Product Info

LTE Standard Module Series
EC21_Series_Mini_PCIe_Hardware_Design
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3.8. UART Interface
EC21 series Mini PCIe module provides one main UART interface. The main UART interface supports
9600 bps, 19200 bps, 38400 bps, 57600 bps, 115200 bps and 230400 bps baud rates, and the default is
115200 bps.
The main UART interface supports RTS and CTS hardware flow control, and be used for AT command
communication and data transmission.
The following table shows the pin definition of the main UART interface.
Table 10: Pin Definition of Main UART Interface
The signal level of main UART interface is 3.3 V. When connecting to the peripheral MCU/RAM,
customers need to pay attention to the signal direction. The reference circuit is shown as below:
Figure 7: Reference Circuit of Power Supply
Pin Name Pin No. I/O Description Power Domain
UART_RX 11 DI UART receive 3.3 V
UART_TX 13 DO UART transmit 3.3 V
UART_CTS 23 DI DCE clear to send signal from DTE 3.3 V
UART_RTS 25 DO DCE request to send signal from DTE 3.3 V