Users Manual

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 21 / 82
PIN Name PIN No. I/O Description DC Characteristics Comment
NETLIGHT 16 DO Network status indication
V
OH
min=
0.85×VDD_EXT
V
OL
max=
0.15×VDD_EXT
If unused,
keep this pin
open.
UART Port
PIN Name PIN No. I/O Description DC Characteristics Comment
TXD 17 DO Transmit data
V
IL
min=0V
V
IL
max=
0.25×VDD_EXT
V
IH
min=
0.75×VDD_EXT
V
IH
max=
VDD_EXT+0.2
V
OH
min=
0.85×VDD_EXT
V
OL
max=
0.15×VDD_EXT
If only use
TXD, RXD and
GND to
communicate,
recommended
to keep other
pins open.
RXD 18 DI Receive data
DTR 19 DI Data terminal ready
RI 20 DO Ring indication
DCD 21 DO Data carrier detection
CTS 22 DO Clear to send
RTS 23 DI Request to send
Debug Port
PIN Name PIN No. I/O Description DC Characteristics Comment
DBG_
TXD
39 DO Transmit data
Same as above
If unused,
keep these
pins open.
DBG_
RXD
38 DI Receive data
Auxiliary Port
PIN Name PIN No. I/O Description DC Characteristics Comment
TXD_
AUX
29 DO Transmit data
Same as above
If unused,
keep these
pins open.
RXD_
AUX
28 DI Receive data
SIM Interface
PIN Name PIN No. I/O Description DC Characteristics Comment
SIM_ VDD 14 PO Power supply for SIM card
The voltage can be
selected by software
automatically. Either
1.8V or 3.0V.
All signals of
SIM interface
should be
protected
against ESD
with a TVS
SIM_ CLK 13 DO SIM clock
V
OL
max=
0.15×SIM_VDD