# Building the Firmware

## Prerequisites

- [PlatformIO](https://platformio.org/) (CLI or IDE)
- MeshCore library at `../MeshCore`

## Build Commands

```bash
# Full build
pio run

# Clean build (removes all artifacts)
pio run -t clean && pio run

# Verbose build (shows compiler commands)
pio run -v
```

## Build Output

After a successful build:

```
RAM:   17.6% (57KB / 320KB)
Flash: 32.0% (1.0MB / 3.3MB)
```

**Output files in `.pio/build/heltec_v3_repeater/`:**

| File | Size | Purpose |
|------|------|---------|
| `firmware.bin` | ~1.1 MB | OTA updates |
| `firmware.elf` | ~2.5 MB | Debugging |
| `firmware.factory.bin` | ~1.2 MB | Initial flash (includes bootloader) |

## Build Configuration

Key settings in `platformio.ini`:

### LoRa Parameters

```ini
-D LORA_FREQ=910.525    # Frequency in MHz
-D LORA_BW=62.5         # Bandwidth in kHz
-D LORA_SF=7            # Spreading factor (7-12)
-D LORA_CR=5            # Coding rate (5-8)
-D LORA_TX_POWER=22     # TX power in dBm
```

### Debug Options

Uncomment to enable:

```ini
; -D MESH_PACKET_LOGGING=1   # Log all mesh packets
; -D MESH_DEBUG=1            # Verbose debug output
```

## Troubleshooting

### Missing MeshCore

```
Error: symlink://../MeshCore not found
```

Ensure MeshCore exists at the expected path:
```bash
ls ../MeshCore/library.json
```

### Library Dependency Errors

Clear the library cache:
```bash
rm -rf .pio/libdeps
pio run
```