Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
849
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
32.8.2 Reference Control
Name:
REFCTRL
Offset:
0x01
Reset:
0x00
Property:
Write-Protected
z
Bit 7 – REFCOMP: Reference Buffer Offset Compensation Enable
The accuracy of the gain stage can be increased by enabling the reference buffer offset compensation. This will
decrease the input impedance and thus increase the start-up time of the reference.
0: Reference buffer offset compensation is disabled.
1: Reference buffer offset compensation is enabled.
The accuracy of the gain stage can be increased by enabling the reference buffer offset compensation. This will
decrease the input impedance and thus increase the start-up time of the reference.
0: Reference buffer offset compensation is disabled.
1: Reference buffer offset compensation is enabled.
z
Bits 6:4 – 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. These bits will always return zero when read.
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. These bits will always return zero when read.
z
Bits 3:0 – REFSEL[3:0]: Reference Selection
These bits select the reference for the ADC according to
These bits select the reference for the ADC according to
Table 32-7. Reference Selection
Bit
7
6
5
4
3
2
1
0
REFCOMP
REFSEL[3:0]
Access
R/W
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
REFSEL[3:0]
Name
Description
0x0
INT1V
1.0V voltage reference
0x1
INTVCC0
1/1.48 VDDANA
0x2
INTVCC1
1/2 VDDANA (only for VDDANA > 2.0V)
0x3
VREFA
External reference
0x4
VREFB
External reference
0x5-0xF
Reserved