Understanding the Issue
Intermittent power supply issues can interrupt firmware tests, resulting in inconsistencies and failures. The Keysight DC Power Analyzer helps diagnose these issues by providing valuable telemetry data. Identifying whether the problem is due to hardware, firmware configuration, or external disturbances is crucial.
Interpreting Analyzer Data
Analyzing data from the Keysight analyzer involves getting all logs, waveforms, and patterns that might indicate power interruptions. Common indicators include:
- Voltage or Current Spikes: Sudden increases can trigger resets or unexpected behavior.
- Transient Drops: Dips in voltage can stall processors or peripherals.
- Noise Levels: High noise on lines can induce misbehavior in sensitive circuits.
You can script the data collection using Python libraries such as PyVISA to interface with the analyzer:
import pyvisa
rm = pyvisa.ResourceManager()
dc_power_analyzer = rm.open_resource('USB::1234::5678::INSTR') # Replace with your device ID
# Example command to retrieve voltage data
voltage_data = dc_power_analyzer.query(":MEAS:VOLT:DC?")
print(voltage_data)
Investigating Firmware Configuration
Ensure that the firmware's power management settings align with the hardware capabilities. This often involves debugging and reviewing configurations such as:
- Power States: Check if the transitions between various power states (sleep, idle, active) are handled properly.
- Interruptions in Power Domains: Verify that power domains aren’t inadvertently powered down by the firmware.
- Reset Handling: Ensure that resets due to power instability are logged and handled gracefully.
External Factors and Mitigation
External environmental factors can also cause intermittent power issues. Consider these aspects:
- EMI and RFI: Electromagnetic and radio frequency interferences can create noise. Use shielded cables and proper grounding.
- Power Quality: Ensure stable power supply and use UPS if necessary for sensitive tests.
- Connections: Inspect connectors for wear or corrosion which can lead to intermittent connections.
Implementing Robust Firmware
In your firmware, consider these strategies to mitigate power fluctuations:
- Debouncing Power Line Reads: Filter power line measurements to handle noise with software debounce where practical.
- Checkpointing: Use non-volatile storage to save states, so progress isn’t lost on power falter.
- Adaptive Power Management: Use dynamic scaling of resources based on real-time power availability.
Example code to handle a simple debounce:
#include <stdint.h>
#include <stdbool.h>
#define THRESHOLD 5
bool debounce_voltage(int16_t *readings, int length, int stable_threshold) {
int count = 0;
for (int i = 0; i < length; i++) {
if (readings[i] < stable_threshold) {
if (++count >= THRESHOLD) return false; // Unstable power detected
} else {
count = 0; // Reset if stable
}
}
return true; // Power stable
}
By addressing these aspects, a firmware developer can resolve intermittent power supply issues, ensuring a stable testing environment and reliable firmware performance.
