arm-fc-physical

Arm a physical flight controller via MSP and download blackbox logs for analysis

When to Use This Skill

• Generate blackbox logs from physical FC for debugging
• Test firmware behavior without actual flight
• Capture sensor data for analysis
• Validate blackbox logging is working correctly

Quick Start

1. Configure FC (One-Time Setup)

# Check FC status
~/.claude/skills/flash-firmware-dfu/fc-cli.py status /dev/ttyACM0

# Configure MSP receiver and arming
cd claude/developer/scripts/testing/inav/gps
python3 configure_fc_for_msp_arming.py /dev/ttyACM0
python3 configure_fc_blackbox.py /dev/ttyACM0

# Calibrate accelerometer via INAV Configurator (if needed)

2. Generate Blackbox Log

SAFETY: Remove propellers before arming!

cd claude/developer/scripts/testing/inav/gps

# Arm for 30 seconds (default)
python3 continuous_msp_rc_sender.py /dev/ttyACM0

# Arm for custom duration
python3 continuous_msp_rc_sender.py /dev/ttyACM0 --duration 60

3. Download Log

cd claude/developer/scripts/testing/inav/gps

# Download to default filename
python3 download_blackbox_from_fc.py /dev/ttyACM0

# Download to specific file
python3 download_blackbox_from_fc.py /dev/ttyACM0 test_log.TXT

4. Decode and Analyze

# Decode log to CSV
blackbox_decode test_log.TXT

# Creates: test_log.01.csv, test_log.01.gps.csv
# View data
head -50 test_log.01.csv

Prerequisites

Hardware:

• Flight controller with USB connection
• FC appears as /dev/ttyACM0 (or similar)
• Propellers removed!

Software:

pip3 install pyserial
pip3 install git+https://github.com/xznhj8129/mspapi2

FC Configuration:

1. Accelerometer calibrated (via Configurator)
2. MSP receiver configured (rx_spi_protocol = MSP)
3. ARM mode on AUX1 (range 1700-2100)
4. Blackbox enabled (blackbox_device = SPIFLASH)

Common Issues

FC Won't Arm

Check arming flags:

~/.claude/skills/flash-firmware-dfu/fc-cli.py status /dev/ttyACM0

Common blockers:

• ACC - Calibrate accelerometer via Configurator
• CAL - Wait 5+ seconds after boot
• ANGLE - Level FC or disable small_angle check
• SETTINGFAIL - Fix RX settings with configure script

No Blackbox Data (0 bytes)

1. HITL mode was used - Use continuous_msp_rc_sender.py instead
2. FC not armed - Check arming flags
3. Blackbox not configured - Run configure_fc_blackbox.py
4. Flash full - Erase via Configurator

Serial Port Permission Denied

sudo usermod -a -G dialout $USER
# Log out and back in

Key Scripts

All located in: claude/developer/scripts/testing/inav/gps/

• continuous_msp_rc_sender.py - Arm FC and send RC frames
• download_blackbox_from_fc.py - Download log via MSP
• configure_fc_for_msp_arming.py - Configure MSP receiver
• configure_fc_blackbox.py - Configure blackbox settings

Technical Details

RC Frame Rate: 50 Hz (matches CRSF standard) Download Speed: ~2.5 KB/s (~20s for 50KB log) MSP Commands Used:

• MSP_SET_RAW_RC (200) - Send RC channels
• MSP_DATAFLASH_SUMMARY (70) - Query flash status
• MSP_DATAFLASH_READ (71) - Download data

RC Channel Mapping (AETR):

• Channel 3: Throttle (1000=low, 1600=mid)
• Channel 5: AUX1 ARM (1000=disarm, 1800=arm)

See Also

• Detailed Guide: .claude/skills/arm-fc-physical/REFERENCE.md
• Flash Firmware: /flash-firmware-dfu
• Build Firmware: /build-inav-target
• Arm SITL: /sitl-arm
• MSP Protocol: /msp-protocol