multi-sensor

# Multi Sensor Example

This example shows how to use two HC-SR04 sensors in the same ESP-IDF application.

Each sensor has its own `hc_sr04_handle_t` instance.

The sensors are read sequentially to reduce acoustic cross-talk.

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## Hardware

Default GPIOs used by this example:

| Sensor | TRIG | ECHO |
|---|---:|---:|
| Front | GPIO4 | GPIO5 |
| Rear | GPIO18 | GPIO19 |

The HC-SR04 ECHO pin usually outputs 5 V. ESP32 GPIOs are not 5 V tolerant, so use a voltage divider or level shifter on each ECHO signal.

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## Build and Flash

From this example directory:

```bash
idf.py set-target esp32
idf.py build flash monitor
```

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## Expected Output

```text
I (1234) multi_sensor: front distance: 18.42 cm
I (1334) multi_sensor: rear distance: 42.10 cm
I (2434) multi_sensor: front distance: 18.39 cm
I (2534) multi_sensor: rear distance: 42.06 cm
```

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## Notes

Avoid triggering multiple ultrasonic sensors at the same time.

This example adds a short delay between readings:

```c
vTaskDelay(pdMS_TO_TICKS(100));
```

This reduces the chance of one sensor receiving the echo generated by another sensor.