Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

875

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The ADC Controller can manage ADC conversions and Touchscreen measurement. On each trigger event the sequence
of ADC conversions is performed as described in 

Touchscreen measure frequency can be specified in number of trigger events by writing the TSFREQ parameter in the

. An internal counter counts triggers up to TSFREQ, and every time it rolls out, a

Touchscreen sequence is appended to the classic ADC conversion sequence (see 

Additionally the user can average multiple Touchscreen measures by writing the TSAV parameter in the 

. This can be 1, 2, 4 or 8 measures performed on consecutive triggers as illustrated in

 bellow. Consequently, the TSFREQ parameter must be greater or equal to the TSAV parameter.

As soon as the controller finishes the Touchscreen sequence, XRDY, YRDY and PRDY are set and can generate an
interrupt. These flags can be read in the 

. They are reset independently by reading in

ADC_XPOSR, ADC_YPOSR and ADC_PRESSR. for classic ADC conversions.

The 

 presents XPOS (V

X

 - V

Xmin

) on its LSB and XSCALE (V

XMAX

 - V

Xmin

) aligned

on the 16th bit.

The 

 presents YPOS (V

Y

 - V

Ymin

) on its LSB and YSCALE (V

YMAX

 - V

Ymin

) aligned

on the 16th bit.

To improve the quality of the measure, the user must calculate: XPOS/XSCALE and YPOS/YSCALE.

V

XMAX, 

V

Xmin, 

V

YMAX, 

and

 

V

Ymin

 are measured at the first start up of the controller. These values can change during use, so

it can be necessary to refresh them. Refresh can be done by writing ‘1’ in the CALIB field of the control register
(ADC_CR).

The 

 presents Z1 on its LSB and Z2 aligned on the 16th bit. See 

 to

know how use them.

Trigger event

ADC_SEL

XRDY

Read the

ADC_XPOSR

Read the

ADC_XPOSR

C

T

C

T

C

C

T

C

T

C

C

C:  Classic ADC Conversion Sequence     -     T:  Touchscreen Sequence 

YRDY

Read the

ADC_YPOSR

Read the

ADC_YPOSR