Ultra-Low-Power (ULP) Timer Debugging and Error Handling#

The Ultra-Low-Power (ULP) Timer on the SiWx917 is a critical peripheral for energy-efficient applications.
Accurate configuration and systematic debugging ensure optimal timing precision, minimal power consumption, and reliable performance.

This section outlines practical debugging procedures, validation setups, and standardized error-code handling for diagnosing and maintaining ULP Timer functionality.

Debugging the ULP Timer#

Debugging the ULP Timer requires validating hardware setup, verifying firmware configuration, and using development tools such as oscilloscopes, logic analyzers, and Simplicity Studio.

The following sections provide a structured approach for troubleshooting and analysis.

1. Visual Inspection and Connection Checklist#

Before running tests, perform a preliminary inspection to confirm proper configuration and hardware setup.

• Verify that the ULP Timer peripheral is enabled in the project configuration (.slcp).

• Ensure the selected clock source remains active in the target power state (PS4, PS2, or PS1).

• Confirm that match value calculations align with desired timing intervals.

• Register and enable interrupt handlers correctly in the firmware.

• Configure general-purpose input/output (GPIO) pins for debugging (for example, toggling GPIOs in callbacks for visual timing validation).

Tip: A quick hardware and configuration check resolves most common timer initialization or wake-up issues.

2. Timer Verification Using SiWx917 Development Kits#

When using a SiWx917 development kit, follow these steps to validate ULP Timer functionality:

1. Connect an oscilloscope or logic analyzer to the GPIO pins used for ULP Timer verification.

2. Verify stable power supply and proper board grounding.

3. Configure the ULP Timer parameters (clock source, mode, and match value).

4. Add a GPIO toggle in the timer callback for a visible indication of interrupt execution.

5. Flash the project firmware using Simplicity Studio.

6. Observe the timing and power behavior through hardware tools.

Figure: ULP Timer debugging and measurement setup using a SiWx917 development kit.

Note: Use Simplicity Studio’s Energy Profiler to monitor real-time power usage while capturing GPIO toggles on the logic analyzer.

3. Using a Logic Analyzer for Timing Validation#

A logic analyzer provides high-resolution visibility into timer performance and interrupt execution.

Setup Steps:

• Connect probes to the GPIO pins toggled within timer callbacks.

• Set appropriate voltage thresholds and sampling rates.

• Capture intervals and validate event accuracy during ULP Timer operation.

• Ensure the analyzer’s ground reference is tied to the board ground.

Use the Logic Analyzer to Measure:

• Timer period and interval accuracy.

• Interrupt latency and timing jitter.

• Callback execution duration.

• Timer start/stop synchronization.

Tip: Compare measured intervals with expected match values to verify timer precision across power states.

4. Simplicity Studio Debugging and Power Profiling#

Simplicity Studio can be combined with external analysis tools for comprehensive ULP Timer debugging.

1. Open Simplicity Studio and switch to the Debug perspective.

2. Flash the ULP Timer test firmware to the SiWx917 board.

3. Attach the logic analyzer to designated GPIO debug pins.

4. Set breakpoints in the code for event correlation with captured analyzer signals.

5. Use the Energy Profiler tool to monitor current draw during timer operation.

6. Observe ULP Timer behavior across power states (PS4, PS2, PS1) for continuity and stability.

Note: A consistent wake-up interval and stable current trace confirm that the ULP Timer and power manager are configured correctly.

Error Code Handling#

The SiWx917 ULP Timer driver returns standardized status codes that indicate the success or failure of operations.
These codes help developers identify configuration errors, timing inconsistencies, or callback misbehavior.

Tip: Always check the API return value after each ULP Timer function call to ensure successful execution.

Resetting the ULP Timer Peripheral#

If the ULP Timer enters an undefined or error state, often due to clock changes, power-state transitions, or invalid configurations, perform a reset sequence. Deinitialize and reinitialize the peripheral to restore normal operation.

sl_si91x_ulp_timer_deinit();
sl_si91x_ulp_timer_init();