the MODE_IND LED begins
flashing to indicate that the decoder is ready to learn a new address. Press one
of the authorized buttons on the transmitter board to send a signal. Press the
LEARN button again to exit Learn Mode, or let the decoder time out after 17
seconds and the system is ready for use.
The encoder and decoder can operate on one of four different baud rates as set
by the Baud Rate Selector switches. A faster baud rate will give a faster
response time. Please see the encoder or decoder data guide for the correct
settings. If the switch is up then it is connected to Vcc, if it is down then it is
connected to GND.
Page 6
To install, select the module to be used and then
line up the pins on the module with the headers
on the board. Verify that the pin one polarity
marks on the board and on the Host Interface
RS232 Interface Module
connector should face away from the board. Figure 5: Host Interface Modules
Press firmly on the module so that it slides fully
into the header.
The development system may be prepared for host T S 1 T S 2
operation with the supplied Linx software by setting PDN ENC S Q. DATA
TX PDN NC
PDN R S 2 3 2 AUDIO REF
TX R S 2 3 2 AUDIO
TX DATA R SS I
to the Host Interface Module. Despite being TX ENCODER RX DATA
/CLK RX DECODER
/CLK S EL RX PDN
LO V DET
NC
transfer since the ES Series modules do not GND
encode or packetize the data in any manner. It is TX RX
important to understand that the development Figure 6: Jumper Configuration
boards are transparent; that is, the user's software
is entirely responsible for controlling the timing and error correction aspects of
the link. The evaluation boards have no provision to check or qualify the
incoming data. When designing a protocol to transfer data across a wireless link,
it is very important to remember that interference is inevitable. The protocol must
support error detection and correction if it is to be successful. A correctly
designed protocol will provide optimum performance and throughput for product-
specific applications while taking into account the timing and data-rate
requirements of the module. For further information on protocol considerations
please refer to Application Note AN-00160.
If the designer needs to develop protocols using a physical implementation other
than an RS-232 or USB interface, the designer can build the custom interface
circuitry in the prototyping area and route the module's data signals from the
header to the prototyping area.
Page 7
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相关PDF资料
MDEV-900-HP3-PPS-RS232
KIT MASTER 900MHZ HP-3 SIP RS232
MDEV-900-HP3-SPS-USB
KIT MASTER 900MHZ HP-3 USB SMD
MDEV-900-NT
TRM 900 NT MASTER DEV SYSTEM
MDEV-GPS-SG
KIT MASTER DEV GPS SG SERIES
MDEV-GPS-SR
KIT MASTER DEV GPS SR SERIES
MDEV-LICAL-HS-ES
KIT MASTER DEV HS ES RF MODULES
MDEV-USB-QS
KIT DEV MASTER USB QS SERIES
MF11-0010005
THERMISTOR NTC 100OHM -+5% PROBE
相关代理商/技术参数
MDEV-900-HP3-PPS-RS232
功能描述:KIT MASTER 900MHZ HP-3 SIP RS232 RoHS:否 类别:RF/IF 和 RFID >> RF 评估和开发套件，板 系列:HP3 标准包装:1 系列:- 类型:GPS 接收器 频率:1575MHz 适用于相关产品:- 已供物品:模块 其它名称:SER3796
MDEV-900HP3PPS-RS232
功能描述:射频开发工具 HP-3 Master Dev Sys Pinned, RS232 Module
RoHS:否 制造商:Taiyo Yuden 产品:Wireless Modules 类型:Wireless Audio 工具用于评估:WYSAAVDX7 频率: 工作电源电压:3.4 V to 5.5 V
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功能描述:射频开发工具 HP-3 Master Dev Sys Pinned, USB Module
RoHS:否 制造商:Taiyo Yuden 产品:Wireless Modules 类型:Wireless Audio 工具用于评估:WYSAAVDX7 频率: 工作电源电压:3.4 V to 5.5 V
MDEV-900-HP3-SPS-RS232
功能描述:KIT MASTER 900MHZ HP-3 RS232 SMD RoHS:是 类别:RF/IF 和 RFID >> RF 评估和开发套件，板 系列:- 标准包装:1 系列:- 类型:GPS 接收器 频率:1575MHz 适用于相关产品:- 已供物品:模块 其它名称:SER3796
MDEV-900HP3SPS-RS232
功能描述:射频开发工具 HP-3 Master Dev Sys SMD, RS232 Module
RoHS:否 制造商:Taiyo Yuden 产品:Wireless Modules 类型:Wireless Audio 工具用于评估:WYSAAVDX7 频率: 工作电源电压:3.4 V to 5.5 V
MDEV-900-HP3-SPS-USB
功能描述:射频开发工具 HP-3 Master Dev Sys SMD, USB Module
RoHS:否 制造商:Taiyo Yuden 产品:Wireless Modules 类型:Wireless Audio 工具用于评估:WYSAAVDX7 频率: 工作电源电压:3.4 V to 5.5 V
MDEV-900-NT
功能描述:射频开发工具 NT Series Dev kit w/ Transparent module
RoHS:否 制造商:Taiyo Yuden 产品:Wireless Modules 类型:Wireless Audio 工具用于评估:WYSAAVDX7 频率: 工作电源电压:3.4 V to 5.5 V
MDEV-900-TT
制造商:Linx Technologies Inc 功能描述:TRM 900 TT MASTER DEV SYSTEM 制造商:Linx Technologies Inc 功能描述:RF Development Tools TT Series Master Development System