LTE Standard Module Series
EG25-GL_Hardware_Design 51 / 96
The following figure shows a reference design of WLAN and Bluetooth application interfaces with Quectel
FC20 series or FC21 module.
5
Pins (Pin 24
–27) of PCM interface can be used not only for audio function on EG25-GL module, but also for Bluetooth
function
*
on FC20 series or FC21 module.
WIRELESS
signal to the module
up the module.
1.8 V power domain.
Active low.
If unused, keep it open.
COEX_RXD
137
DI
LTE & WLAN/ Bluetooth
coexistence receive
1.8 V power domain.
Cannot be pulled up before startup.
If unused, keep it open.
COEX_TXD
138
DO
LTE & WLAN/
Bluetooth coexistence
transmit
Bluetooth Application Interfaces
BT_RTS
*
37
DI
DTE request to send signal to
DCE
Connect to DTE's RTS.
1.8 V power domain.
If unused, keep it open.
BT_TXD
*
38
DO
Bluetooth UART transmit
1.8 V power domain.
If unused, keep it open.
BT_RXD
*
39
DI
Bluetooth UART receive
BT_CTS
*
40
DO
DTE clear to send signal from
DCE
Connect to DTE
’s CTS.
1.8 V power domain.
Cannot be pulled up before startup.
If unused, keep it open.
BT_EN
*
139
DO
Bluetooth enable control
1.8 V power domain.
If unused, keep it open.
PCM_DIN
5
24
DI
PCM data input
1.8 V power domain.
If unused, keep it open.
DO
PCM data output
DIO
PCM data frame sync
1.8 V power domain.
In master mode, it is an output signal.
In slave mode, it is an input signal.
If unused, keep it open.
27
DIO
PCM clock
