CIRCUIT DESIGN MU-D1-R User manual

OG_MU-D1-R_v10e
OPERATION GUIDE
Embedded low power radio modem
MU-D1-R 915MHz
Operation Guide
Version 1.0 (Dec. 2010)
CIRCUIT DESIGN, INC.
7557-1 Hotaka, Azumino
Nagano 399-8303, JAPAN
Tel: [phone]
Fax: [phone]
E-mail: [email protected]
Web site: http://www.circuitdesign.jp

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OPERATION GUIDE
Chapter 1 The MU-D1-R 4
1.1 Outline 4
1.1.1 Features 4
1.1.2 Applications 4
1.2 Block Diagram 5
1.3 Example of the Control Method 6
1.3.1 Example 1: Controlling the MU-D1-R with the on-board CPU 6
1.3.2 Example 2: Controlling the MU-D1-R via RS232C 6
Chapter 2 Specifications and Diagram 7
2.1 Main Specifications 7
2.1.1 General specifications 7
2.1.2 UART interface specifications 7
2.2 Terminal Specifications 8
2.3 Channel Table 10
2.4 Dimensional Drawing 11
2.4.1 External dimensions 11
2.4.2 Diagram of dimensions for hole positions 11
Chapter 3 How to Design a User System 12
3.1 Circuit Board Design 12
3.3 The Antenna 13
3.4 Miscellaneous 13
Chapter 4 How to Use the MU-D1-R 14
4.1 Communication Concept 14
4.1.1 Station types and link parameters 14
4.1.2 Basic data transmission 15
4.1.3 The link parameters 15
4.1.4 Conditions for establishing a link 16
4.2 System Configuration 17
4.2.1 Communication within a group 17
4.3 Modes 18
4.3.1 Command mode 18
4.3.2 Text mode 18
4.3.3 Binary mode 18
4.3.4 Mode setting 19
4.4 Resetting 20
4.5 Initializing 20
4.6 Power amplifier On/Off setting 20
Chapter 5 Commands, Responses and Receives 21
5.1 About the Commands, Responses and Receives 21
5.2 Command, Response and Receive Table 23
5.2.1 Data transmit command and data transmit response 23
5.2.2 Data receives 23
5.2.3 Control commands and control responses 23
5.2.4 Monitor commands and monitor responses 24
5.2.5 Test commands and test responses 24
5.2.6 Receive response 24
5.2.7 Error response 24
5.3 Save Setting Command Options 24
5.4 Command, Response and Receive Details 26
5.4.1 Data transmit command, response and data receive 26
5.4.1.1 @DT Data transmit command 1 27
Contents

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5.4.2 Control commands and control responses 28
5.4.2.1 @BR UART baud rate setting 28
5.4.2.2 @CH Frequency channel setting 28
5.4.2.3 @DI Destination ID setting 29
5.4.2.4 @EI Equipment ID setting 29
5.4.2.5 @GI Group ID setting 29
5.4.2.6 @IZ Initialize 29
5.4.2.7 @MD Operation mode register setting 29
5.4.2.8 @PB UART parity bit setting 30
5.4.2.9 @PA Power amplifier On/Off setting 30
5.4.2.10 @PW Antenna power setting 30
5.4.2.11 @RM Response display mode 30
5.4.2.12 @SB UART stop bit setting 30
5.4.2.13 @SR Show serial number 31
5.4.2.14 @SR Reset 31
5.4.2.15 @TB Time without input in the binary mode setting 31
5.4.2.16 @TC Command mode input waiting time 31
5.4.2.17 @UI User ID setting 31
5.4.2.18 @VR Display program version 32
5.4.3 Monitor commands and responses 32
5.4.3.1 @RA RSSI absolute value measurement 32
5.4.3.2 @RC All channel RSSI absolute level measurement 32
5.4.4 Test commands and test responses 33
5.4.4.1 @CT Test data transmission 33
5.4.4.2 @CP Packet test 33
5.4.5 Receive response 34
5.4.6 Error response 34
Chapter 6 How to Develop a Program 36
6.1 Outline of User Processes 36
6.2 The Operations of the MU-D1-R 37
6.3 Command Transmission 38
6.3.1 Issuing commands 38
6.3.2 Issuing data transmission command 38
6.3.3 Issuing commands continuously 39
6.3.4 Issuing commands continuously (when ignoring the response) 39
6.4 Response Processing 40
6.4.1 Responses and receives 40
6.4.2 Response and receive formats 40
6.4.3 Response and receive types 40
6.4.4 Response and receive processing 41
6.5 Assessing the Field Status for Communication 43
6.5.1 Source station RSSI measurement 43
6.5.2 Packet test 43
6.6 Achieving Data Transmission 44
6.7 Operation in Binary Mode 45
6.7.1 Modes 45
6.7.2 When developing a new system 46
6.7.3 When using only the data line of existing equipment 47
6.7.4 Conditions for use of the binary mode 47
Chapter 7 Timing 48
Chapter 8 Evaluation using HyperTerminal 51
Chapter 9 Regulatory Compliance 52

