24
7.1.2. Software flow control
This flow control function uses three wires, RXD, TXD and GND in RS232. When DCE is
receiving data from DTE, to prevent received data from exceeding the buffer1 capacity
in DCE, the DCE sends command of transmission halt request which is XOFF code to
the DTE. When the buffer1 have room to receive data again, the DCE sends command of
transmission request which is XON code to the DTE.
DTE
Slave MCU
Modem IC
RF
TXD
Modem CTRL
Modem DATA
Modulated
Data
Received
Data
RXD
GND
<RS232>
Control Line
<Modem Option Board>
Master MCU
Control Line
<SD160 Main Digital Board>
<SD160 RF Board>
Buffer 1
Buffer 2
Figure 7.1. Data and Control signal flow in Software flow control
Pin connection
Configuration of pin connecting for software flow control is the following.
1
5
6
10
11
15
1
5
96
4 GND
10 SERIAL_IN
11 SERIAL_OUT
RXD 2
TXD 3
GND 5
6 DSR
4 DTR
8 CTS
9 RTS
Figure 7.2. Pin connection for Software flow control
7.1.3. Hardware flow control
This flow control function is performed by using the control lines RTS(Request To
Send), CTS(Cleat To Send), TXD, RXD and GND in RS232. When the DTE has data to
