CIRCUIT DESIGN MU4-USBIF User manual

OG_MU4_USBIF_v10e
OPERATION GUIDE
Embedded low power radio modem MU-4
MU-4 USB Interface Board
MU4-USBIF
Operation Guide
Version 1.0 (Sep. 2020)
CIRCUIT DESIGN, INC.,
7557-1 Hotaka, Hotaka-machi,
Minamiazumi, Nagano 399-8303 JAPAN
Tel: [phone]
Fax: [phone]
E-mail: [email protected]
Web site: https://www.cdt21.com/

OG_MU4-USBIF_v10e 1 Circuit Design, Inc.
OPERATION GUIDE
Chapter 1 The MU4-USBIF 2
1.1 Outline 2
1.2 System Requirements 3
1.3 Product Name and Part Number 4
1.4 Board and contents 4
Chapter 2 The MU4-USB 5
2.1 Part Names and Functions 5
2.2 Block Diagram 6
2.3 Main Specifications 7
2.4 Channel Table 7
2.5 External Dimensions 8
2.6 Circuit Diagram 9
Chapter 3 How to Use the MU4-USB 10
3.1 System Configuration Example 10
3.2 The USB driver 11
3.3 Resetting 11
3.4 Initializing 11
Chapter 4 How to Design a User System 12
4.1 Embedding the Product 12
4.2 The Antenna 13
4.3 Regulatory Compliance 13
4.4 Cautions 13
Chapter 5 How to Develop a Program 13
Chapter 6 When Designing an Original System 14
6.1 The Circuits 14
6.2 The USB Driver 14
6.3 Directly Controlling the USB Chip 15
Contents

OG_MU4-USBIF_v10e 2 Circuit Design, Inc.
OPERATION GUIDE
The MU-4 USB interface board, MU4-USBIF is a development board for planning radio system applications with a
USB interface connection function that use the embedded low power radio modem MU-4. Purchasing the board
enables you to begin evaluating communication with the MU-4 immediately.
The board uses the FTDI FT8U232MB that has a protocol conversion function to convert between the USB and
UART interfaces. Since the control program created by the user accesses the host COM port, users can apply their
fund of knowledge of RS232C technology.
The board with MU-4 can be controlled using simple dedicated commands, so that the developer can concentrate
on designing the protocols for transmitting and receiving data, without needing to be aware of control of the radio
component.
Power to the USB interface board MU4-USBIF is supplied from the USB interface, so an external power supply is
not necessary.
*1 Before using this product, it is first necessary to install the VCP driver. For installation, refer to the information on
installing the driver found in the setup launcher in the zip file.
◼1.1.1 The MU4-USB
In this operation guide, for the sake of convenience, the MU-4 USB interface board MU4-USBIF with the embedded
low power radio modem MU-4 mounted on it is referred to as the MU4-USB. Before using the board, mount the
MU-4 on the MU4-USBIF. When mounting the MU-4, observe the following cautions, and carry out the soldering
carefully.
Cautions for soldering
•Attach the MU-4 unit to the conversion board before mounting it on the MU1-USBIF.
•To prevent damage to the connectors, solder the joints quickly.
•Avoid connection defects.
•In order to prevent damage to the MU-4 and the MU1-USBIF from static electricity, ground
yourself before starting work.
•Do not cause short circuits by dripping solder on the board.
Important
The development board does not include module MU-4. Please make sure to order it if needed.
It is not possible simply to replace communication using existing RS232C system equipment connected
with a cable, with MU4-USB wireless communication. The hardware and software must be designed
specifically for the MU-4.
MU-4-434
-
-
+
Conversion
board
MU4-USB
-
MU1-USBIF
-
+
=
Chapter 1 The MU4-USBIF
1.1 Outline
Caution

