Embedded Systems Error Code
Systems & Devices
Embedded Systems

NMI | Non-maskable interrupt

Industry
Systems & Devices
Canonical
/systems/embedded-systems/error-codes/nmi/
Last Updated
Feb 27, 2026
Summary

A non-maskable interrupt occurred, often indicating a critical hardware or safety event.

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What This Code Means

NMI is a high-priority interrupt that typically cannot be disabled. In embedded systems it may be used for critical faults such as clock failure, watchdog early warning, brownout indications, or other safety mechanisms depending on the MCU and board design.

Where Users Usually See This Code

  • Low-level crash logs
  • Safety-critical device monitors

Why This Code Appears

  • Hardware fault or safety monitor triggered
  • Clock/power anomalies
  • Watchdog or system supervisor events

What Typically Happens Next

  • Device may reset, log an event, or enter safe mode

What This Code Is Not

  • It is not a typical application exception
  • It is not safe to guess hardware repairs based on NMI alone

Troubleshooting Checklist

  • Capture full system logs and any supervisor status flags
  • Check power stability and supply tolerances
  • Escalate to vendor diagnostics for safety-critical equipment

Notes And Edge Cases

The meaning of NMI depends heavily on how firmware maps the interrupt; consult the device’s firmware documentation.

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