9
Cellular and end-to-end data plane connectivity setup
The Discovery board comes with a pre
‑
programmed application that demonstrates an out-of-the-box end
‑
to
‑
end
with low
‑
power connectivity over LTE Cat M or NB-IoT technology.
For flexibility, the Discovery board supports the dual SIM feature which allows switching between a plastic SIM
card inserted in a SIM socket or the embedded SIM (eSIM) inside the LBAD0ZZ1SE module.
The SIM selection policy is controlled by the modem firmware running on LBAD0XX1SC and stored in its
configuration files which can be modified via AT command. By default, the SIM selection policy is controlled by the
software package provided by STMicroelectronics dedicated for this board and the user does not need to send
explicitly an AT command.
Figure 12.
LBAD0ZZ1SE structure diagram
ST4SIM-200M supports also an embedded Secure Element (eSE). The eSE can be used to store application
(cloud) credentials (device certificates and keys). The eSE service can be accessed via ISO, modem firmware, or
from the STM32 application through the SPI interface.
9.1
SIM card socket
CN2 is a micro-SIM (3FF) card slot that supports only the class
‑
C SIM card (1.8V). The modem firmware detects
the presence of the SIM card and monitors in runtime SIM removal or insertion. By default, when a SIM card is
inserted, it is used for cellular connectivity, otherwise, eSIM provides connectivity to cellular networks.
Runtime detection of SIM insertion/removal may not be supported by the default pre-programmed application, but
a newer version of such application can be downloaded from
. If the runtime detection function is not
supported, the user does need to force a reboot by pressing the black “reset button”, after a SIM card is inserted
or removed to force the application to select the SIM slot and use the SIM for the cellular connectivity.
Note:
The modem firmware is certified by GCF and PTCRB. The user may use a plastic SIM card from any mobile
operator but the modem firmware may not have passed the certification from that specific operator. Therefore,
the usage of a plastic SIM card is only at the user's responsibility and it may need an additional procedure to
activate the SIM card. The user may contact Murata to get information about the list of operators on which the
modem firmware is certified.
When a SIM card is used, the cellular middleware can automatically set the APN to be used during registration
to the network. thanks to a pre-defined table IMSI (MCC/MNC) to APN. However, if the IMSI is unknown, the
end-customer may need to define explicitly the APN as defined in the user manual
X-CUBE-CELLULAR cellular
connectivity Expansion Package for STM32Cube
(UM2426).
UM2743
Cellular and end-to-end data plane connectivity setup
UM2743
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Rev 1
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