Data Sheet

861
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181G–SAM-D21_Datasheet–09/2015
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.
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.
z Bits 3:0 – REFSEL[3:0]: Reference Selection
These bits select the reference for the ADC according to Table 32-7.
Table 32-7. Reference Selection
Bit 76543210
REFCOMP
REFSEL[3:0]
Access R/W R R R R/W R/W R/W R/W
Reset00000000
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