OG_MU4-USBIF_v10e 3 Circuit Design, Inc.
OPERATION GUIDE
◼1.1.2 Explanation of terminology
The meaning of the terminology used in this operation guide is as follows.
1. 1. The “Evaluation program and driver” is the zip file that is available from the Circuit Design website, that
contains the setup program, Operation Guide and so on.
The program is located on MU-4 documents page.
2. 2. The “Evaluation Program” is a program for evaluation of the MU-2-R and series of products, called the
MU-2-R Evaluation Software Program MU2-ESP. After installation it is found inside the “Circuit Design” folder
that appears on the desktop of your PC. MU-4 is compatible with commands and interface, also can use this
program.
◼1.1.3 Features
◆Power for the MU4-USB is supplied by the USB interface cable.
◆The COM port used is recognized as a VCP *1, and the user need only create a control program for accessing a
normal COM port.
◆Circuit diagrams for making user systems are publicly available.
◆The product can be embedded in a case, and can be used for making products for radio control from a PC.
◆Compact size (47 × 78 × 16 mm) fits in a small housing.
◆Features of the MU2-ESP evaluation program;
1. You can issue all commands for controlling the interface board with module.
2. There is a test program for checking the communication performance of the interface board with module.
3. There is an air monitor function for checking the status of radio waves in the field.
*1: Recognized as a VCP (virtual COM port) when the dedicated driver is installed.
◼1.1.4 Applications
◆Serial data transmission
Energy monitoring, data monitoring devices, handy terminals, barcode readers
◆Telecontrol
Remote control for construction machinery, display devices, motor control, lifters
Remote control of FA equipment
◆Telemetry
Water level monitors for rivers and dams, temperature and humidity gauges, rain gauges, pressure gauges,
voltmeters, ammeters
Systems used with MU4-USBIF must meet the following conditions.
1. OS: Windows 8 and 10
2. Hard disk capacity: 30 MB or more
3. Memory: 64 MB or more
1.2 System Requirements

OG_MU4-USBIF_v10e 4 Circuit Design, Inc.
OPERATION GUIDE
Product name: MU-4 USB interface board Part number: MU4-USBIF
The board and contents are as follows. First, please check that you have all the items.
◼1.4.1 Accessories
1. USB interface board MU1-USBIF 1
2. Conversion board 1
3. Spacers (used as legs) 10 mm 4
4. Screws for spacers M2.6 × 6 mm 4
MU1-USBIF x 1
-
Conversion board x 1
Screw(M2.6 x 6mm) x 4
Spacer(10mm) x 4
1.3 Product Name and Part Number
1.4 Board and contents

OG_MU4-USBIF_v10e 5 Circuit Design, Inc.
OPERATION GUIDE
[07]λ/4 lead antenna
[09]Power LED
[01]USB-B type receptacle
[02]Initialize button
[03]RX-LED
[04]TX-LED
[05]MU-4
[06]Conversion board
[08]4-mounting holes
RF
GND VCC
RXD CTS
INI
RXM
DO
RXL
TXD
RTS
MOD
RST
DI
TXL
MU-4-434
[01] USB-B receptacle: For connecting the double shield USB cable (USB 2.0 High Speed).
[02] Initialize button:Resets the MU-4 mounted on the MU4-USB to the factory default settings. Follow the
procedure below.
1. Turn on the power (connect the USB cable) while pressing the initialize button.
2. Release the initialize button and after turning off the power (remove the USB cable), turn the power again
(connect the USB cable) after a while (approx. 5 seconds).
[03] RX-LED: On when data is received.
[04] TX-LED: On when data is transmitted.
[05] MU-4: A low power serial data transmission modem.
[06] Conversion board: A board making it possible to fit the pins of the MU-4 into the USB board.
[07] λ/4 lead antenna: A λ/4 long lead antenna. (ANT-LEA-01, ANT-RIG-01-R)
[08] Mounting holes: 3Φholes for mounting
[09] Power LED: The LED comes on when the USB cable is connected.
2.1 Part Names and Functions
Chapter 2 The MU4-USB (MU-4 + MU4-USBIF)

OG_MU4-USBIF_v10e 6 Circuit Design, Inc.
OPERATION GUIDE
λ/4
lead
antenna
Regulator
+3v
Tx
LED
Rx
LED
SW2
USB
Controller
EEPROM
VCC
1
2
3
4
5
6
7
8
+3v +3v
+3v
Power
LED
Power LED
Tx LED
Rx LED
RSSI
GND
GND
+3v
+3v
Vbus 1
USB-B
Receptacle
D- 2
D+ 3
GND 4
+3v
MU-4
2
4
5
6
7
1
8
9
12 11
10
13
14 INI
RXD TXD
RTSCTS
MOD
RSTRXM
RF
GND
VCC
DI
DO
RXL
3
TXL
2.2 Block Diagram

