Quectel EC25 Mini PCIe - COEX UART Interface

LTE Standard Module Series
EC25 Mini PCIe Hardware Design
EC25_Mini_PCIe_Hardware_Design 28 / 79
The following table shows the pin definition of the main UART interface.
Table 9: Pin Definition of Main UART Interface
The signal level of main UART interface is 3.3V. When connecting to the peripheral MCU/RAM,
customers need to pay attention to the signal direction. The reference circuit is as follows:
MCU/ARM
TXD
RXD
UART_RXD
UART_TXD
UART_RTS
UART_CTS
RTS
CTS
GND
Module
GND
Voltage level: 3.3V
Voltage level: 3.3V
Figure 7: Reference Circuit of Power Supply
3.8.2. COEX UART Interface*
The following table shows the pin definition of the COEX UART interface.
Table 10: Pin Definition of COEX UART Interface
Pin Name
Pin No.
I/O
Power Domain
Description
UART_RX
11
DI
3.3V
UART receive data
UART_TX
13
DO
3.3V
UART transmit data
UART_CTS
23
DI
3.3V
UART clear to send
UART_RTS
25
DO
3.3V
UART request to send
Pin No.
Pin Name
I/O
Power Domain
Description
3
COEX_UART_RX
DI
1.8V
LTE/WLAN&BT coexistence receive
signal.