371
8331B–AVR–03/12
Atmel AVR XMEGA AU
• Bit 6:5 – CURRLIMIT[1:0]: Current Limitation
These bits can be used to limit the current consumption of the ADC by reducing the maximum
ADC sample rate. The available settings are shown in
. The indicated
current limitations are nominal values. Refer to the device datasheet for actual current limitation
for each setting.
• Bit 4 – CONVMODE: Conversion Mode
This bit controls whether the ADC will work in signed or unsigned mode. By default, this bit is
cleared and the ADC is configured for unsigned mode. When this bit is set, the ADC is config-
ured for signed mode.
• Bit 3 – FREERUN: Free Running Mode
When the bit is set to one, the ADC is in free running mode and the ADC channels defined in the
EVCTRL register are swept repeatedly.
• Bit 2:1 – RESOLUTION[1:0]: Conversion Result Resolution
These bits define whether the ADC completes the conversion at 12- or 8-bit result resolution.
They also define whether the 12-bit result is left or right adjusted within the 16-bit result regis-
ters. See
for possible settings.
• Bit 0 - Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write
this bit to zero when this register is written.
Table 28-2.
Gain stage impedance mode.
IMPMODE
Group Configuration
Description
0
HIGHIMP
For high-impedance sources; charge will remain on input
1
LOWIMP
For low impedance sources
Table 28-3.
ADC current limitations.
CURRLIMIT[1:0]
Group Configuration
Description
00
NO
No limit
01
LOW
Low current limit, max. sampling rate 1.5MSPS
10
MED
Medium current limit, max. sampling rate 1MSPS
11
HIGH
High current limit, max. sampling rate 0.5MSPS
Table 28-4.
ADC conversion result resolution.
RESOLUTION[1:0]
Group Configuration
Description
00
12BIT
12-bit result, right adjusted
01
Reserved
10
8BIT
8-bit result, right adjusted
11
LEFT12BIT
12-bit result, left adjusted