+------------------------------------------------------------------------------------------------------------------------+
|  ESP32-DevKitC-V4  ---  rs485-energy                                                                                   |
+------------------------------------------------------------------------------------------------------------------------+
|  Rails: 5V, 3V3, GND                                                                                                   |
|                                                                                                                        |
|  rs485_bus  [Modbus RTU bus protocol (RS485-over-UART)]  -- RS485 modbus                                               |
|    UART  -> modbus_uart (uart)                                                                                         |
|    FLOW  -> GPIO5                                                                                                      |
|                                                                                                                        |
|  meter  [Eastron SDM single/three-phase energy meter (Modbus RTU over RS485)]  -- Mains                                |
|                                                                                                                        |
|  BOM:                                                                                                                  |
|    - ESP32-DevKitC-V4                                                                                                  |
|    - Modbus RTU bus protocol (RS485-over-UART)  (rs485_bus)                                                            |
|    - Eastron SDM single/three-phase energy meter (Modbus RTU over RS485)  (meter)                                      |
|                                                                                                                        |
|  Power: ~0mA typical, ~0mA peak (budget 500mA)  OK                                                                     |
|                                                                                                                        |
|  Warnings:                                                                                                             |
|    [info] rs485_transceiver_required: Wire UART RX/TX through a MAX485 (or equivalent) transceiver: A/B to the SDM230  |
|                                       terminals 9/10, RO/DI to GPIO16/GPIO17, DE+RE tied together to GPIO5.            |
+------------------------------------------------------------------------------------------------------------------------+