GSM/GPRS Module
M85 Hardware Design
M85_Hardware_Design Confidential / Released 52 / 92
In Figure 33, the pin SIM_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 or not. When the tray is inserted in the socket,
SIM_PRESENCE is at low level. Regardless of whether the SIM card is in the tray or not, the change of
SIM_PRESENCE level from high to low level inspires the module to reinitialize SIM card. In default
configuration, SIM card detection function is disabled. You can use ―AT+QSIMDET=1,0 ‖ to switch on and
―AT+QSIMDET=0,0 ‖ to switch off the SIM card detection function. For details about this AT command,
please refer to the
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 READY
When the tray with SIM card is inserted into SIM socket again and the module finishes
re-initialization SIM card, the following URC will be presented.
Call Ready
The following figure is the reference design for SIM1 interface with 8-pin SIM card holder.
VDD_EXT
Module
SIM1_VDD
SIM_GND
SIM1_RST
SIM1_CLK
SIM1_DATA
SIM1_PRESENCE
22R
22R
22R
10K
100nF
SIM_Holder
GND
GND
ESDA6V8V6
33pF
33pF 33pF33pF
VCC
RST
CLK
IO
VPP
GND
GND
Figure 33: Reference Circuit for SIM1 Interface with 8-pin SIM Card Holder
53
SIM1_RST
SIM card reset.
74
SIM2_RST
57
SIM1_PRESENCE
SIM1 card detection.
52
SIM_GND
SIM card ground.
Quectel
Confidential