---
name: esp32-35caf2de9f80
description: Avoid common ESP32 mistakes — GPIO conflicts, WiFi+ADC2 trap, deep sleep gotchas, and FreeRTOS pitfalls.
metadata: {"clawdbot":{"emoji":"📟","os":["linux","darwin","win32"]}}
---

## GPIO Restrictions
- Strapping pins boot behavior — GPIO0, GPIO2, GPIO12, GPIO15 affect boot mode
- GPIO6-11 connected to flash — don't use, crashes immediately
- GPIO34-39 input only — no output, no pullup/pulldown
- ADC2 unusable with WiFi active — use ADC1 (GPIOs 32-39) when WiFi enabled

## Deep Sleep
- Only RTC GPIOs for wakeup — GPIO0, 2, 4, 12-15, 25-27, 32-39
- `RTC_DATA_ATTR` for persistent variables — regular RAM lost in deep sleep
- `esp_sleep_enable_ext0_wakeup()` for single pin — `ext1` for multiple pins
- WiFi reconnect takes 1-3 seconds after wake — plan for this delay

## WiFi Gotchas
- Call `WiFi.mode()` before `WiFi.begin()` — mode affects behavior
- `WiFi.setAutoReconnect(true)` doesn't always work — implement reconnect in loop
- Event-driven with `WiFi.onEvent()` more reliable — don't poll `WiFi.status()`
- Static IP faster than DHCP — saves 2-5 seconds on connect

## FreeRTOS
- Default stack too small for printf/WiFi — use 4096+ for complex tasks
- Task watchdog triggers at 5s default — call `vTaskDelay()` or feed watchdog
- `xTaskCreatePinnedToCore()` for core affinity — WiFi on core 0, your code on core 1
- `delay()` yields to scheduler — `vTaskDelay(pdMS_TO_TICKS(ms))` in tasks

## Memory
- Heap fragments over time — preallocate buffers, avoid repeated malloc/free
- `ESP.getFreeHeap()` for monitoring — log periodically in long-running apps
- PSRAM available on some boards — `heap_caps_malloc(size, MALLOC_CAP_SPIRAM)`
- String concatenation fragments heap — use `reserve()` or char arrays

## Peripherals
- No native `analogWrite()` — use LEDC: `ledcSetup()`, `ledcAttachPin()`, `ledcWrite()`
- I2C needs external pullups usually — internal pullups too weak for fast speeds
- SPI CS pin must be managed — `SPI.begin()` doesn't auto-configure
- UART0 is Serial/USB — use UART1/2 for external devices

## OTA Updates
- Needs two OTA partitions — default partition scheme may have only one
- Check `ESP.getFreeSketchSpace()` — OTA fails silently if not enough space
- `ArduinoOTA` blocks during update — handle in loop, not in time-critical code

## Power
- Brown-out detector resets at ~2.4V — `esp_brownout_disable()` if using battery
- WiFi TX uses 300mA peaks — power supply must handle spikes
- Deep sleep ~10µA — but RTC peripherals add more if enabled


---
Source attribution: modbender
Original project: https://github.com/modbender/skill-library-mcp/blob/d9c8fe903b5b4e82237dbe8d0df8567783022e18/data/esp32/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2025 skill-library-mcp contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: modbender
Original project: https://github.com/modbender/skill-library-mcp/blob/d9c8fe903b5b4e82237dbe8d0df8567783022e18/data/esp32/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering
Roles: Backend Developer, DevOps / SRE, Embedded / IoT Developer
Specialties: Backend
Tools: Esp32
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 93f4049ad6b7c02bab17880993458965ea737c64c52fe02158f01a5d4c4817f8