Low-level interface to the ResetReason of a target. More...

Modules
	ResetReason HAL tests
	Greentea tests for the ResetReason HAL.

Enumerations

Functions
reset_reason_t	hal_reset_reason_get (void)
	Fetch the reset reason for the last system reset. More...

uint32_t	hal_reset_reason_get_raw (void)
	Fetch the raw platform specific reset reason register value. More...

void	hal_reset_reason_clear (void)
	Clear the reset reason from registers. More...

Detailed Description

Low-level interface to the ResetReason of a target.

This module provides a platform-independent method of checking the cause of the last system reset.

Defined behavior

The function hal_reset_reason_clear clears the ResetReason registers for the next system boot.
By the time the user calls hal_reset_reason_get to read the value, some other part of the application may have cleared the value. Therefore, though there may have been a reset reason in the registers when the system started, the reason may not be available when the user comes to check it.

Undefined behavior

There is no guarantee that the function hal_reset_reason_get will return the same value when you call it repeatedly. Store the value for later use instead of calling the function repeatedly.
The function hal_reset_reason_clear may not clear the ResetReason register in time for the next system boot.

Notes

The contents of the targets ResetReason register may be cleared by some subsystem before it first gets called. This returns a RESET_REASON_UNKNOWN value to the user. To avoid this, the user should call the ResetReason API as early as possible at boot time.
If the target doesn't support clearing reset registers, hal_reset_reason_get seems to erroneously return a reset reason even after clearing.

Enumeration Type Documentation

enum reset_reason_t

Definitions of different reset reasons.

Enumerator
RESET_REASON_POWER_ON	Set when power is initially applied to the board. The power-on-reset circuit causes a POWER_ON reset when this occurs
RESET_REASON_PIN_RESET	Set when a reset is triggered by the hardware pin on the board.
RESET_REASON_BROWN_OUT	Triggered when the voltage drops below the low voltage detect (LVD) threshold; the system is held in a reset until the voltage rises above the threshold.
RESET_REASON_SOFTWARE	Set during software reset, typically triggered by writing the SYSRESETREQ bit in the Application Interrupt and Reset Control register.
RESET_REASON_WATCHDOG	Set when a running watchdog timer fails to be refreshed.
RESET_REASON_LOCKUP	Set when the core is locked because of an unrecoverable exception.
RESET_REASON_WAKE_LOW_POWER	Set when waking from deep sleep mode.
RESET_REASON_ACCESS_ERROR	Umbrella value that encompasses any access related reset.
RESET_REASON_BOOT_ERROR	Umbrella value that encompasses any boot related reset.
RESET_REASON_MULTIPLE	Set if multiple reset reasons are set within the board. Occurs when the reset reason registers aren't cleared between resets
RESET_REASON_PLATFORM	Platform specific reset reason not captured in this enum.
RESET_REASON_UNKNOWN	Unknown or unreadable reset reason.

Definition at line 76 of file reset_reason_api.h.

Function Documentation

void hal_reset_reason_clear ( void )

Clear the reset reason from registers.

Reset the value of the reset status registers. The reset reason persists between system resets on certain platforms, so the registers should be cleared before the system resets. Failing to do so may make it difficult to determine the cause of any subsequent system resets.

reset_reason_t hal_reset_reason_get ( void )

Fetch the reset reason for the last system reset.

This function must return the contents of the system reset reason registers cast to an appropriate platform independent reset reason. If multiple reset reasons are set, this function should return RESET_REASON_MULTIPLE. If the reset reason does not match any existing platform independent value, this function should return RESET_REASON_PLATFORM. If no reset reason can be determined, this function should return RESET_REASON_UNKNOWN.

This function is not idempotent; there is no guarantee the system reset reason will not be cleared between calls to this function altering the return value between calls.

Note: Some platforms contain reset reason registers that persist through system resets. If the registers haven't been cleared before calling this function, multiple reasons may be set within the registers. If multiple reset reasons are detected, this function returns RESET_REASON_MULTIPLE.

Returns: enum containing the last reset reason for the board.

uint32_t hal_reset_reason_get_raw ( void )

Fetch the raw platform specific reset reason register value.

This function must return the raw contents of the system reset reason registers cast to a uint32_t value. If the platform contains reset reasons that span multiple registers/addresses, the value should be concatenated into the return type.