Power Manager Debugging and Error Handling#

This section provides guidance on troubleshooting, interpreting error codes, and applying best practices for effective power management in Silicon Labs applications. It also covers considerations for power state transitions, peripheral dependencies, and measuring power consumption.

Common Debugging Tips#

When debugging applications, use systematic checks to identify issues quickly. Refer to the official troubleshooting resource for detailed steps: WiSeConnect Debugging Guide.

If a power transition is not working, check the following:

Verify the domain dependency tree.
Confirm peripheral requirements.
Review power state constraints.

Error Code Handling#

Error code handling is essential for building resilient applications. This section explains how the Power Manager Service communicates results using standardized return values.

The Power Manager Service uses Silicon Labs status codes (sl_status_t) to indicate the result of an operation. These codes provide detailed diagnostic information and support robust error recovery across the power management system.

Understanding Error Codes#

All Power Manager APIs return error codes that indicate success or failure.
Each code has a unique hexadecimal value for programmatic checks.
Codes are grouped by category, such as success, state errors, parameter errors, or resource issues.
Applications should always check return values and implement appropriate recovery strategies.

Complete Error Code Reference#


Error Code	Value	Category	Description	Specific Power Manager Context	Recovery Action
SL_STATUS_OK	0x0000	Success	Operation completed successfully	API call executed without errors, power state transition completed, configuration applied successfully	Continue normal operation
SL_STATUS_FAIL	0x0001	General	General failure from underlying system	Hardware abstraction layer failure, ROM API error, clock configuration failure	Check system state, verify hardware configuration, retry after delay
SL_STATUS_INVALID_STATE	0x0002	State Error	Invalid power state for requested operation	Sleep request from PS0/PS1, conflicting PS1/Standby requests, transition not allowed in current state	Check current power state, remove conflicting requirements, ensure valid transition path
SL_STATUS_NOT_READY	0x0003	State Error	System not ready for operation	Hardware initialization incomplete, clocks not stabilized	Wait for system stabilization, check initialization sequence
SL_STATUS_BUSY	0x0004	State Error	System busy, operation cannot proceed	`app_is_ok_to_sleep()` returned false, Wi-Fi transmission in progress, peripheral operations active	Wait for idle conditions, check blocking peripherals, retry after delay
SL_STATUS_IN_PROGRESS	0x0005	State Error	Operation already in progress	Power-state transition ongoing, configuration change in process	Wait for completion, avoid concurrent operations
SL_STATUS_TIMEOUT	0x0007	State Error	Operation timed out	Power transition timeout, peripheral response timeout, clock stabilization timeout	Check hardware connections, verify system clock, increase timeout if appropriate
SL_STATUS_NOT_AVAILABLE	0x000E	State Error	Feature not available	Peripheral not present, functionality disabled, unsupported on current variant	Check hardware configuration, verify component installation, use alternative approach
SL_STATUS_NOT_SUPPORTED	0x000F	State Error	Operation not supported	Feature not implemented, unsupported power state combination	Use supported alternatives, check API documentation
SL_STATUS_NOT_INITIALIZED	0x0011	Initialization	Power Manager not initialized	API called before `sl_si91x_power_manager_init()`, service not started	Call `sl_si91x_power_manager_init()` first, ensure proper initialization sequence
SL_STATUS_ALREADY_INITIALIZED	0x0012	Initialization	Service already initialized	`sl_si91x_power_manager_init()` called multiple times	Continue normal operation, avoid duplicate initialization
SL_STATUS_ALLOCATION_FAILED	0x0019	Resource	Memory allocation failed	Insufficient heap memory, resource exhaustion	Check memory usage, free unused resources, increase heap size if needed
SL_STATUS_NO_MORE_RESOURCE	0x001A	Resource	No more resources available	Maximum callbacks registered, resource pool exhausted	Release unused resources, check resource limits
SL_STATUS_INVALID_PARAMETER	0x0021	Parameter	Invalid parameter value	Power state out of range, invalid clock scaling mode, unsupported peripheral combination	Validate parameter ranges, check enum values, verify parameter combinations
SL_STATUS_NULL_POINTER	0x0022	Parameter	Required pointer is null	Null passed for output parameter, missing configuration structure	Provide valid pointer arguments, allocate required structures
SL_STATUS_INVALID_CONFIGURATION	0x0023	Parameter	Invalid configuration	Conflicting peripheral settings, invalid RAM retention configuration	Review configuration parameters, check component dependencies
SL_STATUS_INVALID_MODE	0x0024	Parameter	Invalid mode specified	Unsupported clock scaling mode, invalid wake-up mode	Use supported mode values, check API documentation
SL_STATUS_INVALID_HANDLE	0x0025	Parameter	Invalid handle provided	Invalid event subscription handle, corrupted callback handle	Re-subscribe to events, verify handle validity
SL_STATUS_INVALID_RANGE	0x0028	Parameter	Parameter out of valid range	Counter overflow (>255), invalid RAM bank selection	Check parameter bounds, validate against supported ranges

