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Getting Started

OpenDTU supports the ESP32 family of microcontrollers.

Depending on the inverter to be addressed, different RF modules are required.

  • The HM series requires the NRF24L01+ module
  • The HMS/HMT series requires the CMT2300A module

Please see the inverter overview to see if your inverter is supported and to determine the required RF module.

For an easy start, use a "NodeMCU32 ESP32 DEVKIT DOIT" or "ESP32 NodeMCU Development Board" with an ESP32-S3 or ESP-WROOM-32 chipset on it.

Sample Picture:

NodeMCU-ESP32

Boards with Ethernet-Connector and Power-over-Ethernet are also supported. For example Olimex ESP32-POE or LilyGo T-Internet-POE

Steps to build your own DTU

Use of GPIOs

In general, ESP32 chips allow to use any function on any GPIO pin. There are a few restrictions, which are documented at the respective ESP32(-S3) DevKit subpages. Freely wire the logic pins between your ESP32(-S3) module and peripheral components. The important bit is to create and use a matching device profile.

  1. Determine the RF module you need
  2. Get a ESP32 module.
  3. Use a power suppy with 5 V and 1 A. The USB cable connected to your PC/Notebook may be powerful enough or may be not. Also the quality of the used USB cable might have an impact.
  4. Wire the module and RF module
  5. Wire a optional display
  6. Wire optional LEDs
  7. Flash the firmware via USB
  8. Create, upload, and select a matching device profile which describes your hardware (or look at a profile first and connect the logic pins accordingly).