User's Manual

GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 50 / 88
3.9. SIM Card Interfaces
The module contains two SIM interfaces to allow module access the two SIM cards. Only one SIM card
can work at a time. Both of two SIM interfaces share the ground and only first SIM interface have card
insert detection.
In dual SIM card mode, configure AT+QDSIM=0 to use the SIM1 interface and configure AT+QDSIM=1 to
use SIM2 interface. For more details, please refer to the document [1].
The SIM interface supports the functionality of the GSM Phase 1 specification and also supports the
functionality of the new GSM Phase 2+ specification for FAST 64 kbps SIM card, which is intended for
use with a SIM application Tool-kit.
The SIM interface is powered by an internal regulator in the module. Both 1.8V and 3.0V SIM Cards are
supported.
Table 12: Pin Definition of the SIM Interface
AOUT2
Output
Single-ended
Load resistance
32
Ohm
Ref level
0
2.4
Vpp
AOUT3
Output
Differential
Load resistance
8
Ohm
Ref level
0
2×VBAT
Vpp
Pin Name
Pin No.
Description
SIM1_VDD
56
Supply power for SIM card. Automatic detection of SIM
card voltage. 3.0V±10% and 1.8V±10%. Maximum
supply current is around 10mA.
SIM2_VDD
71
SIM1_CLK
55
SIM card clock
SIM2_CLK
72
SIM1_DATA
54
SIM card data I/O
SIM2_DATA
73
SIM1_RST
53
SIM card reset
SIM2_RST
74