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OPERATION GUIDE
The MU-D1-R is an FCC part15 compliant embedded low power radio modem for transmission of serial data. Since
it is possible to control the radio component using dedicated simple commands, the user can concentrate on
developing the transmitting and receiving programs for their system.
The commands of MU-D1-R are compatible with the commands used for Circuit Design’s MU-1 and MU-2 series.
Transmitting and receiving data and issuing commands are performed using a UART*
1
interface with a single-chip
CPU and the modem can also be controlled via the COM port (RS232C format) of the computer, making it possible
for the user to develop systems quickly*
2
.
The receiving part contains two independent receivers and operates as a true diversity receiver which provides
stable receiving performance even in proximity operation prone to multipath effect.
The MU-D1-R is designed to minimize design difficulties involving high frequency components, so that the user can
embed the modem in their system with peace of mind.
Important
It is not possible simply to replace communication using existing RS232C system equipment connected
with a cable, with MU-D1-R wireless communication. In order to build wireless systems, issues specific to
radio communications must be solved. The hardware and software must be newly designed specifically
for the MU-D1-R.
*1 UART (Universal Asynchronous Receiver Transmitter)
*2 The RS232C interface board with a D-Sub 9-pin connector is available
1.1.1 Features
 FCC part15.247 compliant
 Command compatible with the MU-1 and MU-2 series
 Serial data can be transmitted with a simple system of commands.
 Offers a wide communication range with stable operation.
 The true diversity receiving system achieves stable communication
 The transceiver function is incorporated within a compact unit.
 Ideal for battery operated applications thanks to operation at low voltage and low consumption current.
 Uses the UART interface commonly available with on-board CPUs.
 The high frequency circuit is designed specifically as an embedded radio unit, to operate stably on the user
system circuit board.
 1:1, 1:N, and N:N systems can be built by flexibly setting link parameters.
 It is possible to assess locally the status of radio waves and field noise at the source station.
 RF power selectable by switching the power amplifier ON/OFF (40 mW / 8 mW)
 Using a TCXO in the control part achieves a wide operating temperature range from -20 ºC to 65 ºC
1.1.2 Applications
 Serial data transmission
Energy monitoring, data monitoring devices, handy terminals, barcode readers, housing equipment control
 Telecontrol
Various warning systems, remote control for construction machinery, display devices, motor control, lifters
Remote control of FA equipment
 Telemetry
Security systems, water level monitors for rivers and dams, temperature and humidity gauges, rain gauges,
pressure gauges, voltmeters, ampere meters
Chapter 1 The MU-D1-R
1.1 Outline

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OPERATION GUIDE
Control
CPU
BPF
SAW Filter
EEPROM
14
13
9
10
11
12
8
7
6
5
4
3
2
1
MU-D1-R 915MHz Block Diagram
DAT (NC)
TXL (TX-LED)
RXA (RX-LED)
TE1 (NC)
RST (RESET)
INI
MOD (MODE)
CTS
RTS
RXD
TXD
VCC
GND
RF
Chip select
Port
RXD
TXD
RESET
Port
Port
Port
Ports
RXD
Port
Note SAW: Surface Acoustic Wave
λ /4
Antenna
Port
Port
DVCC for Digital parts
Regulator
3.8v for Power AMP
RF IC
IRQ-TXEN
CLK
ANT_N
ANT_P
MISO
TCXO
Clock
RF
λ /4
Antenna
RF SW RF SW
RF Power
AMP
RF IC
ANT_N
ANT_P
CLK
16MHz
Regulator
2.5v for RFIC
MISO
IRQ-TXEN
SYSCLK
MOSI
MOSI
SELECT
SELECT
Port
Port
16MHz
Ports
RXB (RX-LED)
Port
Port
1.2 Block Diagram

