EMU - Energy Management Unit

Description

Energy Management Unit (EMU) Peripheral API.

This module contains functions to control the EMU peripheral of Silicon Labs 32-bit MCUs and SoCs. The EMU handles the different low energy modes in Silicon Labs microcontrollers.

Data Structures

struct EMU_EM23Init_TypeDef
EM2 and 3 initialization structure.
struct EMU_EM4Init_TypeDef
EM4 initialization structure.
struct EMU_BUPDInit_TypeDef
Backup Power Domain Initialization structure.

Functions

void EMU_EM23Init (const EMU_EM23Init_TypeDef *em23Init)
Update the EMU module with Energy Mode 2 and 3 configuration.
void EMU_EM23PresleepHook (void)
Energy mode 2/3 pre-sleep hook function.
void EMU_EM23PostsleepHook (void)
Energy mode 2/3 post-sleep hook function.
void EMU_EM4Init (const EMU_EM4Init_TypeDef *em4Init)
Update the EMU module with Energy Mode 4 configuration.
void EMU_EnterEM2 (bool restore)
Enter energy mode 2 (EM2).
void EMU_EnterEM3 (bool restore)
Enter energy mode 3 (EM3).
void EMU_Save (void)
Save the CMU HF clock select state, oscillator enable, and voltage scaling (if available) before EMU_EnterEM2() or EMU_EnterEM3() are called with the restore parameter set to false.
void EMU_Restore (void)
Restore CMU HF clock select state, oscillator enable, and voltage scaling (if available) after EMU_EnterEM2() or EMU_EnterEM3() are called with the restore parameter set to false.
void EMU_EnterEM4 (void)
Enter energy mode 4 (EM4).
void EMU_MemPwrDown (uint32_t blocks)
Power down memory block.
void EMU_RamPowerDown (uint32_t start, uint32_t end)
Power down RAM memory blocks.
void EMU_RamPowerUp (void)
Power up all available RAM memory blocks.
void EMU_UpdateOscConfig (void)
Update EMU module with CMU oscillator selection/enable status.
void EMU_BUPDInit (const EMU_BUPDInit_TypeDef *bupdInit)
Configure Backup Power Domain settings.
void EMU_BUThresholdSet ( EMU_BODMode_TypeDef mode, uint32_t value)
Configure the Backup Power Domain BOD Threshold value.
void EMU_BUThresRangeSet ( EMU_BODMode_TypeDef mode, uint32_t value)
Configure the Backup Power Domain BOD Threshold Range.
void EMU_BUStatEnSet (bool enable)
Enable backup mode status export.
void EMU_BUEnableSet (bool enable)
Enable backup mode.
void EMU_EnterEM1 (void)
Enter energy mode 1 (EM1).
void EMU_IntClear (uint32_t flags)
Clear one or more pending EMU interrupts.
void EMU_IntDisable (uint32_t flags)
Disable one or more EMU interrupts.
void EMU_IntEnable (uint32_t flags)
Enable one or more EMU interrupts.
uint32_t EMU_IntGet (void)
Get pending EMU interrupt flags.
uint32_t EMU_IntGetEnabled (void)
Get enabled and pending EMU interrupt flags.
void EMU_IntSet (uint32_t flags)
Set one or more pending EMU interrupts.
void EMU_EM4Lock (bool enable)
Enable or disable EM4 lock configuration.
void EMU_BUReady (void)
Halts until backup power functionality is ready.
void EMU_BUPinEnable (bool enable)
Disable BU_VIN support.
void EMU_Lock (void)
Lock EMU registers in order to protect them against unintended modification.
void EMU_Unlock (void)
Unlock the EMU so that writing to locked registers again is possible.
void EMU_EM2Block (void)
Block entering EM2 or higher number energy modes.
void EMU_EM2UnBlock (void)
Unblock entering EM2 or higher number energy modes.

Macros

#define EMU_EM23INIT_DEFAULT
Default initialization of EM2 and 3 configuration.
#define EMU_EM4INIT_DEFAULT
Default initialization of EM4 configuration (Series 0).
#define EMU_BUPDINIT_DEFAULT
Default Backup Power Domain configuration.

