SIM908 EVB kit User Guide
4.1 GSM serial ports
Figure 13: GSM serial ports
Pin
Signal
I/O
Description
1 TXD
O
Transmit
data
2 RXD
I
Receive
data
3
DCD
O
Data carrier detection
4 RI
O
Ring
Indicator
5 CTS
O
Clear
to
Send
6 GND
GND
7 DTR
I
Data
Terminal
Ready
8 DEBUG_RX
I
Receive
data
9 RTS
I
Request
to
Send
10 DEBUG_TX O
Transmit
data
SIM908_EVB kit_ User Guide _V1.00
2011.8.15
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