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The VCC terminal of the MU-D1-R is connected directly to the power source of the mounted CPU. Ensure that the
voltage of the power supply is regulated to within DC +4.0 v to +5.0 v.
Basically the MU-D1-R uses hardware flow control with RTS or CTS, however 3-line control can be used without the
hardware flow control. In this case, set the CTS terminal to Low level. In addition, care is required with the timing of
transmitting and receiving.
Example 1 and Example 2 are basically the same methods except for the difference in control voltage.
1.3.1 Example 1: Controlling the MU-D1-R with the on-board CPU
It is possible to interface the MU-D1-R directly using the UART interface of the on-board CPU.
RXD
TXD
CTS(Port)
RTS(Port)
Port
User CPU
With UART
Peripheral
DC +4.0v to +5.0v
Regulator
+
-+4.0v to +5.0v
DC Power
Tx, RX-A, RX-B I dicator
A te aA
MU-D1-R
TXD 1
RXD 2
RTS 3
CTS 4
MOD 5
INI 6
RST 7
NC 8
9 NC
10 RXB
11 TXL
12 RXA
13 VCC
14 GND
A
AA
A
B
BB
B
A te aB
1.3.2 Example 2: Controlling the MU-D1-R via RS232C
1. Using the RS232 port of your computer, you can develop a new program for OS’s such as Windows and the like.
In this case, use an RS232C transceiver. (The program for existing system equipment will not work.)
2. By supplying power to the MU-D1-R with a cable, you can also isolate the radio component from your system and
locate it in the most suitable environment. The distance can be extended by 15 m to 50 m, but the exact distance
should be confirmed through experiments.
* It is also possible to supply power using the No.1 pin of the D-Sub-connector.
1.3 Example of the Control Method

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OPERATION GUIDE
2.1.1 General specifications
Temperature conditions: +25ºC ± 5ºC, typical
Item Specification (Typ.) Remarks
Compatible standards FCC part15.247
Emission class G1D
Antenna power (selectable) 40 mW (PA ON)
8 mW (PA OFF)
+5ºC to +35ºC Contact (50 Ω)
Selectable by the command
Frequency stability Within ± 4 ppm Reference freq. at 25ºC
Antenna 1/4λwire antenna Gain of 2.14 dBi or less
Communication method Half-duplex or one-way
Modulation system BPSK
Oscillation system PLL synthesizer system
Radio communication speed 600 kbps 40 kbps x 15 chips
Frequency range 905.5 MHz to 924.5 MHz
Channel spacing
1 MHz
Number of channels
20
Reception system True diversity
Receiver spurious radiation -54 dBm or less > 960 MHz
Receiver sensitivity -90 dBm Packet error rate 0.1%
(255 bytes/1 packet)
Operating temperature -20ºC to +65ºC
(No dew condensation)
The range varies with the temperature
conditions.
Storage temperature -25ºC to +70ºC
(No dew condensation)
Operating voltage 4.0 V to 5.0 V Absolute maximum rated voltage 5.5 v
Consumption current PA ON : TX 130 mA RX 58 mA
PA OFF: TX 55 mA RX 58 mA When the supply voltage is 5 v
Number of EEPROM conversions 100,000 times Data storage time: About 10 years
External dimensions 36 mm × 26 mm × 8 mm (W × D × H)
Not including the antenna.
H is the height from the mounting
surface.
Unit weight 13 g Not including the antennas
Reference data
* Effective radio communication speed: About 30.1 kbps / Conditions: One-way communication, 25ºC
* Range: About 300 m at 8mW / Conditions: One-way communication, 25ºC, line of sight distance, ground level of 1.5 m, vertical
antenna
2.1.2 UART interface specifications
Communication method Serial communication (RS232C format)
Synchronization Start-stop (asynchronous)
Data speed 19,200 / 38,400 / 57,600 bps
Flow control RTS/CTS hardware flow control
Other parameters Data length (8 bits), Parity (None, Even, Odd), Stop bits (1 or 2 )
Chapter 2 Specifications and Diagram
2.1 Main Specifications

