NRF9160-SICA-R7 datasheet(200/400 Pages) NORDIC

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Peripherals

due to high source impedance and sampling jitter. For battery measurement, the DC errors are most

noticeable.

The ADC has a wide selection of gains controlled in the GAIN field of the CH[n].CONFIG register. If

CH[n].CONFIG.REFSEL=0, the input range of the ADC core is nominally ±0.6 V differential and the input

must be scaled accordingly.

The ADC has a temperature dependent offset. If the ADC is to operate over a large temperature range, we

recommend running CALIBRATEOFFSET at regular intervals. The CALIBRATEDONE event will be fired when

the calibration has been completed. Note that the DONE and RESULTDONE events will also be generated.

6.12.3 Analog inputs and channels

Up to eight analog input channels, CH[n](n=0..7), can be configured.

Any one of the available channels can be enabled for the ADC to operate in one-shot mode. If more than

one CH[n] is configured, the ADC enters scan mode.

An analog input is selected as a positive converter input if CH[n].PSELP is set, setting CH[n].PSELP also

enables the particular channel.

An analog input is selected as a negative converter input if CH[n].PSELN is set. The CH[n].PSELN register

will have no effect unless differential mode is enabled, see MODE field in CH[n].CONFIG register.

If more than one of the CH[n].PSELP registers is set, the device enters scan mode. Input selections in scan

mode are controlled by the CH[n].PSELP and CH[n].PSELN registers, where CH[n].PSELN is only used if the

particular scan channel is specified as differential, see MODE field in CH[n].CONFIG register.

6.12.4 Operation modes

The ADC input configuration supports one-shot mode, continuous mode and scan mode.

Note: Scan mode and oversampling cannot be combined.

The ADC indicates a single ongoing conversion via the register STATUS on page 219. During scan

mode, oversampling, or continuous modes, more than a single conversion take place in the ADC. As

consequence, the value reflected in STATUS register will toggle at the end of each single conversion.

6.12.4.1 One-shot mode

One-shot operation is configured by enabling only one of the available channels defined by CH[n].PSELP,

CH[n].PSELN, and CH[n].CONFIG registers.

Upon a SAMPLE task, the ADC starts to sample the input voltage. The CH[n].CONFIG.TACQ controls the

acquisition time.

A DONE event signals that one sample has been taken.

In this mode, the RESULTDONE event has the same meaning as DONE when no oversampling takes place.

Note that both events may occur before the actual value has been transferred into RAM by EasyDMA. For

more information, see EasyDMA on page 202.

6.12.4.2 Continuous mode

Continuous sampling can be achieved by using the internal timer in the ADC, or triggering the SAMPLE task

from one of the general purpose timers through the PPI system.

Care shall be taken to ensure that the sample rate fulfils the following criteria, depending on how many

channels are active:

fSAMPLE < 1/(tACQ + tconv)

4418_1315 v2.0

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