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ESP32 and ESP8266 Examples

Examples for ESP32 DevKit V1, ESP32-S3-DevKitC-1, ESP8266 NodeMCU, and Wemos D1 Mini boards.

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All ESP boards use a dual-sided header layout. Physical pin numbers are used in board_pin (not GPIO numbers). Use pinviz list to see each board's full pinout.

Pin Reference

Board I2C SPI Power
ESP32 DevKit V1 GPIO21 (SDA), GPIO22 (SCL) GPIO18 (SCK), GPIO19 (MISO), GPIO23 (MOSI), GPIO5 (CS) 3V3, 5V, GND (multiple)
ESP8266 NodeMCU GPIO4 (SDA), GPIO5 (SCL) GPIO14 (SCK), GPIO12 (MISO), GPIO13 (MOSI), GPIO15 (CS) 3V3, GND (4×)
Wemos D1 Mini GPIO4 (SDA), GPIO5 (SCL) GPIO14 (SCK), GPIO12 (MISO), GPIO13 (MOSI), GPIO15 (CS) 3V3, 5V, GND

ESP32 Weather Station

BME280 environmental sensor and SSD1306 OLED display sharing the I2C bus on ESP32 DevKit V1. Also available as the built-in esp32_weather example.

Configuration: examples/esp32_weather_station.yaml

title: "ESP32 Weather Station"
board: "esp32_devkit_v1"

devices:
  - type: "bme280"
    name: "BME280 Environmental Sensor"
  - type: "ssd1306"
    name: "SSD1306 OLED Display"

connections:
  # BME280 Sensor
  - board_pin: 1   # 3V3
    device: "BME280 Environmental Sensor"
    device_pin: "VCC"
  - board_pin: 3   # GND
    device: "BME280 Environmental Sensor"
    device_pin: "GND"
  - board_pin: 21  # GPIO21 (I2C SDA)
    device: "BME280 Environmental Sensor"
    device_pin: "SDA"
  - board_pin: 27  # GPIO22 (I2C SCL)
    device: "BME280 Environmental Sensor"
    device_pin: "SCL"

  # SSD1306 OLED Display (shares I2C bus)
  - board_pin: 1   # 3V3 (shared)
    device: "SSD1306 OLED Display"
    device_pin: "VCC"
  - board_pin: 4   # GND
    device: "SSD1306 OLED Display"
    device_pin: "GND"
  - board_pin: 21  # GPIO21 (I2C SDA, shared)
    device: "SSD1306 OLED Display"
    device_pin: "SDA"
  - board_pin: 27  # GPIO22 (I2C SCL, shared)
    device: "SSD1306 OLED Display"
    device_pin: "SCL"

show_legend: true

Generate:

pinviz example esp32_weather -o esp32_weather.svg
# Or from YAML file
pinviz render examples/esp32_weather_station.yaml -o esp32_weather.svg

Result:

ESP32 Weather Station

Board aliases: esp32_devkit_v1, esp32, esp32_devkit

ESP32 DevKit V1 - I2C Sensor

Single BME280 sensor on ESP32 DevKit V1.

Result:

ESP32 I2C Sensor

Key Features: I2C connection on GPIO21 (SDA) and GPIO22 (SCL), 3.3V power.

ESP32-S3 CAN (TWAI) via SN65HVD230

SN65HVD230 CAN transceiver on the ESP32-S3-DevKitC-1 (44-pin dual-sided). The ESP32-S3's TWAI controller drives the bus through the transceiver: CAN_TX (GPIO43) → CTX driver input, CAN_RX (GPIO44) ← CRX receiver output.

Configuration: examples/esp32_s3_can_transceiver.yaml

title: ESP32-S3 CAN (TWAI) via SN65HVD230
board: esp32_s3_devkitc1
theme: light

devices:
  - type: sn65hvd230
    name: SN65HVD230 CAN Transceiver

connections:
  # 3V3 rail  (physical pin 1  -> GPIO/rail 3V3)
  - board_pin: 1
    device: SN65HVD230 CAN Transceiver
    device_pin: "3V3"
    color: red
  # GND       (physical pin 2)
  - board_pin: 2
    device: SN65HVD230 CAN Transceiver
    device_pin: "GND"
    color: black
  # CAN_TX = GPIO43 (physical pin 4) -> transceiver CTX (driver input)
  - board_pin: 4
    device: SN65HVD230 CAN Transceiver
    device_pin: "CTX"
    color: blue
  # CAN_RX = GPIO44 (physical pin 6) -> transceiver CRX (receiver output)
  - board_pin: 6
    device: SN65HVD230 CAN Transceiver
    device_pin: "CRX"
    color: green

Generate:

pinviz render examples/esp32_s3_can_transceiver.yaml -o esp32_s3_can.svg

Result:

ESP32-S3 CAN Transceiver

Board aliases: esp32_s3_devkitc1, esp32s3, esp32_s3 (use esp32_s3_devkitc1_schematic for the artwork-free variant)

ESP8266 NodeMCU - LED Example

Multiple LEDs with smart GND pin distribution using board_pin_role.

Result:

ESP8266 NodeMCU LEDs

Key Features: Smart pin assignment distributes GND connections across the NodeMCU's 4 GND pins automatically. See Smart Pin Assignment.

Board aliases: esp8266_nodemcu, esp8266, nodemcu

Wemos D1 Mini - OLED Display

I2C OLED display on the compact Wemos D1 Mini (16-pin dual-sided).

Result:

Wemos D1 Mini OLED

Key Features: Compact 16-pin form factor, I2C on GPIO4 (SDA) and GPIO5 (SCL). Good for space-constrained and battery-powered projects.

Board aliases: wemos_d1_mini, d1mini, wemos