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The MU-D1-R transmits user data in serial data format using
the UART input/output port (TXD terminal and RXD terminal).
Level conversion is required for connection to RS232. The
RS232C DSR signal must be supported by the user's circuit
board.
 The function of each terminal is shown in the table below.
Unused terminals should be set to open.
The control CPU used with this equipment is the NEC
µPD78F0537GA with a CMOS structure. The thresholds for
Low level and High level are V
DD
× 0.2 and V
DD
× 0.8
respectively, based on the supply voltage V
DD
.
Terminal
No.
Terminal
name
I/
O
Description Internal circuit
1 TXD O
The serial data transmit terminal.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
2 RXD I
The serial data receive terminal.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
3 RTS O
The hardware flow control signal output terminal.
If the internal status is not busy, the status is Low
and data can be received via the RXD terminal. If
the internal status is busy, the status is High and
data cannot be received.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
4 CTS I
The hardware flow control signal input terminal.
Determines that the unit is not busy when the
status is Low, and sends data from the TXD
terminal.
Determines that the unit is busy when the status is
High, and does not send data.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
5 MOD
(MODE) I
Switches between the command mode, binary
mode, or text mode.
In the command mode when set to High, and the
binary mode or text mode when set to Low.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
2.2 Terminal Specifications
MU-D1-R Terminal name, Terminal No. (Top view)

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Terminal
No.
Terminal
name I/O
Description Internal circuit
6 INI
(INITIALIZE)
I
The terminal for initializing the CPU internal
settings.
The settings are initialized if the power is turned
on in the Low state. The default values are
enabled when the power is switched on again.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
7 RST
(RESET) I
The CPU reset terminal.
Setting this terminal to Low level for a period of 1
ms resets the internal CPU.
This should normally be set to open.
47ｋΩ
Ｖｃｃ
CPU Reset
Terminal
47ｋΩ
Ｖｃｃ
1kΩ
8 NC
O
A test terminal used at the factory. Normally this
should be open.
470Ω
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
9 NC O
A test terminal used at the factory. Normally this
should be open.
1kΩ
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
10 RXB
(B-RX-LED)
O
The terminal for the receiving monitor LED of the
antenna B. On when valid data is received.
The signal line includes a 1 kΩinternal resistor.
With external resistors, ensure that the LED
current is within 1 mA.
In addition, add a 470 pF multilayer ceramic
capacitor in parallel with the LED.
1kΩ
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
11 TXL
(TX-LED)
O
The terminal for the transmission monitor LED.
On when data is transmitted.
The signal line includes an internal 1 kΩresistor.
With external resistors, ensure that the LED
current is within 1 mA.
In addition, add a 470 pF multilayer ceramic
capacitor in parallel with the LED.
1kΩ
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
12 RXA
(A-RX-LED)
O
The terminal for the receiving monitor LED of the
antenna A. On when valid data is received.
The signal line includes a 1 kΩinternal resistor.
With external resistors, ensure that the LED
current is within 1 mA.
In addition, add a 470 pF multilayer ceramic
capacitor in parallel with the LED.
1kΩ
47ｋΩ
Ｖｃｃ
CPU Port
Terminal
13 VCC I
The power supply terminal. Provide a regulated
power source with a supply voltage of DC +4.0 V
to +5.0 or less.
Applying a voltage higher than the rating will
damage the semiconductor of the unit.
14 GND I GND
- RF A I/O
The antenna terminal for transmission/reception.
- RF B I/O
The antenna terminal for reception.
* The terminal specifications may change without prior notice.

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OPERATION GUIDE
The frequency channels that the MU-D1-R can use are channels 1 to 20 in the 915 MHz band.
To set the channel, use the command format ‘@CH + channel number’.
Example: Set channel 15 as the channel to use.
Specify the channel following ‘@CH’ with 2 ASCII (hexadecimal) characters.
Control command: @CH 0F C R L F
Control response: * CH = 0F C R L F
* : Default channel
MU-D1-R 915 MHz
Channel Frequency Channel Frequency
Dec. (Hex) MHz Dec. (Hex) MHz
1(01) 905.5 11(0B) 915.5
2(02) 906.5 12(0C) 916.5
3(03) 907.5 13(0D) 917.5
4(04) 908.5 14(0E) 918.5
5(05) 909.5 15(0F) 919.5
6(06) 910.5 16(10) 920.5
7(07) 911.5 17(11) 921.5
8(08) 912.5 18(12) 922.5
9(09) 913.5 19(13) 923.5
10(0A) 914.5 20(14) 924.5
2.3 Channel Table