Best Practices#

This section outlines best practices for managing power states, peripherals, sleep modes, error handling, and performance optimization.

Power State Management#

Start with PS3: Begin system initialization in PS3 mode to balance performance and power consumption.
Gradual transitions: Move through power states progressively (for example, PS3 → PS2 → PS1) to maintain system stability.
State requirements: Always add power state requirements before removing them to prevent unintended transitions.
Event handling: Subscribe to power state transition events to reconfigure peripherals when states change.

Peripheral Management#

Effective peripheral management minimizes power usage while maintaining functionality.

Power gates configuration: Enable or disable power gates based on active peripheral requirements.
RAM retention settings: Configure random access memory (RAM) retention based on memory usage during sleep.
Wake-up source selection: Choose wake-up sources (for example, general-purpose input/output [GPIO], calendar) that fit application needs.
Peripheral cleanup: Deinitialize peripherals before entering sleep modes to ensure clean state transitions.

Sleep Mode Optimization#

Sleep mode optimization reduces unnecessary power consumption.

RAM retention balance: Balance RAM retention with power savings to minimize overhead.
Peripheral shutdown: Power down unused peripherals before sleep.
Clock scaling: Apply clock scaling to reduce frequency when full performance is unnecessary.

Error Handling#

Robust error handling ensures application reliability.

Status checking: Always check return values from Power Manager API calls.
Error recovery: Implement recovery mechanisms to maintain system stability.
Graceful degradation: Design fallback strategies to handle failures without causing system crashes.

Performance Optimization#

Performance optimization reduces overhead while maintaining efficiency.

Minimize transitions: Avoid frequent or unnecessary power state transitions.
Peripheral efficiency: Keep only essential peripherals powered.
RAM usage optimization: Optimize RAM usage to reduce retention requirements during sleep.

Considerations#

This section provides considerations for managing power state requirements, handling peripheral dependencies, and measuring power consumption.

Add or Remove Power State Requirements#

The current state of the Cortex-M4 processor depends on the most recent active state. For example, if the PS4 state requirement is added and then removed, followed by adding and removing the PS3 requirement, the processor remains in the PS3 state.

In a multithreaded application:

The Power Manager maintains the highest state requested.
The processor transitions to a lower state only after all higher state requirements are removed.
If multiple requirements are added, the state changes when all requirements are removed.

Remove Peripheral Requirement#

If any peripheral is disabled in the PS4 state (for example, disabling the synchronous serial interface [SSI]), switching to the PS2 state and then back to the PS4 state powers on all peripherals again.

To disable peripherals after such transitions, call sl_si91x_power_manager_remove_peripheral_requirement().

Measuring Power Consumption#

To measure power consumption selectively:

For the Network Wireless Processor (NWP): Configure the M4 processor in PS0 without RAM retention.
For the M4 processor: Configure the NWP in deep sleep without RAM retention (DEEP_SLEEP_WITHOUT_RAM_RETENTION) when the device is not associated with an access point (AP).

Wi-Fi Dependency#

The function sl_si91x_power_manager_is_tx_command_in_progress() returns a valid status only if the Wi-Fi component is included in the system.