Datasheet

11.2 Nested Vector Interrupt Controller
33.5.6 Events
The events are connected to the Event System.
Related Links
24. EVSYS – Event System
33.5.7 Debug Operation
When the CPU is halted in debug mode the ADC will halt normal operation. The ADC can be forced to
continue operation during debugging.
33.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the peripheral access controller (PAC),
except the following register:
Interrupt Flag Status and Clear (INTFLAG) register
Optional write-protection by the Peripheral Access Controller (PAC) is denoted by the "PAC Write-
Protection" property in each individual register description.
PAC write-protection does not apply to accesses through an external debugger.
Related Links
11.6 PAC - Peripheral Access Controller
33.5.9 Analog Connections
I/O-pins AIN0 to AIN19 as well as the VREFA/VREFB reference voltage pin are analog inputs to the ADC.
33.5.10 Calibration
The BIAS and LINEARITY calibration values from the production test must be loaded from the NVM
Software Calibration Area into the ADC Calibration register (CALIB) by software to achieve specified
accuracy.
Related Links
10.3.2 NVM Software Calibration Area Mapping
33.6 Functional Description
33.6.1 Principle of Operation
By default, the ADC provides results with 12-bit resolution. 8-bit or 10-bit results can be selected in order
to reduce the conversion time.
The ADC has an oversampling with decimation option that can extend the resolution to 16 bits. The input
values can be either internal (e.g., internal temperature sensor) or external (connected I/O pins). The user
can also configure whether the conversion should be single-ended or differential.
33.6.2 Basic Operation
33.6.2.1 Initialization
Before enabling the ADC, the asynchronous clock source must be selected and enabled, and the ADC
reference must be configured. The first conversion after the reference is changed must not be used. All
SAM D21 Family
ADC – Analog-to-Digital Converter
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 894