u-blox EVK-NINA-B50, User Manual

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EVK-NINA-B50 - User guide
UBX-23007761 - R02 Setting up the evaluation board Page 10 of 37
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An external debugger is useful when powering the evaluation board with a CR2032 coin cell battery,
or through the J5 external power supply connector. It is also useful when the MCU interface has been
disconnected from the NINA-B50 module using the jumpers on the J19 header.
SEGGER J-Link software [5] is necessary to debug with the onboard J-Link hardware on the EVK-
NINA-B50.
2.3 Measuring current consumption
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Before starting the current consumption measurement, go through the Board configuration and
define your configuration preferences. Find out what NINA signals must subsequently be
isolated. The J22 jumper pins 1 and 3 must be removed to measure the current consumption.
Figure 5 shows some suggestions for connecting the various instruments when measuring module
current consumption.
Using an ammeter
An ammeter should be connected in series with the power source and whatever is being measured. In
this way, current can be measured when the NINA module is supplied from either the onboard 3.3 V
regulator or an external supply.
Using a voltmeter
The EVK board must be modified before module current can be measured with a voltmeter.
To modify the board, solder a low resistance, high tolerance, 0402 sized resistor to the footprint
labeled R6. This resistor replaces the jumper normally positioned between J22 pins 1 and 3. Any
current passing through the resistor produces a voltage across its terminals. Measure this voltage
with the voltmeter and calculate the current using O
hm’ s law.
Using an external power supply or power analyzer
Connect the terminals of the instrument to the EVK pins, as shown in Figure 5 . An ammeter can also
be added in series.
Since the external voltage of any connected instrument can never perfectly match the 3.3 V
generated by the EVK, some small current leakage is apparent whenever the signal from the NINA
module is connected to an EVK peripheral. The leakage is
typically in the order of ’s of nano amps.
To reduce leakage current, use a second external power channel to supply the EVK peripherals. This
second channel must also be used to enable PC communication when using NINA supply voltages
other than 3.3 V.