Enumerations

enum EMU_EM4Osc_TypeDef {
emuEM4Osc_ULFRCO = EMU_EM4CONF_OSC_ULFRCO,
emuEM4Osc_LFXO = EMU_EM4CONF_OSC_LFXO,
emuEM4Osc_LFRCO = EMU_EM4CONF_OSC_LFRCO
}
EM4 duty oscillator.
enum EMU_Probe_TypeDef {
emuProbe_Disable = EMU_BUCTRL_PROBE_DISABLE,
emuProbe_VDDDReg = EMU_BUCTRL_PROBE_VDDDREG,
emuProbe_BUIN = EMU_BUCTRL_PROBE_BUIN,
emuProbe_BUOUT = EMU_BUCTRL_PROBE_BUOUT
}
Backup Power Voltage Probe types.
enum EMU_Resistor_TypeDef {
emuRes_Res0 = EMU_PWRCONF_PWRRES_RES0,
emuRes_Res1 = EMU_PWRCONF_PWRRES_RES1,
emuRes_Res2 = EMU_PWRCONF_PWRRES_RES2,
emuRes_Res3 = EMU_PWRCONF_PWRRES_RES3
}
Backup Power Domain resistor selection.
enum EMU_Power_TypeDef {
emuPower_None = EMU_BUINACT_PWRCON_NONE,
emuPower_BUMain = EMU_BUINACT_PWRCON_BUMAIN,
emuPower_MainBU = EMU_BUINACT_PWRCON_MAINBU,
emuPower_NoDiode = EMU_BUINACT_PWRCON_NODIODE
}
Backup Power Domain power connection.
enum EMU_BODMode_TypeDef {
emuBODMode_Active ,
emuBODMode_Inactive
}
BOD threshold setting selector, active or inactive mode.
enum EMU_EM4State_TypeDef {
emuEM4Shutoff = 0,
emuEM4Hibernate = 1
}
EM4 modes.
enum EMU_PowerConfig_TypeDef { emuPowerConfig_DcdcToDvdd }
Power configurations.

Function Documentation

◆ EMU_EM23Init()

void EMU_EM23Init ( const EMU_EM23Init_TypeDef * em23Init )

Update the EMU module with Energy Mode 2 and 3 configuration.

Parameters
[in] em23Init Energy Mode 2 and 3 configuration structure.

◆ EMU_EM23PresleepHook()

void EMU_EM23PresleepHook ( void )

Energy mode 2/3 pre-sleep hook function.

This function is called by EMU_EnterEM2() and EMU_EnterEM3() functions just prior to execution of the WFI instruction. The function implementation does not perform anything, but it is SL_WEAK so that it can be re- implemented in application code if actions are needed.

Note
The function is primarily meant to be used in systems with EFP circuitry. (EFP = Energy Friendly Pmic (PMIC = Power Management IC)). In such systems there is a need to drive certain signals to EFP pins to notify about energy mode transitions.

◆ EMU_EM23PostsleepHook()

void EMU_EM23PostsleepHook ( void )

Energy mode 2/3 post-sleep hook function.

This function is called by EMU_EnterEM2() and EMU_EnterEM3() functions just after wakeup from the WFI instruction. The function implementation does not perform anything, but it is SL_WEAK so that it can be re- implemented in application code if actions are needed.

Note
The function is primarily meant to be used in systems with EFP circuitry. (EFP = Energy Friendly Pmic (PMIC = Power Management IC)). In such systems there is a need to drive certain signals to EFP pins to notify about energy mode transitions.

◆ EMU_EM4Init()

void EMU_EM4Init ( const EMU_EM4Init_TypeDef * em4Init )

Update the EMU module with Energy Mode 4 configuration.

Parameters
[in] em4Init Energy Mode 4 configuration structure.

◆ EMU_EnterEM2()

void EMU_EnterEM2 ( bool restore )

Enter energy mode 2 (EM2).

When entering EM2, high-frequency clocks are disabled, i.e., HFXO, HFRCO and AUXHFRCO (for AUXHFRCO, see exception note below). When re-entering EM0, HFRCO is re-enabled and the core will be clocked by the configured HFRCO band. This ensures a quick wakeup from EM2.

However, prior to entering EM2, the core may have been using another oscillator than HFRCO. The restore parameter gives the user the option to restore all HF oscillators according to state prior to entering EM2, as well as the clock used to clock the core. This restore procedure is handled by SW. However, since handled by SW, it will not be restored before completing the interrupt function(s) waking up the core!

