User's Manual

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 22 / 94
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.
Pull-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
ADC0 45 AI
General purpose
analog to digital
converter
Voltage range:
0.3V to VBAT_BB
If unused, keep it open.
ADC1 44 AI
General purpose
analog to digital
converter
Voltage range:
0.3V to VBAT_BB
If unused, keep it open.