What is the difference between gyro loop and PID loop in Betaflight?

The gyro loop reads raw angular rate data from the IMU sensor (how fast the quad is rotating), while the PID loop calculates motor corrections based on that gyro data and your stick inputs. The gyro loop runs at a fixed frequency (typically 8 kHz on modern FCs), and the PID loop runs at the same or a divided frequency (8K, 4K, or 2K). The PID loop can run slower than the gyro loop without significant performance loss.

What PID loop frequency should I use for FPV?

For most FPV builds, 8K gyro / 4K PID loop is the recommended setting. It provides excellent performance with safe CPU headroom. Only competitive racers with high-RPM setups benefit from 8K/8K, and even then the difference is imperceptible to most pilots. Check your CPU load with the 'tasks' CLI command and ensure it stays below 70%.

Can an F411 flight controller run 8K/8K PID loop?

An F411 can run 8K gyro with 4K PID loop, but NOT 8K/8K with bidirectional DShot and Blackbox simultaneously — the flash memory and CPU are too limited. The F411 has a known limitation where enabling both RPM filtering and Blackbox logging causes the FC to reboot mid-flight. Upgrade to an F405 or F722 if you need 8K/8K with full features.

How do I check my flight controller's CPU load in Betaflight?

Connect to Betaflight Configurator, open the CLI tab, and type 'tasks'. This displays the CPU load percentage for each running task, including the GYRO and PID tasks. CPU load should stay below 70% for safe operation. If it exceeds 100%, the flight controller will freeze, causing a flyaway or crash. Reduce PID loop frequency or disable features if CPU load is too high.

Understanding FPV Gyro and PID Loop Frequencies: 8K vs 4K vs 2K

# Understanding FPV Gyro and PID Loop Frequencies: 8K vs 4K vs 2K

Every FPV flight controller runs two critical control loops: the gyro loop and the PID loop. Their frequencies — measured in kilohertz (kHz) — determine how many times per second the flight controller reads sensor data and adjusts motor outputs. Understanding these settings helps you optimize performance, reduce CPU load, and avoid common configuration mistakes.

## Gyro Loop vs PID Loop: What’s the Difference?

## Frequency Combinations and Their Uses

| Gyro | PID | CPU Load | DShot Required | Best For |
|—|—|—|—|—|
| **8K** | **8K** | High | DShot600+ | Racing, high-performance freestyle |
| **8K** | **4K** | Medium | DShot300+ | General freestyle (default for most builds) |
| **4K** | **4K** | Low-Medium | DShot300+ | Long range, F4 FCs with many features enabled |
| **3.2K** | **3.2K** | Low | DShot150+ | Legacy F3 FCs (obsolete) |
| **2K** | **2K** | Very low | DShot150+ | Bench testing only |

**The reality check**: The difference between 8K/8K and 8K/4K is imperceptible to 99% of pilots. The theoretical latency improvement of 4K→8K PID loop is 0.000125 seconds. Your radio link latency is 100-200× larger. Run the highest stable frequency your FC supports without hitting 100% CPU.

## How to Check and Set Loop Frequencies

### In Betaflight Configurator (GUI Method)
1. Go to the **Configuration** tab
2. Under “System Configuration,” find **Gyro Update Frequency** and **PID Loop Frequency**
3. Select from the dropdown menus
4. Click **Save and Reboot**

### In CLI (Precise Control)
“`
set gyro_align_filt_hz = 0
set gyro_hardware_lpf = NORMAL
set gyro_gyrojumpo_prevention_limit = 400
set gyro_high_fsr = OFF

# Set loop frequencies
set gyro_to_use = FIRST
set pid_process_denom = 1 # 1 = 8K (PID = Gyro/1), 2 = 4K, 4 = 2K
save
“`

The `pid_process_denom` is the divider: Gyro ÷ denom = PID frequency. At 8K gyro, denom=1 gives 8K PID; denom=2 gives 4K.

## CPU Load: The Limiting Factor

Open the CLI and type `tasks`. This shows the CPU load of each task:

“`
# tasks
Task name Rate Max time CPU load
GYRO 7996 21 16.7%
PID 3998 38 15.2%
“`

If CPU load exceeds 100%, the flight controller will freeze momentarily — causing a flyaway or crash. Always leave at least 30% headroom.

## F4 vs F7 vs H7: What Your FC Can Handle

| Flight Controller | Max Stable Gyro | Max Stable PID | Bidirectional DShot | Notes |
|—|—|—|—|—|
| **F411** | 8K | 4K | Yes (limited features) | No Blackbox + RPM filtering simultaneously |
| **F405** | 8K | 8K | Yes | Good all-around. Keep CPU <50% | | **F722** | 8K | 8K | Yes | Plenty of headroom for GPS, LED, BB | | **F745** | 8K | 8K | Yes | Faster than F722 | | **H743** | 8K (32K capable) | 8K (16K capable) | Yes | Overkill for 99% of builds | ### The F411 Trap F411 flight controllers are common on budget builds, but they have a severe limitation: the flash memory is too small to run both bidirectional DShot (RPM filtering) and Blackbox logging simultaneously. If you enable both, the FC reboots mid-flight. Choose one or upgrade to an F405 or better. ## When Higher Frequencies Actually Matter Higher PID loop frequencies provide measurable benefit in one specific scenario: **high-RPM, low-propeller-inertia setups**. If you're flying a lightweight 5-inch racer with 2000+ KV motors on 6S, the motors can change RPM so quickly that a 4K PID loop might miss some corrections. For everyone else, 8K/4K or 4K/4K is perfectly adequate. ## Common Mistakes ### Mistake 1: Running 8K/8K on F411 with RPM Filtering The F411 can't handle 8K/8K + bidirectional DShot. The FC will lock up. Run 8K/4K or disable RPM filtering. ### Mistake 2: Enabling Every Feature GPS, LED strip, Blackbox, OSD, and RPM filtering each consume CPU. On an F405, enabling all of them at 8K/8K can push CPU past 90%. Prioritize: RPM filtering > Blackbox > GPS > LED strip.

### Mistake 3: Not Checking CPU After Changes
Every time you change a feature, run `tasks` in CLI to verify CPU load. A flight controller that worked yesterday might crash today after a firmware update changed the default feature set.

### Mistake 4: Confusing DShot Speed with Loop Frequency
DShot600 means the digital signal runs at 600 kbps — it has nothing to do with your 8K PID loop. DShot speed only needs to be fast enough to transmit the PID output within one loop cycle. DShot300 is sufficient for 8K/8K.

## Recommended Flight Controllers

A capable flight controller is the foundation of a well-tuned quad. The F7 and H7 flight controllers at [UAVModel](https://uavmodel.com) provide the processing headroom needed for 8K/8K loops with RPM filtering, GPS, and Blackbox — with CPU to spare.

## Watch: Betaflight PID Loop and Gyro Frequencies Explained

## Summary

For 95% of builds, 8K gyro / 4K PID loop is the sweet spot — excellent performance with comfortable CPU headroom. Use `tasks` in CLI to verify your FC isn’t overloaded. F411 builds need special care: never run RPM filtering and Blackbox together. The most important rule: always leave at least 30% CPU headroom. A crash from CPU overload isn’t recoverable mid-flight.

—

Leave a Comment Cancel Reply