User's Manual

L811-EA Module Hardware User Manual Page
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The definition of UART1 signals as shown in the following tables:
Pin#
Pin Name
I/O
Description
L14
UART1_CTS
I
Clear to send
K14
UART1_RTS
O
Request to send
A9
UART1_TXD
O
Data Transmit
A10
UART1_RXD
I
Date Receive
5.6.2 UART Interface Application
The signal direction when connecting the UART1 of L811-EA module (DCE) and MCU (DTE) as shown in
the following tables:
MCU (DTE) application
Signal direction
L811-EA module (DCE)
RXD
UART1_TXD
TXD
UART1_RXD
Note:
The voltage level of UART interface is 1.8V. When connecting to 2.8V or 3.3V I/O, it is necessary to
convert the voltage level. In circuit design, it is recommended to use a SN74LVC2G07 to convert the
voltage level from 1.8V to 3.3V. For connecting to a PC, first convert 1.8V to 3.3V, then use a
SPIEX3232EEA to convert it to RS-232 level. The direction of the signals should be properly handled.
5.7 USIM Interface
The L811-EA module supports USIM and high speed SIM cards (The 8-wire USIM is not supported yet).
5.7.1 USIM Pins
Pin#
Pin Name
I/O
Function Description
D15
VSIM1
O
USIM power, 1.8V/2.8V
E15
SIM1_RST
O
USIM reset
F15
SIM1_CLK
O
USIM clock
G15
SIM1_DATA
I/O
USIM data
H15
SIM1_CD
I
USIM card detection signal, pulled up with a 390k
resistor by default.
High when SIM card is inserted.
Low when SIM card is not inserted.