GSM/GPRS Module
M85 Hardware Design
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3.9. Dual-SIM Card Interface
The module contains two smart interfaces to allow module access the two SIM cards. Only one SIM card
can work at a time. These two SIM interfaces share the same ground and only SIM1 interface has card
inserted detection.
In dual SIM card mode, configure ―AT + QDSIM = 0‖ to use the SIM1 interface and configure ―AT +
QDSIM= 1‖ to use SIM2 interface. M85 is set to SIM1 Mode by default. For more details, please refer to
the
document [1]
.
3.9.1. SIM Card Application
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 13: Pin Definition of the SIM Interface
AOUT2
Output
Single-ended
Load resistance
16
32
Load Resistance
Reference level
0
2.4
Vpp
AOUT3
Output
Differential
Load resistance
8
Load Resistance
Reference level
0
2×VBAT Vpp
Pin NO.
Name
Description
56
SIM1_VDD
Supply power for SIM card. Automatic detection of SIM card voltage.
3.0V±10% and 1.8V±10%. Maximum supply current is around
10mA.
71
SIM2_VDD
55
SIM1_CLK
SIM card clock.
72
SIM2_CLK
54
SIM1_DATA
SIM card data I/O.
73
SIM2_DATA
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