NINA-B3 series - System integration manual
UBX-17056748 - R13 System description Page 13 of 72
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1.8.1 Analog interfaces
Eight out of the 38 digital GPIOs can be multiplexed to analog functions. The following analog
functions are available for use:
• 1x 8-channel ADC
• 1x Analog comparator*
• 1x Low-power analog comparator*
*Only one of the comparators can be used simultaneously.
ADC
The Analog to Digital Converter (ADC) can sample up to 200 kHz using different inputs as sample
triggers. Both one-shot conversion and continuous sampling are supported. Table 5 shows the
sample speed in correlation to the maximum source impedance. It supports 8/10/12-bit resolution.
The ADC includes 14-bit resolution if oversampling is used. Any of the 8 analog inputs can be used
both as single-ended inputs and as differential pairs for measuring the voltage across them.
The ADC supports the full 0 V to VCC input range. If the sampled signal level is much lower than VCC,
it is possible to lower the input range of the ADC to encompass the desired signal and obtain a higher
effective resolution. Continuous sampling can be configured to sample at a configurable time interval,
or at different internal or external events, without CPU involvement.
Table 5: Acquisition vs. source impedance
Comparator
The comparator compares voltages from any analog pin with different references as shown in Table
6. It supports the full 0 V to VCC input range and can generate different software events to the rest
of the system. The comparator can operate in the one of the following two modes as explained below
- Single-ended or Differential:
• Single-ended Mode: A single reference level or an upper and lower hysteresis selectable from a
64-level reference ladder with a range from 0 V to VREF as described in Table 6.
• Differential Mode: Two analog pin voltage levels are compared, optionally with a 50 mV hysteresis
Low power comparator
The low-power comparator operates in the same way as the normal comparator, with reduced
functionality. It can be used during system OFF modes as a wake-up source.
Analog pin options
Table 6 shows the supported connections of the analog functions.
☞ An analog pin may not be simultaneously connected to multiple functions.
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