OG_MU4-USBIF_v10e 7 Circuit Design, Inc.
OPERATION GUIDE
◼2.3.1 General specifications
Parameter
Specification
Unit
Remark
Supply voltage
USB bus power
Consumption current
Transmitting: 59 / Receiving: 40
mA
USB bus power
Operating temperature
-20 to +65
ºC
The range varies with the temperature
conditions.
LED indicator
Tx, Rx, Power
Switch
Initialize
External dimensions
47 × 78 × 16 (W × D × H)
mm
Including the connector.
Not including the antenna.
Unit weight
26
g
◼2.3.2 USB interface specifications
■2.3.3 RS232C parameter specifications
Data speed
1,200/2,400/4,800/9,600/19,200/38,400/57,600 bps
Flow control
RTS/CTS hardware flow control
Other parameters
Data length 8 bits, no parity, 1 or 2 stop bits
Refer to the operation guide of the MU-4 mounted on the MU4-USBIF for the channel table. The frequency band is
shown on the label of the MU-4.
Item
Specification
Interface specification
USB Ver. 2.0 Full speed
Receptacle
USB-B type receptacle
Adapter
USB-B type plug
2.4 Channel Table
2.3 Main Specifications

OG_MU4-USBIF_v10e 8 Circuit Design, Inc.
OPERATION GUIDE
75
71 .5
14 .5
40
47
12 .05
1 .4
312 .4
2.5
10.9
180
4-Φ3.0
λ/4 lead an t enna
RF
GND VCC
RXD
CTS
INI
RXM
DO
RXL
TXD
RTS
MOD
RST
DI
TXL
MU-4-434
2.5 External Dimensions

OG_MU4-USBIF_v10e9 Circuit Design, Inc.
OPERATION GUIDE
MU-4
* When making your circuit board based on this circuit diagram, pay due attention to high frequency noise around the USB chip and from the interface.
1. Exercise caution in placement of the MU-4 and USB chip. In addition, there are cases where shielding is necessary around the chip.
2. Add a noise filter to the USB interface signal wire.
3. Ensure a sufficiently large ground pattern for the MU-4. In addition, provide shielding for the signal wire too.
2.6 Circuit Diagram

OG_MU4-USBIF_v10e10 Circuit Design, Inc.
OPERATION GUIDE
The MU4-USB (MU-4 + MU4-USBIF) uses a virtual COM port. Since it is basically used in the same way as the
MU-4, refer to “Chapter 4 How to Use the MU-4” in the MU-4 operation guide.
UI=0055
GI=02
EI=01
UI=0055
GI=02
EI=02
UI=0055
GI=02
EI=03
UI=0055
GI=02
EI=04
MU2-USB
MU4-USB
Note : UI=User ID GI=Group ID EI=Equipment ID DI=Destination ID
Same area
Group3(1:N system)
Group2(1:N system)
Group1(1:N system)
Chapter 3 How to Use the MU4-USB
3.1 System Configuration Example

OG_MU4-USBIF_v10e11 Circuit Design, Inc.
OPERATION GUIDE
◼3.2.1 Installing the USB Driver
The MU4-USB supports Windows plug and play. Connect the double shield USB cable (USB 2.0 High Speed) to the
unit, then connect the cable to the computer. The install USB driver window opens automatically. Follow the
instructions to install the driver. The MU4-USB driver file is located in the zip file [USB_Driver] folder.
The device may recognize as MU1-UIK or MU2-UIK. When installing the driver with Windows 8 or 10, please refer to
the application note on the website.
◼3.2.2 Uninstalling the USB Driver
To uninstall the driver, use the FTClean in the setup disk.
Input 13A7 as the vender ID and 1004 as the product ID to remove
the driver. The FTClean is located in the “FTClean”folder in the
“MU2_USB_Driver”folder.
Be sure to disconnect the MU4-USB from the
computer first. If you uninstall the driver with the
MU4-USB connected to the computer, the
Windows registry will not be deleted normally.
This may result in problems when you next
install the driver.
◼3.2.3 Checking that the USB Driver Works
To check that the USB driver works, use the Device Manager. Check that MU2-USB appears in the Properties.
Using the reset command @SR, the MU4-USB can be reset to the settings at the time the power was turned on. The
parameters fixed in the EEPROM remain unchanged.
Initialize the unit to the factory default settings if communication with the MU-4 mounted on the MU4-USB is not
possible or if you are uncertain of the internal settings.
How to initialize the MU-4
Turn on the power (connect the USB cable) while pressing the initialize button. Then turn the power off (remove the
USB cable) and on once again to reset the unit to the default settings. For details, refer to the default values for each
command in the MU-4 Operation Guide. The MU-4 can also be initialized with the initialize command @IZ.
Status after initializing
The values of the main parameters after initializing are as follows.
1. Link related parameters
User ID: UI = 0000, Group ID: GI = 00, Equipment ID: EI = 01, Destination ID: DI = 01, Channel = 0 channel
2. UART related parameters
Baud rate = 19,200 bps, parity = none, stop bit = 1
3. Parameters related to internal operation
Mode = command
3.2 The USB Driver
3.4 Initializing
Caution
3.3 Resetting

