Quectel EC21-AU User Manual

LTE Standard Module Series
EC21_Series_Hardware_Design
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The pins of PCM interface are used for audio design on EC21 series module and Bluetooth function on FC20
series/FC21 modules.
Pin Name Pin No. I/O Description
DC
Characteristics
Comment
DBG_TXD 12 DO
Debug UART
transmit
V
OL
max = 0.45 V
V
OH
min = 1.35 V
1.8 V power domain.
If unused, keep them
open.
DBG_RXD 11 DI
Debug UART
receive
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
ADC Interface
Pin Name Pin No. I/O Description
DC
Characteristics
Comment
ADC0 45 AI
General-purpose
ADC interface
Voltage range:
0.3 V to VBAT_BB
If unused, keep them
open.
ADC1 44 AI
General-purpose
ADC interface
Voltage range:
0.3 V to VBAT_BB
PCM Interface
6
Pin Name Pin No. I/O Description
DC
Characteristics
Comment
PCM_IN 24 DI PCM data input
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
1.8 V power domain.
If unused, keep them
open.
PCM_OUT 25 DO PCM data output
V
OL
max = 0.45 V
V
OH
min = 1.35 V
PCM_SYNC 26 DIO
PCM data frame
sync
V
OL
max = 0.45 V
V
OH
min = 1.35 V
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
1.8 V power domain.
Serve as output signal
in master mode.
Serve as input signal
in slave mode.
If unused, keep them
open.
PCM_CLK 27 DIO PCM clock
I2C Interface
Pin Name Pin No. I/O Description
DC
Characteristics
Comment
I2C_SCL 41 OD
I2C serial clock (for
external codec)
An external 1.8 V pull-
up resistor is required.
If unused, keep them
open.
I2C_SDA 42 OD
I2C serial data (for
external codec)
SD Card Interface

Quectel EC21-AU Specifications

General

Brand	Quectel
Model	EC21-AU
Category	Control Unit
Language	English