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 2.4.1 External dimensions
2.4.2 Diagram of dimensions for hole positions
Top view
2.4 Dimensional Drawing

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OPERATION GUIDE
When embedding this unit in a user system, pay due attention to the design of the board and case.
1. The power supply used for the MU-D1-R must be a DC regulated power source, with a voltage span of +4.0 v
to +5.0 v. A current of about 130 mA (55 mA with PA OFF) is required when transmitting. Ensure that the voltage
of the MU-D1-R and user system CPU are the same.
Although a regulated voltage is supplied to the internal high frequency component, in order to support the
voltages of a variety of user systems, the power supply for the CPU is connected directly to the VCC terminal. For
this reason, care is required to achieve the correct voltage range.
2. Add a 1 kΩresistor or 0.33 µH inductor to the UART related control signal line. This should be inserted close to
the connector pins.
3. When attaching this unit to a circuit board, use a double sided circuit board if possible. On the top surface of the
board, make a sufficient area beneath the MU-D1-R for the ground pattern (GND plane), and use the bottom
surface of the board for signal lines. For an explanation of the reason for this, refer to “The Antenna” below.
4. If the MU-D1-R power supply line is used jointly with the power supply lines of other circuits in the system (such as
the CPU), it may cause malfunctions, and the unit may not perform properly.
For the power supply of the MU-D1-R, always use a separate line from the system power circuit, and install
bypass capacitors at the receiving point. The bypass capacitors should be an electrolytic capacitor with a volume
of about 220 µF, and a multilayer ceramic capacitor of 470 pF.
5. Add a resistor close to the connector pins of the LED terminal, and limit the LED current to 1 mA or less. This
terminal has an internal 1 kΩresistor in series. If the LED is not sufficiently bright, provide a driver circuit.
Add multilayer ceramic capacitors of about 100 to 470 pF in parallel to the LEDs connected to the TX-LED,
A-RX-LED and B-RX-LED terminals.
6. Make the signal lines to this unit as short as possible.
3.1 Circuit Board Design
Chapter 3 How to Design a User System
RXD
TXD
CTS(Port)
RTS(Port)
Port
User CPU
With UART
Peripheral
DC +4.0v to +5.0v
Regulator
+
- +4.0v to +5.0v
DC Power
T
o
M
U
-
D
1
-
R
470pF
ＶＣＣ
ＧＮＤ
470pF
To u er part
To u er part
1kΩ
220μＦ
470pF
AntennaA
Tx, RX-A, RX-B Indicator
AntennaB
MU-D1-R
TXD 1
RXD 2
RTS 3
CTS 4
MOD 5
INI 6
RST 7
NC 8
9 NC
10 RXB
11 TXL
12 RXA
13 VCC
14 GND
A
AA
A
B
BB
B
GND Plane
GND PlaneGND Plane
GND Plane

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OPERATION GUIDE
In systems where a non-directional antenna is required, it is important that the antenna stands vertically in order to
exploit communication performance to the maximum.
Note that if, for reasons peculiar to the equipment, the antenna must be inside the case, communication
performance will be very significantly degraded when handled in the following ways, since these methods
contravene antenna theory. It is the responsibility of the user to test performance thoroughly when designing
equipment.
1. Putting the antenna inside a metal case
2. Wrapping the antenna around the MU-D1-R itself
3. Locating the antenna beside the ground pattern of your circuit board
4. Fitting the antenna inside by bending it
5. Cutting the antenna to make it shorter
6. Placing the antenna A and B close to each other
The antenna of the MU-D1-R is a 915 MHz band 1/4λwhip antenna. Whip antennas are antennas that substitute the
ground as one end of a dipole antenna. For this reason the ground plays a very important role. Although the main
unit of the MU-D1-R has the function of a ground, in order to exploit its performance fully, connect it to the largest
possible ground pattern when mounting the MU-D1-R on your circuit board.
The antenna A and B should be kept apart as much as possible. If the antennas are crossed over each other, one
may be affected by another and full performance of true diversity may not be reached.
In addition, for two-way communication between fixed stations, inclining the whip antenna of the MU-D1-R forwards
may increase its communication range. Carry out tests in the specific environment of use.
1. Devise ways of isolating the MU-D1-R as far as possible from sources of noise, including from other embedded
equipment.
2. Arrange the MU-D1-R so that it will not be covered by the operator’s hand or the like.
3. The MU-D1-R does not have a waterproof structure. If the antenna is located outside the main unit, use a
structure that prevents water droplets from entering the case.
3.2 The Antenna
3.3 Miscellaneous

