# Rotary Dial

ESP32 firmware that reads a pulse-generating telephone rotary dial and publishes the dialled number to Home Assistant over MQTT.

The project is a standalone PlatformIO/Arduino firmware using WiFiManager for first-time Wi-Fi setup, LittleFS for local configuration storage, a small built-in web UI, and PubSubClient for MQTT.

## How It Works

A classic rotary telephone dial closes and opens contacts as the dial is wound and released. This firmware expects two contacts:

| Contact | GPIO | Purpose |
|---------|------|---------|
| Off-normal / active contact | GPIO 4 | Goes active while a digit is being dialled |
| Pulse contact | GPIO 5 | Generates the digit pulse train |

Both pins use `INPUT_PULLUP`, so each contact should switch the GPIO to GND when active.

When the off-normal contact goes low, the firmware starts a digit. While that contact remains low, it counts rising edges on the pulse contact. When the off-normal contact returns high, the digit is complete:

| Pulses | Digit |
|--------|-------|
| 1-9 | `1`-`9` |
| 10 or more | `0` |

Digits are appended to a string. After 3 seconds without another completed digit, the full number is published to MQTT. Leading zeros are preserved, so dialling `07` publishes `"07"`.

## Hardware

| Item | Details |
|------|---------|
| MCU | ESP32 board supported by the configured PlatformIO environments |
| Dial | Pulse-generating rotary telephone dial with off-normal and pulse contacts |
| Off-normal pin | GPIO 4 (`OFF_NORMAL_PIN` in `src/main.cpp`) |
| Pulse pin | GPIO 5 (`PULSE_PIN` in `src/main.cpp`) |
| Wiring | Each contact connects its GPIO to GND when active; firmware enables internal pull-ups |

If your dial uses inverted contact logic, adjust the state checks in `dialLoop()` rather than only changing an interrupt trigger. The current implementation polls both pins and does not use GPIO interrupts.

## Building and Flashing

Install PlatformIO, then run:

```bash
# Build the default ESP32 DevKit environment
pio run -e esp32dev

# Flash firmware
pio run -e esp32dev --target upload

# Upload the LittleFS image, including data/logo.png
pio run -e esp32dev --target uploadfs

# Serial monitor at 115200 baud
pio device monitor
```

The configured environments are:

| Environment | Board |
|-------------|-------|
| `esp32dev` | ESP32 Dev Module |
| `esp32-s3-devkitc-1` | ESP32-S3-DevKitC-1 |

Use the matching environment name in the commands above. Close the serial monitor before uploading firmware because it holds the serial port.

## First-Time Wi-Fi Setup

On first boot, WiFiManager opens an access point named `Rotary-Dial`. Connect with a phone or laptop and use the captive portal to enter Wi-Fi credentials.

The portal also exposes a `Device hostname` field. The default hostname is `rotary-dial`.

After the device joins Wi-Fi, it starts mDNS and the web UI is reachable at:

```text
http://rotary-dial.local
```

The serial monitor also prints the assigned IP address.

## Web UI

Browse to the device address to configure:

| Setting | Notes |
|---------|-------|
| Hostname | Saved to LittleFS; changing it restarts the device |
| Security | Optional HTTP basic auth, username `admin` |
| MQTT | Broker host, port, username, password, topic prefix, and enable switch |

Passwords are only replaced when a new non-empty password is submitted. Leaving an existing password field blank keeps the stored value.

The header logo is served from `/logo.png`, which comes from `data/logo.png` in the uploaded LittleFS image.

## HTTP API

| Method | Path | Description |
|--------|------|-------------|
| `GET` | `/` | HTML configuration page |
| `GET` | `/logo.png` | Logo image served from LittleFS |
| `POST` | `/config` | Save hostname, auth, and MQTT settings; redirects to `/`; restarts if hostname changed |
| `POST` | `/reset` | Restart the device immediately |

When HTTP auth is enabled, the username is `admin` and the password is the value configured in the web UI.

## MQTT

MQTT is disabled until it is enabled and configured in the web UI.

Default topic prefix: `dial`

| Direction | Topic | Description |
|-----------|-------|-------------|
| Published | `<prefix>/dialed` | Complete dialled number as a non-retained string event |
| Published | `<prefix>/status` | `online` on connect, `offline` as retained MQTT last will |
| Published | `homeassistant/sensor/<object_id>/config` | Retained Home Assistant discovery payload |

The firmware publishes Home Assistant MQTT discovery for a sensor named `Dialed Number`.

Example automation:

```yaml
automation:
  - alias: Act on dialled number
    trigger:
      platform: mqtt
      topic: dial/dialed
    action:
      - choose:
          - conditions:
              - condition: template
                value_template: "{{ trigger.payload == '112' }}"
            sequence:
              - service: notify.mobile_app
                data:
                  message: "Emergency number dialled!"
```

## Factory Reset

During boot, the firmware increments a reset counter in LittleFS and waits 3 seconds. Rapidly power-cycle or press EN before that window expires to accumulate reset counts.

| Rapid boot count | Effect |
|------------------|--------|
| 5-9 | Clears hostname, HTTP auth, and MQTT config |
| 10+ | Clears hostname, HTTP auth, MQTT config, and Wi-Fi credentials |

After the 3-second window, the counter is cleared if no reset threshold is reached.

Example serial output:

```text
[BOOT] reset count 3
[BOOT] reset count 4
[BOOT] reset count 5, triggering factory reset
[BOOT] factory reset triggered (clearWifi=0)!
[BOOT] factory reset complete, restarting...
```

## Tuning

The dial behavior is controlled by constants in `src/main.cpp`:

| Constant | Default | Description |
|----------|---------|-------------|
| `PULSE_DEBOUNCE_MS` | 20 ms | Minimum time between counted pulse release edges |
| `NUMBER_COMPLETE_MS` | 3000 ms | Idle time after the last completed digit before publishing the number |

The source also defines `DIGIT_BOUNDARY_MS`, but the current digit boundary is determined by the off-normal contact returning high.