Ebus + esp

ESPHome
1

Hello all,
I am trying to control my vaillant ecotec boiler.
I built an adapter that can be found at
https://github.com/xyzroe/eBus-TTL-adapter/ and connected to an esp wroom32
I tried to integrate with esphome + ebusd on ha
esphome code is uploaded and connecting to ebusd.
But i dont see any scan or detection of boiler.
is there anybody that used this pcb?

tx/rx leds are blinking fine on the board

my esphome config is

esphome:
  name: ebus-gateway
  min_version: 2025.11.0

esp32:
  board: esp32dev
  variant: esp32
  framework:
    type: arduino
    advanced:
      minimum_chip_revision: "3.0"

uart:
  id: uart_bus
  tx_pin: GPIO21
  rx_pin: GPIO12
  baud_rate: 2400
  parity: NONE
  stop_bits: 1
  rx_buffer_size: 1024


stream_server:
  uart_id: uart_bus
  port: 3333
external_components:
  - source: github://oxan/esphome-stream-server
2

with this config

uart:
  id: uart_bus
  tx_pin:
    number: GPIO19
    inverted: true  
#  tx_pin: GPIO19
  rx_pin: GPIO22
  baud_rate: 2400
  debug:
    direction: BOTH
    dummy_receiver: false
    after:
      delimiter: "\xAA" # eBus paket başlangıcı genelde AA hex kodudur
  parity: NONE
  stop_bits: 1
  rx_buffer_size: 1024

" RX works fine… But i cant communicate with boiler… (TX invert mode was with my tries… i tried all possiblities but no chance)

3

I’m interested in this too, especially to enable an ESPHome programmed ESP32-C3 board for communication with the eBusd integration. Have a homegrown adapter with some additional features. While my hardware is different, I will try to use your software approach to see if there are problems on side of the software.
What I see as possible problems at the hardware in your approach: The adapter has 5V TTL-levels, that is too high on the RX-pin for ESP, they need 3.3V max. More voltage can lead to damage or other problems. It’s easy to fix: Just connect the 5V pin of the connector to the 3V3 supply of the ESP. The TX-pin may see a bit of overload, you can replace R13 with a 560-1k one. The LEDs don’t need that much current. While I have some doubts that this really causes TX to fail, at least the 5V/3V3 should be fixed.