OG_MU4-USBIF_v10e12 Circuit Design, Inc.
OPERATION GUIDE
When embedding theMU4-USB (MU-4 + MU4-USBIF) in a user system, pay due attention to the design of the board
and case.
This board is connected to a PC provided with a USB port. Connect the unit to the PC with the dedicated USB cable
provided. Power for the product is supplied from the PC through the USB cable.
If you house the product in a case, determine the position of the ground and antenna through a variety of tests.
In addition, if you attach LEDs to the case, connect them with inch-pitch through holes with reference to the diagram
below.
If you use a USB cable other than the one provided, use a double shield cable (USB 2.0 High Speed). Otherwise,
radio waves may not be emitted due to high frequency noise from the USB.
When using USB, pay attention to the total current capacity of the other equipment since it can result in malfunctions.
When marketing products that use this product, provide information about the current in your operation guide.
◼4.1.1 Controlling the MU4-USB with a PC
MU-4
USB cable
User PC
λ/4 lead antenna *2
1
2
3
4
5
6
7
8
Power LED
Tx LED
Rx LED
RSSI
GND
GND
+3v
+3v
*１*１
*１*１
｝To the
processing circuit
100pF
100pF
MU4-USB
Inch pitch through holes only.
If necessary, mount an 8-pin
socket, and attach external LEDs
etc.
USB-B receptacle
100pF
Connecting external LEDs
・To prevent noise, attach a ceramic
capacitor of about 100 pF to the LED.
・Terminals 1, 3, and 5 there are 1kΩ
resistors in the MU4-USB.
*1: Solder the terminal lug etc. and connect it to the user case
ground. Determine the connection point with various tests.
*2: If the antenna is bent to fit inside, the communication
range falls and communication errors become frequent. Do
Not put the antenna inside a metal case.
4.1 Embedding the Product
Chapter 4 How to Design a User System

OG_MU4-USBIF_v10e13 Circuit Design, Inc.
OPERATION GUIDE
In systems where a non-directional antenna is required, it is important that the antennas of the transmitting station
and target stations stand vertically in order to exploit communication performance to the maximum. If the planes of
polarization of the radio waves do not match, receive sensitivity may drop significantly.
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 ways below, 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 MU4-USB 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
The antenna of the MU4-USB is a 1/4λ whip antenna. Whip antennas are antennas that substitute the ground as
one end of a dipole antenna. For this reason, the ground has a very important meaning. Although the main unit of
the MU2-USB has the function of a ground, in order to exploit its performance fully, connect it to the largest possible
ground pattern when mounting it on your circuit board.
In addition, in the case of two-way communication between fixed stations, inclining the whip antenna of the MU-4
forwards may increase its communication range. Carry out tests in the specific environment of use.
The MU4-USBIF is a test board that uses an USB interface to interface with external equipment. The MU4-USB is
made for test equipment, and is not a stand-alone product. The regulatory compliance assessment of the MU2-USB
in accordance with the RE Directive depends on the final product in which the MU4-USB is embedded. Regulatory
compliance assessment should be carried out on the responsibility of the manufacturer of the final product.
For details of the CE mark, refer to the MU-4 operation guide.
Point:
The MU-4 radio modem has passed the regulatory compliance assessment in accordance with RE Directive as a
stand-alone product, and has received the CE mark.
1. Always use double shield USB cable for connecting the MU4-USB.
2. Devise ways of isolating the MU-4 as far as possible from sources of noise, including noise from other
embedded equipment.
3. Arrange the MU4-USB so that it will not be covered by the operator’s hand or the like.
4. The MU4-USB 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.
The program that controls the MU4-USB (MU-4 + MU4-USBIF) is a program that accesses the COM port.
The method of developing a program is basically the same as for the MU-4, except for accessing a virtual COM port.
Refer to “Chapter 6 How to Develop a Program” in the MU-4 operation guide.
Chapter 5 How to Develop a Program
4.4 Cautions
4.3 Regulatory Compliance
4.2 The Antenna

