Integration Manual

NINA-B4 series - System integration manual
UBX-19052230 - R09 Functional description Page 13 of 60
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1.8.2 NINA-B41 pins
The u-connectXpress software running on NINA-B41 modules has fixed pin multiplexing that
implements a given set of features, like the UART connection. The pin assignments for NINA-B41 are
shown in Figure 5.
Figure 5: NINA-B41 pin assignments
☞ For more information about the pin assignments, see also the NINA-B41 series data sheet [3].
1.9 Low power clock
NINA-B4 modules use a 32.768 kHz low power clock to enable different sleep modes.
The clock can be generated from either of the following sources:
• Internal oscillator
• External crystal (LFXO)
• External clock source such as a crystal oscillator (TCXO)
The u-connectXpress software automatically senses the clock input and uses the source from the
external crystal – if one is available. Otherwise, the software uses the source from the internal
oscillator. This automatic sense functionality adds some additional time delay during startup (~1s).
To reach the lowest sleep current consumption of the NINA-B4 module, an external crystal or external
clock source shall be used. The internal oscillator gives higher sleep current but of course a leaner
BOM. For more information about sleep and other power modes, see the respective data sheet [2] [3].
Sections 1.9.1 to 1.9.3 describe the different hardware options for the low power clock source and
explain the implications the clock choices have on both the cost and performance of NINA-B4
modules. For practical guidance on how to configure the oscillator on nRF5 open CPU modules, see
also reference [21].
1.9.1 External crystal
NINA-B4 modules have two input pins for connecting an external low-frequency crystal (LXFO) as
source for the low power clock. This setup enables NINA-B4 modules to run with the lowest overall
power consumption.