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4.1.1 Station types and link parameters
When performing communication using the MU-D1-R, the source station transmits data towards the target station.
To avoid collisions with, and to ensure independence from other systems, it is necessary to set the link parameters
to identify the system and each station.
Group ID 01
Same area
UI = 0055
GI = 01
Source station
EI = 01
03
Target station
02
Group ID 02
Group ID 03
User ID 0055
UI = 0055
GI = 01
01
EI = 02
UI = 0055
GI = 01
EI = 03
Destination ID: DI
User ID: UI
Group ID: GI
Equipment ID: EI
Channel: CH CH = 08 CH = 08 CH = 08
Channel 08
Target station
1. The source station and target station
• Source station The station that transmits data
• Target station The station that receives data. The target station outputs the received data to the user controller.
2. The link parameter
In order to establish communication between the radio stations, it is necessary first to set the link parameters.
• UI: User ID
An ID given to the MU-D1-R user for identification of the user.
If all the equipment within the user system is not set to the same User ID, no link will be made.
• GI: Group ID
An ID to identify the group within the user system. Set the same Group ID for all radio stations within the group.
• EI: Equipment ID
An ID given to each unit for identification of each station. The data transmit command transmits data to the
Equipment ID set as the Destination ID
• DI: Destination ID
Specifies the Equipment ID of the target station.
• Channel
If all stations in a system are not set to the same channel, no link will be made.
4.1 Communication Concept
Chapter 4 How to Use the MU-D1-R

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4.1.2 Basic data transmission
When user data is transmitted from the source station towards the target station using data transmit 1 command,
a character string including the data (data receive 1) is output from the target station and processed by the
program of the user controller.
Example 1:1 (1:N) system
When the source station 5F transmits the 5 bytes of data ‘ABCDE’ to the target station 01
User
controller
DI=01
⑥ Send data
・Initial setting
④ Issue the data transmit command1
⑤ Data transmit response
・Target station 01 status
Source station
EI=5F
Target station
EI=01
User
controller
@DT 05 AB DE R L F
＊DT=05 R L F
＊DR=05 AB DE R L F
⑦ Data receive1
④
⑤⑦
⑥ Send data
③ Set the Destination ID (DI)
① Set all stations to the
same User ID, Group ID and
channel.
②
Set a different number to
each equipment as the
Equipment ID(EI)
・Souce station 5F status
4.1.3 The link parameters
In order to transmit and receive data, the MU-D1-R has the following link related parameters.
Link parameters can be specified easily with commands, and they can be changed each time data is sent.
In addition, if the source station and target station do not all use the same channel, no link will be made.
1. UI: User ID, 16-bit, 0000h to FFFEh (0000h is the ID for testing, and FFFFh cannot be used)
The User ID is an ID given to the MU-D1-R user for identification of the user system. Communication is not
possible unless all equipment within the user system is set with the same User ID. If a user configures
multiple systems, use the Group ID for identification. The User ID setting command is ‘@UI + User ID +
password’. The product default User ID is 0000 and this can be used as it is when no particular User ID is
required. However, we recommend that you set a User ID to prevent radio interference within a given area.
If you require a User ID, please contact Circuit Design, Inc. The 16 User IDs listed in the explanation of User ID
command can be used freely.
2. GI: Group ID, 8-bit, 00h to FFh
The Group ID is an ID to identify the group within the user system. Set the same Group ID for all equipment
within the group. Maintain Group IDs as identification numbers when building other systems. The setting
command is ‘@GI’.
Please contact Circuit Design, Inc. in cases where use of Group IDs is insufficient and you require other User
IDs.
3. EI: Equipment ID, 8-bit, 01h to FFh (FFh is a special operation)
The Equipment ID is an ID for identification of each radio unit. At the source station, enter the Equipment ID of
the target station as the Destination ID to which to transmit data.
At the target station, the Destination ID included in the received packets is automatically compared with the local
station EI. The setting command is ‘@EI’.
4. DI: Destination ID, 8-bit, 00h to FFh (00h and FFh are special operations)
This is used to specify the Equipment ID of the target station. The setting command is ‘@DI’. If 00 (DI = 00h) is
specified as the Destination ID and data transmit command 1 is issued, all equipment within the same group
receives the data at the same time, irrespective of the Equipment ID (Broadcast). If DI = FFh is specified, the
data is sent but no station will receive it.
5. Channel
If all stations in a system are not set to the same channel, no link will be made.

