Zero-Cross Not Detected: AC Dimmer Doesn't Respond to Commands Feb 26, 2026 0 20 TL;DR: An AC dimmer can't regulate the load if the microcontroller isn't receiving the zero-cross signal (the sine wave crossing zero). Without this signal it's impossible to calculate the TRIAC firin... Arduino ESP32 ac-dimmer troubleshooting zero-cross Read more
Wrong Library: RBDdimmer Instead of rbdimmerESP32 on ESP32 Feb 26, 2026 0 20 TL;DR: For ESP32 you need rbdimmerESP32 — not the old RBDdimmer . The old library was written for Arduino AVR: no IRAM_ATTR , no core pinning, no race condition protection. On ESP32 it causes Guru Med... Arduino ESP32 ac-dimmer troubleshooting Read more
TRIAC Overheating: AC Dimmer Runs Hot or Burns Out Feb 26, 2026 0 20 TL;DR: A TRIAC is an active device with a voltage drop of ~1.2V. At load currents above 2A it dissipates several watts as heat. Without thermal management: overheating, thermal protection triggering, ... Arduino TRIAC ac-dimmer troubleshooting Read more
ESP32-S2/C3/H2: AC Dimmer Doesn't Work on Single-Core ESP32 Feb 26, 2026 0 20 TL;DR: rbdimmerESP32 is designed for dual-core ESP32 (original and S3). ESP32-S2, C3, C6, and H2 are single-core. The library tries to isolate the dimmer task on a dedicated core — which is impossible... ESP32 ac-dimmer dimmerlink troubleshooting Read more
ESP32 + AC Dimmer: Guru Meditation Error and IRAM_ATTR — Causes and Fix Feb 26, 2026 0 19 TL;DR: If your ESP32 with an AC dimmer crashes ("Guru Meditation Error" or "Cache disabled but cached memory region accessed"), the cause is that the zero-cross ISR handler is not marked with IRAM_ATT... ESP32 IRAM_ATTR WiFi ac-dimmer troubleshooting Read more
AC TRIAC Dimmer Is Not PWM: How Phase-Cut Dimming Works Feb 26, 2026 0 19 TL;DR: analogWrite() and PWM don't work with an AC TRIAC dimmer. A TRIAC is not a resistor or a DC transistor. It regulates power using phase-cut control : it opens at a precisely calculated moment ea... Arduino ESP32 TRIAC ac-dimmer troubleshooting Read more