+-----------------------------------------------------------------------+
|  ESP32-DevKitC-V4  ---  weather-station                               |
+-----------------------------------------------------------------------+
|  Rails: 5V, 3V3, GND                                                  |
|                                                                       |
|  baro  [Bosch BMP280 (T/P)]  -- Weather pressure                      |
|    VCC   -> rail 3V3                                                  |
|    GND   -> rail GND                                                  |
|    SDA   -> i2c0 (GPIO21)                                             |
|    SCL   -> i2c0 (GPIO22)                                             |
|                                                                       |
|  climate  [HTU21D temperature + humidity (I2C)]  -- Weather climate   |
|    VCC   -> rail 3V3                                                  |
|    GND   -> rail GND                                                  |
|    SDA   -> i2c0 (GPIO21)                                             |
|    SCL   -> i2c0 (GPIO22)                                             |
|                                                                       |
|  lux  [TSL2561 ambient light sensor (lux, I2C)]  -- Weather light     |
|    VCC   -> rail 3V3                                                  |
|    GND   -> rail GND                                                  |
|    SDA   -> i2c0 (GPIO21)                                             |
|    SCL   -> i2c0 (GPIO22)                                             |
|                                                                       |
|  Passives:                                                            |
|    c1: 100nF capacitor, baro.VCC  <->  GND   (decoupling baro)        |
|    c2: 100nF capacitor, climate.VCC  <->  GND   (decoupling climate)  |
|    c3: 100nF capacitor, lux.VCC  <->  GND   (decoupling lux)          |
|    r1: 4.7k resistor, i2c0.SDA  <->  3V3   (I2C pull-up)              |
|    r2: 4.7k resistor, i2c0.SCL  <->  3V3   (I2C pull-up)              |
|                                                                       |
|  BOM:                                                                 |
|    - ESP32-DevKitC-V4                                                 |
|    - Bosch BMP280 (T/P)  (baro)                                       |
|    - HTU21D temperature + humidity (I2C)  (climate)                   |
|    - TSL2561 ambient light sensor (lux, I2C)  (lux)                   |
|    - 3x 100nF capacitor                                               |
|    - 2x 4.7k resistor                                                 |
|                                                                       |
|  Power: ~1mA typical, ~2mA peak (budget 500mA)  OK                    |
|                                                                       |
|  Warnings: none                                                       |
+-----------------------------------------------------------------------+
