WM8310 datasheet(122/291 Pages) WOLFSON

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WM8310

Pre-Production

PP, May 2012, Rev 3.1

122

18.3 AUXADC READBACK

Measured data from the AUXADC is read via the AuxADC Data Register (R16429), which contains

two fields. The AUXADC Data Source is indicated in the AUX_DATA_SRC field; the associated

measurement data is contained in the AUX_DATA field.

Reading from the AuxADC Data Register returns a 12-bit code which represents the most recent

AUXADC measurement on the associated channel. It should be noted that every time an AUXADC

measurement is written to the AuxADC Data Register, the previous data is overwritten - the host

processor should ensure that data is read from this register before it is overwritten. The AUXADC

interrupts can be used to indicate when new data is available - see Section 18.5.

The 12-bit AUX_DATA field can be equated to the actual voltage (or temperature) according to the

following equations, where AUX_DATA is regarded as an unsigned integer:

Battery Temperature measurement varies according to the selected NTC thermistor component.

In a typical application, it is anticipated that the AUXADC Interrupts would be used to control the

AUXADC readback - the host processor should read the AUXADC Data Register in response to the

AUXADC Interrupt event. See Section 18.5 for details of AUXADC Interrupts. In Automatic AUXADC

mode, the processor should complete this action before the next measurement occurs, in order to

avoid losing any AUXADC samples. In Manual conversion mode, the interrupt signal provides

confirmation that the commanded measurement has been completed.

The control fields associated with initiating AUXADC readback are defined in Table 66.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16429

(402Dh)

AuxADC Data

15:12

AUX_DATA_SRC

[3:0]

000

AUXADC Data Source

0 = Reserved

1 = AUXADCIN1

2 = AUXADCIN2

3 = AUXADCIN3

4 = AUXADCIN4

5 = Chip Temperature

6 = Battery Temperature

7 = SYSVDD voltage

8 = USB voltage

9 = BATT voltage

10 = WALL voltage

11 = Reserved

12 = Reserved

13 = Reserved

14 = Reserved

15 = Reserved

11:0

AUX_DATA [11:0]

000h

AUXADC Measurement Data

Voltage (mV) = AUX_DATA x 1.465

ChipTemp (

C) = (498 - AUX_DATA) /

1.09

BattTemp (

C) = (value is dependent on

NTC thermistor)

Table 66 AUXADC Readback

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