ESPHome external component: setup() and loop() never called on Component + UARTDevice

ESPHome
1

ESPHome external component: setup() and loop() never called on Component + UARTDevice

Summary

I have an external ESPHome component for controlling a Tesla Wall Connector Gen 2 via RS485. The component is correctly registered via App.register_component() in the generated main.cpp, but setup() and loop() are never called. Even with ESP_LOGE as the very first line of setup(), nothing appears in the logs.

Environment

  • ESPHome version: 2026.2.0
  • Board: Olimex ESP32-POE-ISO (esp32-poe-iso)
  • Framework: Arduino
  • Python: 3.14.5

Component structure

The component inherits from Component, uart::UARTDevice and TeslaControllerIO:

class TWCController : public Component, public uart::UARTDevice, public TeslaControllerIO {
public:
    void setup() override;
    void loop() override;
    void dump_config() override;
    ...
};

The __init__.py registers it like this:

async def to_code(config):
    var = cg.new_Pvariable(config[CONF_ID])
    await cg.register_component(var, config)
    await uart.register_uart_device(var, config)
    ...

Generated main.cpp (relevant part)

twc = new twc_controller::TWCController();
twc->set_component_source(LOG_STR("twc-controller"));
App.register_component(twc);
twc->set_uart_parent(twc_uart);
...
App.setup();  // called at line 613

So App.register_component(twc) IS called, and App.setup() IS called. But setup() inside the component is never reached.

What I see in logs

dump_config() IS called (showing TWC ID, min/max current, flow control pin), but setup() is never called. Even this does not appear:

void TWCController::setup() {
    ESP_LOGE(TAG, "SETUP CALLED!!!");  // never appears in logs
}

What I tried

  • Changed inheritance order (Component first, then UARTDevice)
  • Changed get_setup_priority() from AFTER_CONNECTION to DATA
  • Moved initialization to loop() with initialized flag — loop() is also never called
  • Cleared build cache completely
  • Downgraded ESPHome to 2026.2.0

Question

Why would setup() and loop() not be called on a component that is registered via App.register_component()? Is there something about combining Component with uart::UARTDevice registration that prevents this?

The component is based on https://github.com/jnicolson/esphome-twc-controller

Any help appreciated.

2

You may find the latest release has quite a number of updates, and a careful read of the March, April and May release notes as well may offer you some solutions as the UART section has received some love recently.

3

Specifically look at this section in the breaking changes:

PollingComponent() default constructor: now initializes to SCHEDULER_DONT_RUN (UINT32_MAX) instead of 1. External components that bypass codegen, call PollingComponent() with no argument, and never call set_update_interval() will stop polling. Pass an interval to the constructor or call set_update_interval() explicitly #15832
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