OG_MU-4-434_v10e Circuit Design, Inc.
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OPERATION GUIDE
6.8.2 When developing a new system
The binary mode of the MU-4 can be used in accordance with the following methods, however when it is used in this
mode, it must meet the
“Conditions for use of the binary mode”
, explained later.
Set the MODE terminal to be controlled by the CPU.
1. Using the binary mode while switching between the binary mode and command mode
With applications that must change channels and the destination of transmissions, switch between the command
mode and binary mode, using the CPU to control the MODE terminal.
2. Using only the binary mode directly after turning on the power
If you want to use the MU-4 in the binary mode directly after turning on the power of the system, without changing
channels or the destination of transmissions, issue the command “@MD BI /W” to set the MU-4 mode register and
to fix the mode in the EEPROM. This setting is made only once at the beginning when first using the system. In
addition, when turning on the power, set the MODE terminal to L.
Use the command ‘/W’ option to fix the channel, User ID, Destination ID and so on in the EEPROM.
3. Connection example
These are examples of connections in which hardware flow control is used and not used.
Normally with the MU-4, in order to prevent buffer overflow of the data buffer, hardware flow control is fixed as the
flow control for serial communication. This also applies to the binary mode. However, if the data to send at one
time is less than 255 bytes, data can be sent without performing flow control.
In addition, since the various setting commands of the MU-4 are only a few bytes, there is no particular need for a
flow control line.
When using hardware flow control
Set the UART of the control CPU to be controlled by hardware flow control.
When not using hardware flow control
1. Set the CTS terminal to L level, and open the RTS terminal.
2. Set the UART of the control CPU to no flow control.
Antenna
RXD
TXD
CTS(Port)
RTS(Port)
Port
MU-
4
TXD 1
RXD 2
RTS 3
CTS 4
MOD 5
INI 6
RST 7
RXM 8
RF
14 GND
13 VCC
12 RXL
11 TXL
10 DO
9 DI
User CPU
With UART
Antenna
RXD
TXD
MU-4
TXD 1
RXD 2
RTS 3
CTS 4
MOD 5
INI 6
RST 7
RXM 8
RF
14 GND
13 VCC
12 RXL
11 TXL
10 DO
9 DI
User CPU
With UART
