M12 Hardware Design
M12_Hardware_Design_V3.3
- 21 -
Main Serial port
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
DTR
59
I
Data terminal
ready
VILmin=-0.3V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
0.3
VOLmax=
0.15×VDD_EXT
VOHmin=
0.85×VDD_EXT
If only use TXD,
RXD and GND to
communicate,
recommended
connecting RTS to
GND via 0R
resistor and
keeping other pins
open.
RXD
61
I
Receive data
TXD
60
O
Transmit data
RTS
58
I
Request to send
CTS
57
O
Clear to send
RI
55
O
Ring indicator
DCD
56
O
Data carrier
detection
Debug port
DBG_TXD
10
O
Serial interface for
debugging only
Same as above
If unused, keep
these pins open.
DBG_RXD
9
I
UART3
TXD3
62
O
Transmit data
Same as above
If unused, keep
these pins open.
RXD3
63
I
Receive data
SD card interface
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
SD_DATA
1
I/O
SD serial data
VILmin=-0.3V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
0.3
VOLmax=
0.15×VDD_EXT
VOHmin=
0.85×VDD_EXT
If unused, keep
these pins open.
If used,
SD_DATA is
connected to SD
card DATA0 pin.
SD_CLK
2
O
SD serial clock
VOLmax=
0.15×VDD_EXT
VOHmax=
0.85×VDD_EXT
SD_CMD
3
O
SD command
SIM interface
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
Quectel
Confidential