Atmel SAM4S Xplained Pro Starter Kit Atmel ATSAM4S-XSTK ATSAM4S-XSTK Data Sheet

 985

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

The conversion is performed on a full range between 0V and the reference voltage pin ADVREF. Analog inputs between
these voltages convert to values based on a linear conversion.

The ADC supports 10-bit or 12-bit resolutions. The 10-bit selection is performed by setting the LOWRES bit in the ADC
Mode Register (ADC_MR). By default, after a reset, the resolution is the highest and the DATA field in the data registers
is fully used. By setting the LOWRES bit, the ADC switches to the lowest resolution and the conversion results can be
read in the lowest significant bits of the data registers. The two highest bits of the DATA field in the corresponding
ADC_CDR register and of the LDATA field in the ADC_LCDR register read 0. 

Moreover, when a PDC channel is connected to the ADC, 12-bit or 10-bit resolution sets the request size to 16 bits.

When a conversion is completed, the resulting 12-bit digital value is stored in the Channel Data Register (ADC_CDRx) of
the current channel and in the ADC Last Converted Data Register (ADC_LCDR). By setting the TAG option in the
ADC_EMR, the ADC_LCDR presents the channel number associated to the last converted data in the CHNB field.

The channel EOC bit in the Status Register (ADC_SR) is set and the DRDY is set. In the case of a connected PDC
channel, DRDY rising triggers a data request. In any case, either EOC and DRDY can trigger an interrupt.

Reading one of the ADC_CDR registers clears the corresponding EOC bit. Reading ADC_LCDR clears the DRDY bit.

ADCClock

LCDR

ADC_ON

Trigger event (Hard or Soft)

ADC_SEL

DRDY

ADC_Start

CH0

CH1

CH0

CH2

CH1

CH3

CH2

Transfer Period

Transfer Period

Transfer Period

Start Up

Time

&

Tracking

of CH0

Conversion

of CH0

&

Tracking

of CH1

Conversion

of CH1

&

Tracking

of CH2

Conversion

of CH2

&

Tracking

of CH3

Read the

ADC_LCDR

Commands

from controller

to analog cell