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|  ESP32-DevKitC-V4  ---  nextion-thermostat                                                                     |
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|  Rails: 5V, 3V3, GND                                                                                           |
|                                                                                                                |
|  screen  [Nextion HMI display (UART, 9600 baud default)]  -- Thermostat                                        |
|    VCC   -> rail 5V                                                                                            |
|    GND   -> rail GND                                                                                           |
|    TX    -> nextion_uart (GPIO16)                                                                              |
|    RX    -> nextion_uart (GPIO17)                                                                              |
|                                                                                                                |
|  th  [Sensirion SHT3x / SHT4x temperature + humidity (I2C)]  -- Room                                           |
|    VCC   -> rail 3V3                                                                                           |
|    GND   -> rail GND                                                                                           |
|    SDA   -> i2c0 (GPIO21)                                                                                      |
|    SCL   -> i2c0 (GPIO22)                                                                                      |
|                                                                                                                |
|  Passives:                                                                                                     |
|    c1: 100uF capacitor, screen.VCC  <->  GND   (bulk decoupling nextion backlight inrush)                      |
|    c2: 100nF capacitor, screen.VCC  <->  GND   (decoupling nextion logic)                                      |
|    c3: 100nF capacitor, th.VCC  <->  GND   (decoupling sht3xd)                                                 |
|                                                                                                                |
|  BOM:                                                                                                          |
|    - ESP32-DevKitC-V4                                                                                          |
|    - Nextion HMI display (UART, 9600 baud default)  (screen)                                                   |
|    - Sensirion SHT3x / SHT4x temperature + humidity (I2C)  (th)                                                |
|    - 1x 100uF capacitor                                                                                        |
|    - 2x 100nF capacitor                                                                                        |
|                                                                                                                |
|  Power: ~90mA typical, ~251mA peak (budget 800mA)  OK                                                          |
|                                                                                                                |
|  Warnings:                                                                                                     |
|    [info] nextion_5v_supply: The Nextion's VCC rides the board's 5V rail (USB) -- a Nextion at full backlight  |
|                              pulls 200-250mA. Check your USB supply margin or feed the display from a          |
|                              separate 5V brick if you're also driving WS2812 strips off the same regulator.    |
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