WM8311 datasheet(130/302 Pages) WOLFSON

130 / 302 page

WM8311

Pre-Production

PP, May 2012, Rev 3.1

130

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16425 (4029h)

Touch Control 2

TCH_5WIRE

Touch Panel control mode

0 = 4-wire

1 = 5-wire

TCH_ISEL

Pressure measurement current

select

0 = 200uA

1 = 400uA

Note - this applies to 4-wire mode

only

3:0

TCH_RPU [3:0]

0111

Pen-Down sensitivity (pull-up

resistor)

0000 = 64k (most sensitive)

0001 = 64k / 2

0010 = 64k / 3

0011 = 64k / 4

….

1111 = 64k / 16 (least sensitive)

Table 70 Touch Panel Configuration

19.3 TOUCH PANEL CONTROL

The Touch Panel is enabled by setting the TCH_ENA register bit. By default, the Touch Panel is not

enabled in the SLEEP state, but this can be selected using the TCH_SLPENA field.

The Touch Panel can be configured to issue a WAKE request when the ‘Pen Down’ is detected by

setting the TCH_PD_WK bit. This function is only supported when TCH_ENA = 1. Note that the

WAKE request may be generated regardless of the TCH_SLPENA setting.

The Touch Panel measurements can be initiated manually or automatically. For automatic operation,

the TCH_RATE register is set according to the required conversion rate, and measurements are

enabled by setting the TCH_CVT_ENA bit. For manual operation, the TCH_RATE register is set to

00h, and a set of measurements is initiated by setting the TCH_CVT_ENA bit. In manual mode, the

TCH_CVT_ENA bit is reset by the WM8311 after each set of measurements. (Note that the

measurement results are not available for readback until the Touch Panel Data interrupt is asserted,

as described in Section 19.5.)

Note that the Touch Panel measurements are interleaved with the AUXADC measurements, when

both are enabled. If an AUXADC measurement set is already in progress at the time when an Touch

Panel measurement is due, then the Touch Panel measurement will be delayed until after the

AXUADC measurement set has completed. This applies equally to Manual and to Automatic Touch

Panel modes.

The Touch Panel ‘Pen Down’ detection can be used to control measurements in automatic mode.

When TCH_PDONLY is set, then automatic conversions will only be scheduled when ‘Pen Down’ is

detected. In this mode, automatic conversions are suspended after a measurement has been made

for which ‘Pen Down’ is not detected. Automatic measurements are resumed when ‘Pen Down’ is

detected. Note that manual conversion commands are not affected by TCH_PDONLY.

For each Touch Panel measurement event (in Manual or Automatic modes), the WM8311 performs a

set of measurements encompassing all enabled input sources; the X-axis, Y-axis and Z-axis

measurements are enabled using the TCH_X_ENA, TCH_Y_ENA and TCH_Z_ENA register bits

respectively. To allow settling time between consecutive measurements, a programmable delay is

applied between the X, Y and Z-axis measurements; this is set using the TCH_DELAY field.

The control fields associated with initiating Touch Panel measurements are defined in Table 71.

WM8311 Datasheet(PDF) 130 Page - Wolfson Microelectronics plc

WM8311 Datasheet(HTML) 130 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL