Product Info

LTE Standard Module Series
EC25 Mini PCIe Hardware Design
EC25_Mini_PCIe_Hardware_Design
31
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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.
It is prohibited to be pulled up high