Note
If restoring core clock to use the HFXO oscillator, which has been disabled during EM2 mode, this function will stall until the oscillator has stabilized. Stalling time can be reduced by adding interrupt support detecting stable oscillator, and an asynchronous switch to the original oscillator. See CMU documentation. Such a feature is however outside the scope of the implementation in this function.
If ERRATA_FIX_EMU_E110_ENABLE is active, the core's SLEEPONEXIT feature can not be used.
If HFXO is re-enabled by this function, and NOT used to clock the core, this function will not wait for HFXO to stabilize. This must be considered by the application if trying to use features relying on that oscillator upon return.
If a debugger is attached, the AUXHFRCO will not be disabled if enabled upon entering EM2. It will thus remain enabled when returning to EM0 regardless of the restore parameter.
If HFXO autostart and select is enabled by using CMU_HFXOAutostartEnable(), the automatic starting and selecting of the core clocks will be done, regardless of the restore parameter, when waking up on the wakeup sources corresponding to the autostart and select setting.
If voltage scaling is supported, the restore parameter is true and the EM0 voltage scaling level is set higher than the EM2 level, then the EM0 level is also restored.
On Series 2 Config 2 devices (EFRxG22), this function will also relock the DPLL if the DPLL is used and restore is true.

Note that the hardware will automatically update the HFRCO frequency in the case where voltage scaling is used in EM2/EM3 and not in EM0/EM1. When the restore argument to this function is true then software will restore the original HFRCO frequency after EM2/EM3 wake up. If the restore argument is false then the HFRCO frequency is 19 MHz when coming out of EM2/EM3 and all wait states are at a safe value.

Parameters
[in] restore
  • true - save and restore oscillators, clocks and voltage scaling, see function details.
  • false - do not save and restore oscillators and clocks, see function details.
The restore option should only be used if all clock control is done via the CMU API.

◆ EMU_EnterEM3()

void EMU_EnterEM3 ( bool restore )

Enter energy mode 3 (EM3).

When entering EM3, the high-frequency clocks are disabled by hardware, i.e., HFXO, HFRCO, and AUXHFRCO (for AUXHFRCO, see exception note below). In addition, the low-frequency clocks, i.e., LFXO and LFRCO are disabled by software. When re-entering EM0, HFRCO is re-enabled and the core will be clocked by the configured HFRCO band. This ensures a quick wakeup from EM3.

However, prior to entering EM3, the core may have been using an oscillator other than HFRCO. The restore parameter gives the user the option to restore all HF/LF oscillators according to state prior to entering EM3, as well as the clock used to clock the core. This restore procedure is handled by software. However, since it is handled by software, it will not be restored before completing the interrupt function(s) waking up the core!

Note
If restoring core clock to use an oscillator other than HFRCO, this function will stall until the oscillator has stabilized. Stalling time can be reduced by adding interrupt support detecting stable oscillator, and an asynchronous switch to the original oscillator. See CMU documentation. This feature is, however, outside the scope of the implementation in this function.
If ERRATA_FIX_EMU_E110_ENABLE is active, the core's SLEEPONEXIT feature can't be used.
If HFXO/LFXO/LFRCO are re-enabled by this function, and NOT used to clock the core, this function will not wait for those oscillators to stabilize. This must be considered by the application if trying to use features relying on those oscillators upon return.
If a debugger is attached, the AUXHFRCO will not be disabled if enabled upon entering EM3. It will, therefore, remain enabled when returning to EM0 regardless of the restore parameter.
If voltage scaling is supported, the restore parameter is true and the EM0 voltage scaling level is set higher than the EM3 level, then the EM0 level is also restored.
On Series 2 Config 2 devices (EFRxG22), this function will also relock the DPLL if the DPLL is used and restore is true.
Parameters
[in] restore
  • true - save and restore oscillators, clocks and voltage scaling, see function details.
  • false - do not save and restore oscillators and clocks, see function details.
The restore option should only be used if all clock control is done via the CMU API.

◆ EMU_Save()

void EMU_Save ( void )

Save the CMU HF clock select state, oscillator enable, and voltage scaling (if available) before EMU_EnterEM2() or EMU_EnterEM3() are called with the restore parameter set to false.

Calling this function is equivalent to calling EMU_EnterEM2() or EMU_EnterEM3() with the restore parameter set to true, but it allows the state to be saved without going to sleep. The state can be restored manually by calling EMU_Restore() .

◆ EMU_Restore()

void EMU_Restore ( void )

Restore CMU HF clock select state, oscillator enable, and voltage scaling (if available) after