OG_MU4-USBIF_v10e14 Circuit Design, Inc.
OPERATION GUIDE
When designing an original USB interface system similar to the MU4-USB using the MU-4, bear in mind the items
explained below.
Although the circuit diagram shown in this operation guide is a proper circuit, even when made in accordance with
the circuit diagram, it may not perform well due to high frequency noise from the surrounding circuitry.
Bear in mind the following when designing circuits.
1. Exercise caution in placement of the MU-4 and USB chip. In addition, there are cases where shielding is
necessary around the chip.
2. Add a noise filter to the USB interface signal wire.
3. Ensure a sufficiently large ground pattern for the MU-4. In addition, provide shielding for the signal wire too.
Use a double shield USB cable (USB 2.0 High Speed).
In order to assess the performance of your circuit board, issue the ‘@RA’ command to acquire the RSSI level of the
MU-4 and check the level. It is necessary to acquire and assess the level of all the channels. Set a standard lower
than the value acquired with the MU4-USB. Here it is convenient to use the air monitor of the MU-4 evaluation
program. In order to use the air monitor function, it is necessary to make a design in which the terminals of the MU-4
can be controlled from the outside.
If you design an original system with a USB interface, you will need a unique vendor ID. Vendor IDs are obtained
from USB-IF. For details, refer to the site below.
USB-IF website URL: http://www.usb.org/developers/vendor/
When you have a vendor ID, you can write it to the chip using an EEPROM programmer (MProg or the like) provided
by FTDI.
In addition, although you can use the FTDI USB driver, it is necessary to change several of the driver related files in
order to make the driver proprietary. Edit the Ftdibus.inf, Ftdiport.inf and Ftdiun2k.ini files in the driver folder to make
them apply to your company.
Chapter 6 When Designing an Original System
6.2 The USB Driver
6.1 The Circuits

OG_MU4-USBIF_v10e15 Circuit Design, Inc.
OPERATION GUIDE
The additions and changes are shown below underlined.
Example: Vendor ID = 1234, and product ID = 5678
◆Ftdibus.inf
[FtdiHw]
%USB¥VID_0403&PID_6001.DeviceDesc%=FtdiBus.NT,USB¥VID_0403&PID_6001
%USB¥VID_0403&PID_6010&MI_00.DeviceDesc%=FtdiBus.NT,USB¥VID_0403&PID_6010&MI_00
%USB¥VID_0403&PID_6010&MI_01.DeviceDesc%=FtdiBus.NT,USB¥VID_0403&PID_6010&MI_01
Add %USB¥VID_1234&PID_5678.DeviceDesc%=FtdiBus,USB¥VID_1234&PID_5678
[FtdiHw.NTamd64]
%USB¥VID_0403&PID_6001.DeviceDesc%=FtdiBus.NTamd64,USB¥VID_0403&PID_6001
%USB¥VID_0403&PID_6010&MI_00.DeviceDesc%=FtdiBus.NTamd64,USB¥VID_0403&PID_6010&MI_00
%USB¥VID_0403&PID_6010&MI_01.DeviceDesc%=FtdiBus.NTamd64,USB¥VID_0403&PID_6010&MI_01
Add %USB¥VID_1234&PID_5678.DeviceDesc%=FtdiBus.NTamd64,USB¥VID_1234&PID_5678
[Strings]
Ftdi="FTDI"
DESC="CDM Driver Package"
DriversDisk="FTDI USB Drivers Disk"
USB¥VID_0403&PID_6001.DeviceDesc="USB Serial Converter"
USB¥VID_0403&PID_6010&MI_00.DeviceDesc="USB Serial Converter A"
USB¥VID_0403&PID_6010&MI_01.DeviceDesc="USB Serial Converter B"
Add USB¥VID_1234&PID_5678.DeviceDesc="My New USB Device"
◆Ftdiport.inf
[FtdiHw]
%VID_0403&PID_6001.DeviceDesc%=FtdiPort232.NT,FTDIBUS¥COMPORT&VID_0403&PID_6001
%VID_0403&PID_6010.DeviceDesc%=FtdiPort2232.NT,FTDIBUS¥COMPORT&VID_0403&PID_6010
Add %VID_1234&PID_5678.DeviceDesc%=FtdiPort232,FTDIBUS¥COMPORT&VID_1234&PID_5678
[FtdiHw.NTamd64]
%VID_0403&PID_6001.DeviceDesc%=FtdiPort232.NTamd64,FTDIBUS¥COMPORT&VID_0403&PID_6001
%VID_0403&PID_6010.DeviceDesc%=FtdiPort2232.NTamd64,FTDIBUS¥COMPORT&VID_0403&PID_6010
Add %VID_1234&PID_5678.DeviceDesc%=FtdiPort232.NTamd64,FTDIBUS¥COMPORT&VID_1234&PID_5678
[Strings]
FTDI="FTDI"
DESC="CDM Driver Package"
DriversDisk="FTDI USB Drivers Disk"
PortsClassName = "Ports (COM & LPT)"
VID_0403&PID_6001.DeviceDesc="USB Serial Port"
VID_0403&PID_6010.DeviceDesc="USB Serial Port"
Add VID_1234&PID_5678.DeviceDesc="My New USB Device"
For details, refer to the information concerning changes to the FTDI driver related files.
Note: The USB driver for the MU4-USB has the Circuit Design vendor ID, and you are not authorized to use it.
The USB/UART conversion chip uses the FTDI FT8U232BM, and by downloading the direct driver from the FTDI
website, you can control the USB interface directly without using the COM port.
However, we do not provide support for direct control. This should be carried out on the responsibility of the
developer.
6.3 Directly Controlling the USB Chip

