ANNA-B112 - System integration manual
UBX-18009821 - R09
System description
Page 10 of 66
C1-Public
Due to the low current consumption and wide voltage range of the ANNA-B112 module, a battery can
be used as a main supply. The capacity of the battery should be selected to match the application.
Care should be taken so that the battery can deliver the peak current required by the module. See the
ANNA-B112 data sheet [2]
for electrical specifications.
It is considered as best practice to have decoupling capacitors on the supply rails close to the
ANNA-B112 module, although depending on the design of the power routing on the host system,
capacitance might not be needed.
System function interfaces
1.5.1
Module reset
You can reset the ANNA-B112 module by applying a low level on the
RESET_N
input pin, which is
normally set high with an internal pull-up. This causes an “external” or “hardware” reset of the module.
The current parameter settings are not saved in the non-volatile memory of the module and a proper
network detach is not performed.
1.5.2
Internal temperature sensor
The radio chip in the ANNA-B112 module contains a temperature sensor used for over temperature
and under temperature shutdown.
⚠
The temperature sensor is located inside the radio chip and should not be used if an accurate
temperature reading of the surrounding environment is required.
Low power clock
The ANNA-B112 module uses a 32.768 kHz low power clock to enable different sleep modes. This
clock can be generated from an internal or external clock source.
Different options for generating the clock are listed below:
•
Internal oscillator
•
External crystal oscillator
•
External clock source
The u-connectXpress software automatically senses the clock input and uses the external crystal if
available; otherwise, it runs the internal oscillator. This automatic sense functionality will add
additional time during startup (about 1s). If the startup time is critical or more detailed settings are
needed, then set the low power clock settings using AT commands. See section1.6.4.
To fully utilize the low current consumption of the ANNA-B112 module, an external crystal or external
clock source is needed. The internal oscillator will increase the current consumption in sleep mode.
☞
An external crystal is required by the mesh variant of u-connectXpress as well as some 3
rd
party
SWs like for example Wirepas Mesh.
The following sections describe the different hardware options for the low power clock source and the
implications these choices on both the cost and performance of the ANNA-B112 module. For practical
guidance on how to configure the oscillator on nRF5 open CPU modules, see the application note [15].
1.6.1
External crystal
The ANNA-B112 has two input pins for connecting an external crystal as source for the low power
clock. This setup will enable ANNA-B112 to run with the lowest overall power consumption. Figure 1
shows the components used on the ANNA-B112 EVK.