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4.1.4 Conditions for establishing a link
A link is established for communications when the following conditions are met simultaneously.
1. There are no errors in the received packet
2. The User ID and Group ID match
3. The Equipment ID specified as the Destination ID and the Equipment ID of the target station match
4. The channel used is the same

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The MU-D1-R can be used for building 1:1, 1:N, and N:N systems. Several systems can be operated within the
same area by separating the channels used.
Equipment IDs from 01h to FEh can be specified, and a maximum of 254 MU-D1-R units can be connected in 1
group.
4.2.1 Communication within a group (1:N and N:N systems)
Set the same User ID and Group ID for one group. If the Destination ID specified at the source station and the
Equipment ID of the target station match, data (data receive 1) is output from the target station.
The diagram below shows a 1:N system, although it is also possible to build an N:N system in which all the units
have an equal relationship.


Communication between groups
By changing the Group ID for transmitting, it is possible to communicate with another group.


Broadcast communication
If the Destination ID is specified as 00h at the source station and data is transmitted, all target stations will receive
the data at the same time, irrespective of the Equipment ID.
4.2 System Configuration
Group1(1:N system)
Same area
Group2(1:N system)
Group3 (1:N system)
UI = 0055
GI = 01
EI=02
UI = 0055
GI = 01
EI=03
UI = 0055
GI = 01
EI=04
UI = 0055
GI = 01
EI=01
Note: UI = User ID G = Group ID EI = Equipment ID
DI=01
DI=02
DI=03
DI=01
DI=04
DI=01
MUD1-RS2
MUD1-RS2
MUD1-RS2
MUD1-RS2
UI
EI
EI EI
EI
EI
EI EI
EI
GI=8
EI
EI EI
EI
※All equipment in the system has the same frequency channel.
※Communication is not possible between different Group IDs.
EI
EI EI
EI
GI=1GI=1
GI=1
UI User ID 2bytes
Item name Size
0000-FFFE Set a password
ID value Content
GI Group ID 1byte 00 FF No. 0 to 255
EI Equipment ID 1byte 01 FE No. 1 to 254
※Group ID and Equipment ID can be set freely within the range above.

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Note
The MU-D1-R has the following 3 modes.
1. Command mode (standard mode)
2. Text mode (for testing)
3. Binary mode (for testing)
Transmitting and receiving data is usually performed in the command mode. Use this mode when you build your
system. The text mode and binary mode are provided as testing modes, however you can also make applications
within the range of these functions.
When configuring your system, ensure that the source station and target station are in the
same mode.
4.3.1 Command mode
This is the basic mode for sending and receiving user data by radio.
The MU-D1-R commands consist of commands for transmitting and receiving data, and commands for control of
the parameters of the MU-D1-R unit itself. Changing the parameters, mode, and channel of the main unit cannot be
performed in the binary mode or text mode. Consider how to enable mode switching at the hardware design stage.
Control of the radio component is performed automatically by the MU-D1-R, so you do not need to pay attention to
this aspect.
255 bytes of user data can be sent at one time.
For transmission of user system data, the data transmit command 1 is used.
When the MU-D1-R receives data, since only correctly received data is output to the user application as a data
receive, it is processed on the user side properly.
4.3.2 Text mode (for testing)
This mode is used to check operation using RS232C communication software (HyperTerminal and the like) on a
PC.
Text data can be input and output directly. This mode is convenient for transmitting and receiving characters
entered using a keyboard. Always add the C R L F code as a terminator at the end of the character string. When the
MU-D1-R detects this terminator, it starts data transmission. Ensure that the maximum number of characters input
is within 255 bytes. The C R L F code (0Dh, 0Ah) and Esc code (1Bh) cannot be sent by radio. However, the C R L F code
is attached to the end of the data output from the target station as a terminator.
4.3.3 Binary mode (for testing)
This mode is used to check operation using RS232C communication software (HyperTerminal and the like) on a
PC.
All 8-bit codes (00h to FFh) can be transmitted and received as data. 225 bytes of binary data can be input or output
directly at one time.
The input character string (max. 255 characters) is buffered until the buffer is filled with 255 characters, or until the
value set for the period during which no data is input is reached, and the character string is framed and transmitted.
The setting for the period during which no data is input is performed with the ‘@TB’ command.
4.3 Modes

