GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 51 / 88
The following figure is the reference design for SIM interface, and here an 8-pin SIM card holder is used.
The pin SIM1_PRESENCE is used to detect whether the tray of the Molex SIM socket, which is used for
holding SIM card, is present in the card socket. When the tray is inserted in the socket, SIM1_PRESENCE
is at low level. Regardless of the SIM card is in the tray or not, the change of SIM1_PRESENCE level from
high to low level prompts the module to reinitialize SIM card. In default configuration, SIM card detection
function is disabled. Your application can use
AT+QSIMDET=1,0
and
AT+QSIMDET=0,0
to switch on and
off the SIM card detection function. For details of this AT command, please refer to
document [1]
. When
AT+QSIMDET=1,0
is set and the tray with SIM card is removed from SIM socket, the following URC will be
presented:
+CPIN: NOT INSERTED
When the tray with SIM card is inserted into SIM socket again and the module finishes reinitializing SIM
card, the following URC will be presented:
+CPIN: READY
Call Ready
VDD_EXT
Module
SIM1_VDD
SIM_GND
SIM1_RST
SIM1_CLK
SIM1_DATA
SIM1_PRESENCE
22R
22R
22R
10K
100nF
SIM_Holder
GND
GND
TVS
33pF
33pF 33pF33pF
VCC
RST
CLK
IO
VPP
GND
GND
Figure 32: Reference Circuit for SIM1 Interface with 8-pin SIM Card Holder
SIM1_PRESENCE
57
SIM1 card detection
SIM_GND
52
SIM card ground
