 User Interface | Human interface on SAM L21 Xplained Pro: |
| Implementation of UHC | Internal implementation |
| USB Host Driver Implement (UHD) | USB low-level driver for USB Host mode |
| SAM Serial USART (SERCOM USART) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the SERCOM module in its USART mode to transfer or receive USART data frames |
 Compiler abstraction layer and code utilities | Compiler abstraction layer and code utilities for Cortex-M0+ based Atmel SAM devices |
 Status Codes | |
| Preprocessor - Macro Recursion | |
| Preprocessor - Macro Repeat | |
| Preprocessor - Stringize | |
 Preprocessor - Token Paste | |
| Global interrupt management | This is a driver for global enabling and disabling of interrupts |
| Deprecated interrupt definitions | |
| Atmel part identification macros | This collection of macros identify which series and families that the various Atmel parts belong to |
| AVR UC3 parts | |
| AVR XMEGA parts | |
| megaAVR parts | |
| SAM parts | |
| SAM System (SYSTEM) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the device's system relation functionality, necessary for the basic device operation |
| SAM System Clock Management (SYSTEM CLOCK) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the device's clocking related functions |
| SAM System Interrupt (SYSTEM INTERRUPT) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of internal software and hardware interrupts/exceptions |
| SAM System Pin Multiplexer (SYSTEM PINMUX) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the device's physical I/O Pins, to alter the direction and input/drive characteristics as well as to configure the pin peripheral multiplexer selection |
| Sleep manager | The sleep manager is a service for ensuring that the device is not put to sleep in deeper sleep modes than the system (e.g., peripheral drivers, services or the application) allows at any given time |
| USB Host Driver (UHD) | The UHD driver provides a low-level abstraction of the host controller hardware |
| USB Host Interface (UHI) | The UHI provides a common API for all classes, and this is used by UHC for the main control of USB host interface |
 UHI for Communication Device Class | Common APIs used by high level application to use this USB host class |
 Implementation of UHI Communication Device Class | Class internal implementation |
| Interface with USB Host Core (UHC) | Define and functions required by UHC |
| SAM Universal Serial Bus (USB) | The Universal Serial Bus (USB) module complies with the USB 2.1 specification |
| SAM External Interrupt (EXTINT) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of external interrupts generated by the physical device pins, including edge detection |
| SAM Port (PORT) Driver | This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the device's General Purpose Input/Output (GPIO) pin functionality, for manual pin state reading and writing |
| USB Stack | This stack includes the USB Device Stack, USB Host Stack and common definitions |
| USB dual role driver | USB low-level driver for dual role features |
| Atmel USB Identifiers | This module defines Atmel PID and VIDs constants |
| USB Protocol Definitions | This module defines constants and data structures provided by the USB 2.0 specification |
| Communication Device Class Definitions | |
| Generic board support | The generic board support module includes board-specific definitions and function prototypes, such as the board initialization function |
| SAM L21 Xplained Pro board | |
| Features | Symbols that describe features and capabilities of the board |
1.8.5