Programming, Controls & SensorsModule 11 of 13

Common Mistakes and Troubleshooting

Most lost matches trace to a handful of recurring software faults: a default command that throws because it forgot its requirement, a loop overrun from chatty logging or CAN queries, a brown-out that silently kills your outputs, a CAN ID conflict, or a control loop with integral windup. This module is a field guide to those failure modes -- how to recognize each one fast, the exact tools to diagnose it (Driver Station log viewer, AdvantageScope, Glass, the scheduler watchdog), and the concrete fix. Treat it as the debugging playbook you reach for when the robot misbehaves at 11pm before a competition.

Common Mistakes and Troubleshooting is module 11 of 13 in the Programming, Controls & Sensors guide. It picks up where Worked Examples and Mini-Projects left off and hands over to Advanced Techniques and Case Studies. Its 5 lessons are about 175 minutes of the guide's ~30 hours.

5 lessons~175 min51 lessons in this guide

Start with lesson 1 All of Programming, Controls & Sensors

In this module

5 lessons

01A Systematic Debugging Workflow for FRCA repeatable triage process and the four tools every programmer should reach for: the Driver Station, the DS log viewer, AdvantageScope, and Glass.35 min read

02Command-Based Pitfalls and How to Avoid ThemThe recurring command-based mistakes -- missing requirements, reused command instances, fragile default commands, and float comparisons -- with the correct patterns.35 min read

03Loop Overruns and Watchdog WarningsWhy 'Loop time of 0.02s overrun' appears, how the scheduler watchdog points at the culprit, and how to keep the 20 ms budget.35 min read

04Power, Brown-Outs, and CAN Bus FaultsThe voltage thresholds that disable your outputs, how to spot a brown-out in the logs, and how to diagnose CAN ID conflicts and disconnects.35 min read

05Control Loop Tuning ProblemsDiagnose and fix the classic closed-loop failures: integral windup, voltage sag, actuator saturation, and missing feedforward.35 min read

Previous moduleWorked Examples and Mini-Projects

Next moduleAdvanced Techniques and Case Studies

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Articles that go deeper on this

FRC CAN Bus Explained (and How to Fix Common Problems)How the FRC CAN bus works, the daisy-chain wiring with 120-ohm termination, avoiding device ID conflicts, and fixing the most common CAN failures.8 min read

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