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.

This is not limited to a single peripheral, but extends across multiple hardware peripherals.

The following peripherals are used by this module:

The following devices can use this module:

The outline of this documentation is as follows:

Prerequisites

There are no prerequisites for this module.

Module Overview

The System driver provides a collection of interfaces between the user application logic, and the core device functionality (such as clocks, reset cause determination, etc.) that is required for all applications. It contains a number of sub-modules that control one specific aspect of the device:

System Core (this module)
System Clock Control (sub-module)
System Interrupt Control (sub-module)
System Pin Multiplexer Control (sub-module)

Voltage References

The various analog modules within the SAM devices (such as AC, ADC, and DAC) require a voltage reference to be configured to act as a reference point for comparisons and conversions.

The SAM devices contain multiple references, including an internal temperature sensor and a fixed band-gap voltage source. When enabled, the associated voltage reference can be selected within the desired peripheral where applicable.

System Reset Cause

In some applications there may be a need to execute a different program flow based on how the device was reset. For example, if the cause of reset was the Watchdog timer (WDT), this might indicate an error in the application, and a form of error handling or error logging might be needed.

For this reason, an API is provided to retrieve the cause of the last system reset, so that appropriate action can be taken.

Sleep Modes

The SAM devices have several sleep modes. The sleep mode controls which clock systems on the device will remain enabled or disabled when the device enters a low power sleep mode. The table below lists the clock settings of the different sleep modes.

SAM Device Sleep Modes
Sleep mode	CPU clock	AHB clock	APB clocks	Clock sources	System clock	32KHz	Reg mode	RAM mode
Idle 0	Stop	Run	Run	Run	Run	Run	Normal	Normal
Idle 1	Stop	Stop	Run	Run	Run	Run	Normal	Normal
Idle 2	Stop	Stop	Stop	Run	Run	Run	Normal	Normal
Standby	Stop	Stop	Stop	Stop	Stop	Stop	Low Power	Source/Drain biasing

Before entering device sleep, one of the available sleep modes must be set. The device will automatically wake up in response to an interrupt being generated or upon any other sleep mode exit condition.

Some peripheral clocks will remain enabled during sleep, depending on their configuration. If desired, the modules can remain clocked during sleep to allow them continue to operate while other parts of the system are powered down to save power.

Special Considerations

Most of the functions in this driver have device specific restrictions and caveats; refer to your device datasheet.

Extra Information

For extra information, see Extra Information for SYSTEM Driver. This includes:

Examples

For SYSTEM module related examples, refer to the sub-modules listed in the Module Overview.

API Overview

Enumerations
enum	system_reset_cause { SYSTEM_RESET_CAUSE_SOFTWARE = PM_RCAUSE_SYST, SYSTEM_RESET_CAUSE_WDT = PM_RCAUSE_WDT, SYSTEM_RESET_CAUSE_EXTERNAL_RESET = PM_RCAUSE_EXT, SYSTEM_RESET_CAUSE_BOD33 = PM_RCAUSE_BOD33, SYSTEM_RESET_CAUSE_BOD12 = PM_RCAUSE_BOD12, SYSTEM_RESET_CAUSE_POR = PM_RCAUSE_POR }
	Reset causes of the system. More...

enum	system_sleepmode { SYSTEM_SLEEPMODE_IDLE_0, SYSTEM_SLEEPMODE_IDLE_1, SYSTEM_SLEEPMODE_IDLE_2, SYSTEM_SLEEPMODE_STANDBY }
	Device sleep modes. More...

enum	system_voltage_reference { SYSTEM_VOLTAGE_REFERENCE_TEMPSENSE, SYSTEM_VOLTAGE_REFERENCE_BANDGAP }
	Voltage references within the device. More...

System Debugger
static bool	system_is_debugger_present (void)
	Check if debugger is present. More...

System Identification
static uint32_t	system_get_device_id (void)
	Retrieve the device identification signature. More...

System Initialization
void	system_init (void)
	Initialize system. More...

Voltage References
static void	system_voltage_reference_enable (const enum system_voltage_reference vref)
	Enable the selected voltage reference. More...

static void	system_voltage_reference_disable (const enum system_voltage_reference vref)
	Disable the selected voltage reference. More...

Device Sleep Control
static enum status_code	system_set_sleepmode (const enum system_sleepmode sleep_mode)
	Set the sleep mode of the device. More...

static void	system_sleep (void)
	Put the system to sleep waiting for interrupt. More...

Reset Control
static void	system_reset (void)
	Reset the MCU. More...

static enum system_reset_cause	system_get_reset_cause (void)
	Return the reset cause. More...

enum system_reset_cause

Reset causes of the system.

List of possible reset causes of the system.

