USB-OTG Cables & Power

The "Host" Dilemma

USB communication requires one device to be the Host (Master) and one to be the Device (Slave).

• Standard: The Android phone acts as the Host.
• Implication: The Host provides 5V power to the Slave.

Power Architecture

1. Phone-Powered (Standard OTG)

• Setup: OTG adapter on phone side.
• Flow: Phone Battery -> USB Cable -> Flight Controller.
• Risk: The phone is powering the FC's CPU, receiver, and GPS. This drains the phone battery rapidly.
• Safety: Ensure your FC's BEC (Battery Eliminator Circuit) is powerful enough to handle the voltage drop if the phone stops supplying power (unlikely in this direction, but voltage contention can occur).

2. Drone-Powered (Charge-While-Use)

This is the ideal setup for long endurance.

• Setup: You need a "Y-Cable" or a specific OTG hub that supports Power Injection.
• Flow: Drone LiPo -> 5V BEC -> USB Cable -> Phone.
• Requirement: The phone must support "Charge and Data" simultaneously. Most modern USB-C phones do, but older Micro-USB phones often do not.

Cable Hygiene

• Length: Keep it short (10-15cm). Long loops induce magnetic interference.
• Shielding: Use high-quality shielded data cables. Unshielded USB traffic generates noise at 480MHz, which can generate harmonics that interfere with 900MHz telemetry or 433MHz RC links.
• Ferrites: A clip-on ferrite bead near the FC connector can reduce RF noise injection into the autopilot.