372
8331B–AVR–03/12
Atmel AVR XMEGA AU
28.16.3
REFCTRL – Reference Control register
• Bit 7 – 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.
• Bits 6:4 – REFSEL[2:0]: Reference Selection
These bits selects the reference for the ADC according to
• Bit 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 1 – BANDGAP: Bandgap Enable
Setting this bit enables the bandgap for ADC measurement. Note that if any other functions are
already using the bandgap, this bit does not need to be set when the internal 1.00V reference is
used for another ADC, the DAC or if the brownout detector is enabled.
• Bit 0 – TEMPREF: Temperature Reference Enable
Setting this bit enables the temperature sensor for ADC measurement.
28.16.4
EVCTRL – Event Control register
• Bit 7:6 – SWEEP[1:0]: Channel Sweep
These bits control which ADC channels are included in a channel sweep triggered by the event
system or when in free running mode. See
Bit
7
6
5
4
3
2
1
0
–
REFSEL[2:0]
–
–
BANDGAP
TEMPREF
REFCTRL
Read/Write
R
R/W
R/W
R/W
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Table 28-5.
ADC reference selection.
REFSEL[2:0]
Group Configuration
Description
000
INT1V
10/11 of bandgap (1.0V)
001
INTVCC
V
CC
/1.6
010
AREFA
External reference from AREF pin on PORT A
011
AREFB
External reference from AREF pin on PORT B
100
INTVCC2
V
CC
/2
101 - 111
Reserved
Bit
7
6
5
4
3
2
1
0
SWEEP[1:0]
EVSEL[2:0]
EVACT[2:0]
EVCTRL
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