OG_MU4-USBIF_v10e16 Circuit Design, Inc.
OPERATION GUIDE
Important notice
•Customers are advised to consult with Circuit Design sales representatives before ordering.
Circuit Design believes the provided information is accurate and reliable. However, Circuit Design reserves the right
to make changes to this product without notice.
•Circuit Design products are neither designed nor intended for use in life support applications where malfunction
can reasonably be expected to result in significant personal injury to the user. Any use of Circuit Design products
in such safety-critical applications is understood to be fully at the risk of the customer and the customer must fully
indemnify Circuit Design, Inc for any damages resulting from any improper use.
•As the radio module communicates using electronic radio waves, there are cases where transmission will be
temporarily cut off due to the surrounding environment and method of usage. The manufacturer is exempt from all
responsibility relating to resulting harm to personnel or equipment and other secondary damage.
•The manufacturer is exempt from all responsibility relating to secondary damage resulting from the operation,
performance and reliability of equipment connected to the radio module.
Copyright
•All rights in this operation guide are owned by Circuit Design, Inc. No part of this document may be copied or
distributed in part or in whole without the prior written consent of Circuit Design, Inc.
Cautions
•Do not use the equipment within the vicinity of devices that may malfunction as a result of electronic radio waves
from the radio module.
•Communication performance will be affected by the surrounding environment, so communication tests should be
carried out before actual use.
•Ensure that the power supply for the radio module is within the specified rating. Short circuits and reverse
connections may result in overheating and damage and must be avoided at all costs.
•Ensure that the power supply has been switched off before attempting any wiring work.
•The case is connected to the GND terminal of the internal circuit, so do not make contact between the '+' side of
the power supply terminal and the case.
•When batteries are used as the power source, avoid short circuits, recharging, dismantling, and pressure. Failure
to observe this caution may result in the outbreak of fire, overheating and damage to the equipment. Remove the
batteries when the equipment is not to be used for a long period of time. Failure to observe this caution may result
in battery leaks and damage to the equipment.
•Do not use this equipment in vehicles with the windows closed, in locations where it is subject to direct sunlight, or
in locations with extremely high humidity.
•The radio module is neither waterproof nor splash proof. Ensure that it is not splashed with soot or water. Do not
use the equipment if water or other foreign matter has entered the case.
•Do not drop the radio module or otherwise subject it to strong shocks.
•Do not subject the equipment to condensation (including moving it from cold locations to locations with a
significant increase in temperature.)
•Do not use the equipment in locations where it is likely to be affected by acid, alkalis, organic agents or corrosive
gas.
•Do not bend or break the antenna. Metallic objects placed in the vicinity of the antenna will have a great effect on
communication performance. As far as possible, ensure that the equipment is placed well away from metallic
objects.
•The GND for the radio module will also affect communication performance. If possible, ensure that the case GND
and the circuit GND are connected to a large GND pattern.
Warnings
•Do not take a part or modify the equipment.
•Do not remove the product label (the label attached to the upper surface of the module.) Using a module from
which the label has been removed is prohibited.
Copyright 2020, Circuit Design, Inc.

OG_MU4-USBIF_v10e17 Circuit Design, Inc.
OPERATION GUIDE
REVISION HISTORY
Version
Date
Description
Remark
1.0
Sep. 2020
MU4-USBIF The first issue