Product Info

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design
3-22
/ 105
Main UART Interface
Pin Name
Pin No.
I/O
Description
DC Characteristics
Comment
RI
62
DO
Ring indicator
V
OL
max=0.45V
V
OH
min=1.35V
1.8V power domain.
If unused, keep it
open.
DCD
63
DO
Data carrier
detection
V
OL
max=0.45V
V
OH
min=1.35V
1.8V power domain.
If unused, keep it
open.
CTS
64
DO
Clear to send
V
OL
max=0.45V
V
OH
min=1.35V
1.8V power domain.
If unused, keep it
open.
RTS
65
DI
Request to send
V
IL
min=-0.3V
V
IL
max=0.6V
V
IH
min=1.2V
V
IH
max=2.0V
1.8V power domain.
If unused, keep it
open.
DTR
66
DI
Data terminal ready,
sleep mode control
V
IL
min=-0.3V
V
IL
max=0.6V
V
IH
min=1.2V
V
IH
max=2.0V
1.8V power domain.
Pulled up by default.
Low level wakes up
the module.
If unused, keep it
open.
TXD
67
DO
Transmit data
V
OL
max=0.45V
V
OH
min=1.35V
1.8V power domain.
If unused, keep it
open.
RXD
68
DI
Receive data
V
IL
min=-0.3V
V
IL
max=0.6V
V
IH
min=1.2V
V
IH
max=2.0V
1.8V power domain.
If unused, keep it
open.
Debug UART Interface
Pin Name
Pin No.
I/O
Description
DC Characteristics
Comment
DBG_TXD
12
DO
Transmit data
V
OL
max=0.45V
V
OH
min=1.35V
1.8V power domain.
If unused, keep it
open.
DBG_RXD
11
DI
Receive data
V
IL
min=-0.3V
V
IL
max=0.6V
V
IH
min=1.2V
V
IH
max=2.0V
1.8V power domain.
If unused, keep it
open.
ADC Interface
Pin Name
Pin No.
I/O
Description
DC Characteristics
Comment