SIM900D Hardware Design
3.11 SIM Card Interface
3.11.1 SIM Card Application
User can use AT Command to get information in SIM card. For more information, please refer to
related
document [1]
.
The SIM interface complies to the GSM Phase 1 specification and the new GSM Phase 2+ specification for FAST
64 kbps SIM (intended for use with a SIM application Tool-kit). Both 1.8V and 3.0V SIM Cards are supported.
The SIM interface is powered from an internal regulator in the module. All pins are described in the following
table.
Table16: Pin definition of the SIM interface
Pin Name
Pin Number
Function
SIM_VDD
9
SIM Card Power output automatic output on SIM mode
，
one is
3.0V±10%, another is 1.8V±10%. Current is about 10mA.
SIM_DATA
6
SIM Card data I/O
SIM_CLK
7
SIM Card Clock
SIM_RST
8
SIM Card Reset
Following figure is the reference circuit about SIM interface. SIMCom recommends an Electro-Static discharge
device ST (
) ESDA6V1W5 or ON SEMI (
) SMF05C for “ESD ANTI”. The 22
Ω
resistors showed in the following figure should be added in series on the IO line between the module and the SIM
card for protecting the SIM I/O port. The pull-up resistor (about 15K
Ω
) on the SIM_DATA line is already added
in the module. Note that the SIM peripheral circuit should be close to the SIM card socket.
The KBR0 pin is used for detecting the SIM card insert or removal. User can use the AT command “AT+CSDT”
to switching on or off SIM card detection function. For details of this AT command, please refer to
related
document [1]
。
User can select the 8-pin SIM card holder to implement SIM card detection function. The reference
circuit of the 8-pin SIM card holder is illustrated as following figure.
SIM900D_Hardware Design_V1.04
2010.10.09
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