Enumerator
SYSTEM_RESET_CAUSE_SOFTWARE	The system was last reset by a software reset.
SYSTEM_RESET_CAUSE_WDT	The system was last reset by the watchdog timer.
SYSTEM_RESET_CAUSE_EXTERNAL_RESET	The system was last reset because the external reset line was pulled low.
SYSTEM_RESET_CAUSE_BOD33	The system was last reset by the BOD33.
SYSTEM_RESET_CAUSE_BOD12	The system was last reset by the BOD12.
SYSTEM_RESET_CAUSE_POR	The system was last reset by the POR (Power on reset)

enum system_sleepmode

Device sleep modes.

List of available sleep modes in the device. A table of clocks available in different sleep modes can be found in Sleep Modes.

Enumerator
SYSTEM_SLEEPMODE_IDLE_0	IDLE 0 sleep mode.
SYSTEM_SLEEPMODE_IDLE_1	IDLE 1 sleep mode.
SYSTEM_SLEEPMODE_IDLE_2	IDLE 2 sleep mode.
SYSTEM_SLEEPMODE_STANDBY	Standby sleep mode.

enum system_voltage_reference

Voltage references within the device.

List of available voltage references (VREF) that may be used within the device.

Enumerator
SYSTEM_VOLTAGE_REFERENCE_TEMPSENSE	Temperature sensor voltage reference.
SYSTEM_VOLTAGE_REFERENCE_BANDGAP	Bandgap voltage reference.

static uint32_t system_get_device_id ( void )

inlinestatic

Retrieve the device identification signature.

Retrieves the signature of the current device.

Returns: Device ID signature as a 32-bit integer.

static enum system_reset_cause system_get_reset_cause ( void )

inlinestatic

Return the reset cause.

Retrieves the cause of the last system reset.

Returns: An enum value indicating the cause of the last system reset.

void system_init ( void )

Initialize system.

This function will call the various initialization functions within the system namespace. If a given optional system module is not available, the associated call will effectively be a NOP (No Operation).

Currently the following initialization functions are supported:

System clock initialization (via the SYSTEM CLOCK sub-module)
Board hardware initialization (via the Board module)
Event system driver initialization (via the EVSYS module)
External Interrupt driver initialization (via the EXTINT module)

References system_board_init(), and system_clock_init().

Referenced by main().

static bool system_is_debugger_present ( void )

inlinestatic

Check if debugger is present.

Check if debugger is connected to the onboard debug system (DAP).

Returns: A bool identifying if a debugger is present.

Return values

true	Debugger is connected to the system
false	Debugger is not connected to the system

Referenced by _usart_set_config().

static void system_reset ( void )

inlinestatic

Reset the MCU.

Resets the MCU and all associated peripherals and registers, except RTC, all 32KHz sources, WDT (if ALWAYSON is set) and GCLK (if WRTLOCK is set).

static enum status_code system_set_sleepmode ( const enum system_sleepmode sleep_mode )

inlinestatic

Set the sleep mode of the device.

Sets the sleep mode of the device; the configured sleep mode will be entered upon the next call of the system_sleep() function.

For an overview of which systems are disabled in sleep for the different sleep modes, see Sleep Modes.

Parameters

[in] sleep_mode Sleep mode to configure for the next sleep operation

Return values

STATUS_OK	Operation completed successfully
STATUS_ERR_INVALID_ARG	The requested sleep mode was invalid or not available

References _SYSTEM_MCU_REVISION_D, _SYSTEM_MCU_REVISION_E, STATUS_ERR_INVALID_ARG, STATUS_OK, SYSTEM_SLEEPMODE_IDLE_0, SYSTEM_SLEEPMODE_IDLE_1, SYSTEM_SLEEPMODE_IDLE_2, and SYSTEM_SLEEPMODE_STANDBY.

static void system_sleep ( void )

inlinestatic

Put the system to sleep waiting for interrupt.

Executes a device DSB (Data Synchronization Barrier) instruction to ensure all ongoing memory accesses have completed, then a WFI (Wait For Interrupt) instruction to place the device into the sleep mode specified by system_set_sleepmode until woken by an interrupt.

static void system_voltage_reference_disable ( const enum system_voltage_reference vref )

inlinestatic

Disable the selected voltage reference.

Disables the selected voltage reference source.

Parameters

[in] vref Voltage reference to disable

References Assert, SYSTEM_VOLTAGE_REFERENCE_BANDGAP, and SYSTEM_VOLTAGE_REFERENCE_TEMPSENSE.

static void system_voltage_reference_enable ( const enum system_voltage_reference vref )

inlinestatic

Enable the selected voltage reference.

Enables the selected voltage reference source, making the voltage reference available on a pin as well as an input source to the analog peripherals.

Parameters

[in] vref Voltage reference to enable

References Assert, SYSTEM_VOLTAGE_REFERENCE_BANDGAP, and SYSTEM_VOLTAGE_REFERENCE_TEMPSENSE.

Microchip® Advanced Software Framework

Prerequisites

Module Overview

Voltage References

System Reset Cause

Sleep Modes

Special Considerations

Extra Information

Examples

API Overview

Enumerations

System Debugger

System Identification

System Initialization

Voltage References

Device Sleep Control

Reset Control