WM9713L datasheet(74/133 Pages) CIRRUS

74 / 133 page

WM9713L

Rev 4.0

When operating in co-ordinate mode (COO=1) there will be 3 results to read back from each set of

measurements

– X, Y, and the third additional measurement. After the co-ordinate set has finished

the X result will be present in register 7Ah. Once this has been read back by the user the Y result will

overwrite register 7Ah, as indicated by ADCSRC. Finally, after the Y result has been read back, the

result of the third, additional, measurement will become present in 7Ah, again indicated by ADCSRC.

To avoid losing data that has not yet been read, the WM9713L can delay overwriting register 7Ah with

new conversions until the old data has been read. This function is enabled using the WAIT bit, and

applies to both single and co-ordinate conversion mode.

The flow diagram in Figure 32 shows the timing of touchpanel conversions, and data readback from

Poll (74h)

Reset

Poll (74h) Set

X Measurement(1)

Y Measurement(2)

Read Data

This occurs when user sets

POLL - or automatically when CTC=1

COO=1

COO=0

Measurement(3)

as described by

ADCSEL (74h)

ADCSELL!=000_0000

ADCSELL=000_0000

ADA goes high

ADA remains high until data has been

read from a register or sent out on an

AC-LINK slot (dependent on value of

SLEN)

User reads back single conversion (CO=0)

OR 1,2,3 in sequential order (CO=1)

from register 7Ah

POLL (74h)

Starts a single measurement

CTC (74h)

Starts a co-ordinate measurement at specified conversion rate

COO (74h)

Enables Co-ordinate mode

ADCSEL (74H)

Specifies the type of measurement to be made

Figure 32 Touchpanel Conversion Flow Diagram

WM9713L Datasheet(PDF) 74 Page - Cirrus Logic

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