WM9714LGEFLSLASHV datasheet(55/94 Pages) WOLFSON

55 / 94 page

Pre-Production

WM9714L

PP Rev 3.0 June 2006

In a polling routine, the CPU starts each measurement individually by writing to the POLL bit (register

74h, bit 9). This bit automatically resets itself when the measurement is completed.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

POLL

Writing “1” initiates a measurement.

(when CTC is not set)

74h

CTC

0: Polling mode

1: Continuous mode (for DMA)

76h

9:8

Continuous mode rate (DEL C 1111)

00: 93.75 Hz (every 512 AC-Link frames)

01: 120 Hz (every 400 AC-Link frames)

10: 153.75 Hz (every 312 AC-Link frames)

11: 187.5Hz (every 256 AC-Link frames)

Continuous mode “fast rate” (DEL = 1111)

00: 8 kHz (every six AC-Link frames)

01: 12 kHz (every four AC-Link frames)

10: 24 kHz (every other AC-Link frame)

11: 48 kHz (every AC-Link frame)

Table 47 AUX ADC Control (Initiation of Measurements)

In continuous mode (CTC = 1), the WM9714L autonomously initiates measurements (or sets of

measurements) at the rate set by CR, and supplies the measured data to the CPU on one of the

unused AC’97 time slots. DMA-enabled CPUs can write the data directly into a FIFO without any

intervention by the CPU core. This reduces CPU loading and speeds up the execution of user

programs in handheld systems.

Note that the measurement frequency in continuous mode is also affected by the DEL bits. The

faster rates achieved when DEL = 1111 may be useful when the ADC is used for multiple

measurements.

MEASUREMENT TYPES

The ADCSEL control bits determine which type of measurement is performed (see below).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

POLL

Writing “1” initiates a measurement.

(when CTC is not set)

CTC

0: Polling mode

1: Continuous mode (for DMA)

ADCSEL_AUX4

Enable COMP1/AUX4 measurement

(pin32). NB: Only one of bits[7:4] should

be set.

ADCSEL_AUX3

Enable COMP1/AUX3 measurement

(pin31) . NB: Only one of bits[7:4] should

be set.

ADCSEL_AUX2

Enable COMP1/AUX2 measurement

(pin30) . NB: Only one of bits[7:4] should

be set.

74h

ADCSEL_AUX1

Enable COMP1/AUX1 measurement

(pin29) . NB: Only one of bits[7:4] should

be set.

Table 48 AUX ADC Control (Measurement Types)

The WM9714L performs a single measurement – either in polling mode or continuously, as indicated

by the CTC bit. The type of measurement is specified by the ADCSEL[7:4] bits. Only one of the

ADCSEL[7:4] bits should be set.

WM9714LGEFL/V Datasheet(PDF) 55 Page - Wolfson Microelectronics plc

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