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4.3.4 Mode setting
When the MODE terminal is at High level
The MU-D1-R is set to the command mode irrespective of the setting in the mode register. The recommended
operation mode of the MU-D1-R is the command mode. When setting the MODE terminal to Low to switch to other
modes, preset the mode register.
When the MODE terminal is at Low level
1. In the command mode if the ‘@MD TX’ command is issued, the MU-D1-R mode register is set to ‘TX’, which is the
text mode. Issuing the ESC code returns from the text mode to the command mode.
2. In the command mode if the ‘@MD BI’ command is issued, the MU-D1-R mode register is set to ‘BI’, which is the
binary mode. To switch from the binary mode to the command mode, turn off the power supply of the MU-D1-R
briefly or reset the hardware.
If the BI mode is fixed in the EEPROM using the command option ‘/W’, the MU-D1-R cannot be set to the
command mode without initializing it.
To initialize the MU-D1-R, set the INI terminal to Low and turn on the power, and after turning off the power briefly,
set the INI terminal to High and turn on the power again.
3. By setting the MODE terminal to High level, the MU-D1-R can be set to the command mode whatever the setting
in the MU-D1-R mode register (irrespective of the current mode).
Mode relationship diagram
M
o
d
e
t
e
r
m
i
n
a
l
l
e
v
e
l
High
Low
Low
@MDTX
MOD terminal
Low
@MDCD
MOD terminal
Low
@MDBI
MOD terminal
MOD terminal
H igh
MOD terminal
H igh
MOD terminal
H igh
Command modeBinary mode Text mode
Command mode
@MDTX@MDBI
1, Reset (RST terminal) *1
2, Initialize (INI terminal) *2
*1: When the mode is set in the RAM *2: When the mode is fixed in the PROM
Mode Register
BI CD TX
1, Issue the SC code
2, Reset (RST terminal) *1
3, Initialize (INI terminal) *2
* BI: Binary mode CD: Command mode TX: Text mode
* The brackets ( ) in the diagram indicate use of an RS232C driver. When using HyperTerminal, the DTR
line is always at H level and the MODE terminal is at L level.

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OPERATION GUIDE
If you are uncertain about the various settings of the MU-D1-R, return them to the settings at the time the power was
turned on.
The internal CPU is reset by any of the following.
1. Set the reset (RST) terminal of the MU-D1-R to 1 ms period Low level.
2. Issue the software reset command ‘@SR’.
3. The target station can be reset using an extended command.
Return the unit to the factory default settings if communication with the MU-D1-R is not possible or if you are
uncertain of the internal settings.
The internal CPU is initialized with any of the following.
1. Set the INI terminal of the MU-D1-R to Low level and turn on the power. Then turn off the power, and after
setting to the INI terminal to open, turn it on again.
2. Issue the initialize command ‘@IZ’. After issuing it, always issue the software reset command ‘@SR’.
After initialization, the main parameter values (default values) are as follows. For details of the default values,
refer to the relevant command in the manual.
1. Link parameters
User ID: UI = 0000, Group ID: GI = 00, Equipment ID: EI = 01, Destination ID: DI = 01, Channel = 1 channel
2. UART parameters
Baud rate = 19,200 bps, parity = none, stop bit = 1, data length = 8 bits
3. Internal operation parameters
Mode = command
The MU-D1-R is equipped with a power amplifier switching function which can switch the antenna power (output
power) between 40 mW and 8 mW. This is useful for setting the antenna power according to the required operation
range and conditions. To switch the power amplifier, issue the ‘@PA’ command.
4.6 Power amplifier On/Off setting
4.4 Resetting
4.5 Initializing