Option board pin-out chart
FFSK Modem Option board
Connector
No.
Pin
No.
Function
Description
Input/
Output
Connector 1
1
VCC
6V to 12V Power Input
I/P
2
GND
Ground
3
PTT
Signal from the digital board to transmit data key the SD-
170 transmitter
I/P
4
TXD_EN
It ensures that the radio has stabilized in transmission
before the data is processed for modulation.
I/P
5
TX_END
To finish transmission, it indicates memory buffer of Master
MCU of digital board is empty.
O/P
6
MUTE
(Busy)
Logic level input from digital board to indicate whether a
carrier is present or not
I/P
7
MODEM_EN
Modem Enable input
I/P
8
POWER_SAVE
Power save input for modem board.
I/P
9
CMD_EN
It indicates that command for Modem programming is
effective.
I/P
10
CMD_IN/OUT
Data Input and Output for Modem programming.
I/P,
O/P
11
CMD_CLK
Clock Input for Modem programming.
I/P
12
MODEM_SEL
It Indicates modem type to Master MCU for programming.
O/P
13
RX_IN
The FFSK/MSK signal input for the receiver of modem IC.
I/P
14
TX_OUT
The FFSK/MSK signal output when the transmitter is
enabled.
O/P
Connector 2
1
Serial_IN
The Serial data to be transmitted is input to this pin.
I/P
2
Serial_OUT
The recovered asynchronous serial data output from the
receiver.
O/P
3
Busy
To eliminate data loss according to buffer overrun of slave
MCU
‟
s memory, it indicates buffer status.
O/P
4
Carrier_Detect
Handshake signal for RTS control mode. It indicates
whether Slave MCU of modem has decoded data or not.
O/P
5
PTT_IN
Handshake signal for RTS control mode. It requests data
transmission to Slave MCU of modem.
I/P
6
PROGRAM
It
‟
s reserved input for firmware upgrade.
I/P
20