WM9713 datasheet(67/111 Pages) WOLFSON

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Preliminary Technical Data

WM9713L

PTD, March 2004, Rev 2.2

CONVERSION RATE

As stated previously the conversion rate is specified by the CR bits (reg 76h).

CR may be set to 93.75Hz (every 512 AC-Link Frames), 120Hz (every 400 AC-Link Frames),

153.75Hz (every 312 AC-Link frames) or 187.5Hz (every 256 AC-Link frames).

If only one ADRSEL[7:1] bit is set then each individual conversion occurs at the rate specified by

CR.

If multiple ADRSEL[7:1] bits are set then the complete set of conversions requested is completed at

the rate specified by CR.

DATA READBACK

This data is stored in register 7Ah, and can be retrieved by reading the register in the usual manner

(see AC-Link Interface section). Additionally, the data can also be passed to the controller on one of

the AC-Link time slots not used for audio functions.

The output data word of the touchpanel interface consists of three parts:

•

Pen Status (1 bit) – this is also passed to the GPIO logic block, which can be

programmed to generate an interrupt and/or wake up the WM9713L on pen down

(see GPIO and Interrupt Control).

•

Output data from the touchpanel ADC (12 bits)

•

ADCSRC: 3 additional bits that indicate the source of the ADC data. In co-ordinate

mode (COO = ‘1’), the WM9713L schedules different types of measurements

autonomously and so these register bits may be required.

If the data is being read back using the polling method, there are several ways to determine when a

measurement has finished:

•

Reading back the POLL bit. If it has been reset to ‘0’, then the measurement has finished.

•

Monitoring the ADA signal, see GPIO and interrupt section. ADA goes high after every

single conversion. If operating in co-ordinate mode (COO=1) then ADA goes high after

every group of 3 conversions.

•

Reading back 7Ah until the new data appears

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