Reduce CPU overhead by rate-limiting updateArmingStatus() to 200 Hz

[sensei-hacker]

User description

Summary

Rate-limit updateArmingStatus() from every PID loop iteration (2000 Hz) to 200 Hz, reducing CPU overhead by 10-13%.

Changes

• Added rate divider to call updateArmingStatus() every 10th PID loop iteration
• No functional change to arming safety checks, LED updates, or status monitoring

Rationale

The updateArmingStatus() function performs 20+ safety checks (GPS fix quality, battery voltage, sensor health, failsafe status, LED indicators) that don't require millisecond-level updates:

• GPS updates at 5-10 Hz
• Battery voltage changes gradually
• Human reaction time is ~200ms
• 200 Hz (5ms response) is well within safety margins

Testing

Tested on AT32F435 hardware (BLUEBERRYF435WING):

• Before: 187 µs average PID loop time
• After: 163 µs average PID loop time
• Improvement: 24 µs (12.8%)

All arming safety checks, LED indicators, and mode switching remain fully functional.

Impact

• Benefits all INAV targets (F4, F7, H7, AT32)
• Frees CPU headroom for navigation features
• No settings changes required
• No breaking changes

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PR Type

Enhancement

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Description

• Rate-limit updateArmingStatus() from 2000 Hz to 200 Hz

• Reduces CPU overhead by 10-13% on PID loop execution

• Maintains all safety checks and functional behavior

• No configuration changes or breaking changes required

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Diagram Walkthrough

flowchart LR
  A["PID Loop 2000 Hz"] -- "every 10th iteration" --> B["updateArmingStatus 200 Hz"]
  B --> C["Safety Checks"]
  B --> D["LED Updates"]
  B --> E["Status Monitoring"]
  C --> F["No Functional Impact"]
  D --> F
  E --> F

Loading

File Walkthrough

	Relevant files
Enhancement	fc_core.c Implement rate divider for updateArmingStatus() function  src/main/fc/fc_core.c Added static rate divider counter to skip updateArmingStatus() calls Executes updateArmingStatus() every 10th PID loop iteration instead of every iteration Reduces function call frequency from 2000 Hz to 200 Hz Added explanatory comment documenting the 200 Hz rate-limiting +6/-1

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[qodo-code-review]

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[qodo-code-review]

Suggestion: Replace the iteration-based counter with a time-based check using currentTimeUs to ensure updateArmingStatus() runs at a consistent 200 Hz. [general, importance: 7]

Suggested change

	static uint8_t armingStatusDivider = 0;
	if (++armingStatusDivider >= 10) {
	armingStatusDivider = 0;
	updateArmingStatus();
	}
	static timeUs_t lastArmingStatusTimeUs = 0;
	if ((int32_t)(currentTimeUs - lastArmingStatusTimeUs) >= 5000) {
	lastArmingStatusTimeUs = currentTimeUs;
	updateArmingStatus();
	}