# Simplified Wiring Diagram

## The Key Insight: One Driver for Everything! 🎯

**You only need ONE LM18200 H-Bridge driver** - it handles both DC and DCC modes.

The ESP32 just sends different signals to the same pins depending on which mode you select:

```
         ESP32-2432S028R
         ┌─────────────┐
         │             │
GPIO 18 ─┤PWM / DCC_A  │───┐
GPIO 19 ─┤DIR / DCC_B  │───┤
GPIO 23 ─┤BRAKE        │───┤
GPIO 4  ─┤RELAY        │───┼──→ To Relay Module
GND     ─┤             │───┤
5V      ─┤             │───┤
         └─────────────┘   │
                           │
                           ↓
                   LM18200 H-Bridge
                   ┌──────────────┐
        GPIO 18 ───┤ PWM Input    │
        GPIO 19 ───┤ DIR Input    │
        GPIO 23 ───┤ BRAKE        │
        GND     ───┤ GND          │
        5V      ───┤ VCC (logic)  │
        12-18V  ───┤ VS (power)   │
                   │              │
                   │  OUT1  OUT2  │
                   └───┬──────┬───┘
                       │      │
                       ↓      ↓
                   Track Rail 1 & 2
```

## How It Works

### DC Analog Mode
When you select **DC Analog** mode in the UI:
- GPIO 18 outputs **20kHz PWM** (0-100% duty cycle for speed)
- GPIO 19 outputs **HIGH or LOW** (sets direction: FWD or REV)
- LM18200 amplifies this to create variable DC voltage on the track
- Your DC locomotive responds to the voltage

### DCC Digital Mode
When you select **DCC** mode in the UI:
- GPIO 18 outputs **DCC Signal A** (square wave: 58μs or 100μs pulses)
- GPIO 19 outputs **DCC Signal B** (inverted version of Signal A)
- LM18200 amplifies these to create DCC waveform on the track
- Your DCC decoder locomotive responds to the digital commands

## Complete Connection List

### LM18200 to ESP32
| LM18200 Pin | ESP32 GPIO | Purpose |
|-------------|------------|---------|
| PWM Input | 18 | Speed (DC) / DCC Signal A (DCC) |
| Direction Input | 19 | Direction (DC) / DCC Signal B (DCC) |
| Brake Input | 23 | Emergency stop |
| GND | GND | Ground reference |
| VCC (logic) | 5V | Control logic power |

### LM18200 Power & Outputs
| LM18200 Pin | Connection | Purpose |
|-------------|------------|---------|
| VS (motor power) | 12-18V supply + | High current power |
| GND (power) | 12-18V supply - | Power ground |
| OUT1 | Track Rail 1 | Amplified output |
| OUT2 | Track Rail 2 | Amplified output |

### Relay Module (2-rail/3-rail switching)
| Relay Pin | ESP32 GPIO | Purpose |
|-----------|------------|---------|
| Signal IN | 4 | Relay control |
| VCC | 5V | Relay power |
| GND | GND | Ground |

### Power Supply Connections
```
12-18V Power Supply
    ├─→ LM18200 VS (motor power)
    ├─→ DC-DC Buck Converter → 5V → ESP32 + Relay + LM18200 VCC
    └─→ GND (common ground)
```

## Why This Works

The LM18200 is just an amplifier. It doesn't care if you're feeding it:
- PWM signals (for DC speed control)
- DCC square waves (for digital commands)

It simply takes the 3.3V logic signals from the ESP32 and amplifies them to track voltage (12-18V).

**In DC mode**: The amplified PWM creates variable DC voltage
**In DCC mode**: The amplified square waves create the DCC signal

## Safety Notes

✅ **Always power OFF before switching modes** (automatic in the UI)
✅ **Common ground** - All GND connections must be tied together
✅ **Heat sink** - LM18200 can get hot, use appropriate heat sinking
✅ **Fusing** - Add fuse on track output for overcurrent protection

## No Separate DCC Booster Needed!

You do **NOT** need:
- ❌ Separate DCC booster circuit
- ❌ Different outputs for DC vs DCC
- ❌ Mode selection switches in hardware

Everything is handled in software by the ESP32 touchscreen UI.

---

**Bottom Line**: Wire up ONE LM18200, and you're done. The ESP32 software handles the rest!