User's Manual

L811-EA Module Hardware User Manual Page
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(SW2), and Pin7 (SW1) is pulled up with a 4.7K resistor. When the SIM card is not inserted, SW2 and
SW1 are opened, and SW2 is low. When the SIM card is inserted, SW2 and SW1 are shorted, and
SIM1_CD signal will be pulled high.
5.7.4.2 Software Setup
“+MSMPD” command is used for the SIM card detection function:

If set AT+MSMPD=0, the SIM card detection function is disabled, and the module will not detect the
SIM1_CD signal.

If set AT+MSMPD=1, the SIM card detection function is enabled, and the module will detect the
insertion of the SIM card via SIM1_CD Pin.
 If SIM1_CD is high, which indicates the insertion of a SIM card, and the module will automatically
register to the network.

If SIM1_CD is low or disconnected, which indicates the SIM card is not inserted, and the module will
not register to the network.
Note:
The default value of +MSMPD is “1”. The SIM_CD signal is used for SIM card detection. The module
detects the presence of the SIM card via the SIM1_CD signal during the first booting. After the module
boots up, it detects the SIM card by the level change of the SIM1_CD signal. In other words, if SIM1_CD
is at low level, the module cannot access the SIM card.
5.8 Digital Audio
The L811-EA module supports I2S interface for digital audio. The I2S port supports normal I2S mode and
PCM mode for data transfer. I2S interface is at 1.8V voltage level.
I2S signal description as shown in the following tables:
Pin#
Pin Name
I/O
Description
N12
I2S2_CLK
O
Bit clock, 1.8V signal
N9
I2S2_WA0
O
Left and right channel clock (LRCK), 1.8V signal
N10
I2S2_TX
O
Serial data output, 1.8V signal
N11
I2S2_RX
I
Serial data input, 1.8V signal
5.8.1 I2S Interface
L811-EA
Signal Direction
Audio CODEC I2S Port