WM8351 datasheet(170/330 Pages) WOLFSON

170 / 330 page

WM8351

Production Data

PD, April 2012, Rev 4.5

170

19.2 INITIATING AUXADC MEASUREMENTS

The AUXADC can measure voltages on four external pins, AUX1, AUX2, AUX3 and AUX4. It can also

measure voltages on the USB, LINE and BATT pins, and also the temperature sensor level. Each of

these 8 inputs can be independently selected or deselected as an AUXADC input. Whenever the

AUXADC is triggered, the AUXADC performs a measurement of each of the selected AUXADC

inputs. By default, none of the AUXADC inputs is selected. Therefore, the required inputs must be

enabled using the AUXADC_SELn bits prior to initiating an AUXADC measurement.

AUXADC measurements can be scheduled in a number of different ways, as determined by the

AUXADC_CTC register bit. In Polling Mode, a set of measurements is initiated by writing a logic ‘1’ to

the AUXADC_POLL bit. (This bit is then automatically reset once the measurements have been

completed.) In Continuous Mode, the WM8351 initiates a set of measurements at a time interval that

is determined by the AUXADC_CRATE field.

Additional control can be provided using a GPIO pin configured as a ‘MASK’ input (see Section 20).

The behaviour of the MASK input is selected using the AUXADC_MASKMODE register field - it can

be used to inhibit any measurements triggered by the Polling or Continuous modes, or else it can be

used as a hardware input to initiate a set of measurements.

Note that, when AUXADC_MASKMODE = 11, then AUXADC_CTC, AUXADC_POLL and

AUXADC_CRATE have no effect. The polarity of the MASK input can be adjusted to be active high or

active low using the GPn_CFG bits defined in Section 20, where ‘n’ identifies the particular GPIO pin

in use.

The control fields associated with initiating AUXADC measurements are defined in Table 115.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R144 (90h)

Digitiser Control

(1)

AUXADC_CTC

Continuous conversion mode:

0 = Polling mode

1 = Continuous mode

AUXADC_POLL

Writing “1” initiates a set of

measurements in polling mode

(AUXADC_CTC=0). This bit is

automatically reset after the

measurements are completed.

AUXADC_SEL8

AUXADC TEMP input select

0 = Disable TEMP measurement

1 = Enable TEMP measurement

AUXADC_SEL7

AUXADC BATT input select

0 = Disable BATT measurement

1 = Enable BATT measurement

AUXADC_SEL6

AUXADC LINE input select

0 = Disable LINE measurement

1 = Enable LINE measurement

AUXADC_SEL5

AUXADC USB input select

0 = Disable USB measurement

1 = Enable USB measurement

AUXADC_SEL4

AUXADC AUX4 input select

0 = Disable AUX4 measurement

1 = Enable AUX4 measurement

AUXADC_SEL3

AUXADC AUX3 input select

0 = Disable AUX3 measurement

1 = Enable AUX3 measurement

AUXADC_SEL2

AUXADC AUX2 input select

0 = Disable AUX2 measurement

1 = Enable AUX2 measurement

AUXADC_SEL1

AUXADC AUX1 input select

0 = Disable AUX1 measurement

1 = Enable AUX1 measurement

WM8351 Datasheet(PDF) 170 Page - Wolfson Microelectronics plc

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