+----------------------------------------------------------------------------------------------------+
|  NodeMCU v2 (ESP-12E/F)  ---  distance-sensor                                                      |
+----------------------------------------------------------------------------------------------------+
|  Rails: 5V, 3V3, GND                                                                               |
|                                                                                                    |
|  distance  [HC-SR04 ultrasonic distance sensor]  -- Ultrasonic Sensor                              |
|    VCC   -> rail 5V                                                                                |
|    GND   -> rail GND                                                                               |
|    TRIGGER -> D5                                                                                   |
|    ECHO  -> D6                                                                                     |
|                                                                                                    |
|  distancelight  [WS2812B addressable LED (NeoPixel)]  -- Distance Sensor Light                     |
|    VCC   -> rail 5V                                                                                |
|    GND   -> rail GND                                                                               |
|    DIN   -> D1                                                                                     |
|                                                                                                    |
|  Passives:                                                                                         |
|    c1: 100nF capacitor, distancelight.VCC  <->  GND   (decoupling neopixel)                        |
|                                                                                                    |
|  BOM:                                                                                              |
|    - NodeMCU v2 (ESP-12E/F)                                                                        |
|    - HC-SR04 ultrasonic distance sensor  (distance)                                                |
|    - WS2812B addressable LED (NeoPixel)  (distancelight)                                           |
|    - 1x 100nF capacitor                                                                            |
|                                                                                                    |
|  Power: ~35mA typical, ~90mA peak (budget 500mA)  OK                                               |
|                                                                                                    |
|  Warnings:                                                                                         |
|    [warn] echo_pin_5v: HC-SR04 ECHO is 5V; add a voltage divider to ESP8266 GPIO or use HC-SR04P.  |
+----------------------------------------------------------------------------------------------------+
