ArduPilot/ardupilot

Copter: add pre-arm check if frame can't find the output for a motor

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#7,354 opened on Dec 5, 2017

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CopterEnhancementgood first issue

Description

In Copter-3.5 (and higher) the AP_Motors library requires that the SERVOx_FUNCTION be set for each motor. Although these parameter default to good values, it's possible that a user could mess up the SERVOx_FUNCTION settings so that there are no defined outputs for some motors. We should raise a pre-arm check failure in such cases.

Contributor guide

Tech stack
cpp
Domain
security
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++AP Motors libraryArduPilot pre arm system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Start by examining how pre arm checks are implemented in ArduPilot, specifically in the Copter firmware. Look at existing pre arm checks in libraries/AP Motors/AP Motors.cpp or similar files. Understand how motors are mapped to outputs via SERVOx FUNCTION parameters. Implement a new check that iterates over motors and verifies each has a valid SERVOx FUNCTION assigned, raising a pre arm failure if not. Reference the issue for requirements.
Copter: add pre-arm check if frame can't find the output for a motor · ArduPilot/ardupilot#7354 | Good First Issue