# Moonshine ESP-C3

DIY Meshtastic node variant based on the ESP32-C3 + EBYTE 433 MHz LoRa module.

## Hardware

- **MCU**: ESP32-C3 with 4 MB external SPI flash
- **LoRa**: one of three EBYTE 433 MHz modules (see [LoRa module selection](#lora-module-selection))
- **USB CDC**: enabled (`ARDUINO_USB_MODE=1`, `ARDUINO_USB_CDC_ON_BOOT=1`) -
  serial console is exposed via the USB CDC port, no separate UART chip
- **Battery ADC**: 0.5 voltage divider on GPIO1 (`ADC_MULTIPLIER = 2.0`)
- **No screen, no GPS** on this board

## LoRa module selection

This board supports three EBYTE 433 MHz LoRa modules. Select the module by
commenting/uncommenting the `#define` lines at the top of `variant.h`:

```cpp
#define E220_400M30S
//#define E220_400M33S
//#define E22_400M33S
```

Only one module should be enabled at a time.

| Module       | Chip   | Power        | `USE_*`      | `TX_GAIN_LORA` | `SX126X_MAX_POWER` | Total output    |
| ------------ | ------ | ------------ | ------------ | -------------- | ------------------ | --------------- |
| E220-400M30S | LLCC68 | 30 dBm (1 W) | `USE_LLCC68` | 8              | 22                 | 22 + 8 = 30 dBm |
| E220-400M33S | LLCC68 | 33 dBm (2 W) | `USE_LLCC68` | 11             | 22                 | 22 + 11 = 33 dBm |
| E22-400M33S  | SX1268 | 33 dBm (2 W) | `USE_SX1268` | 25             | 8                  | 8 + 25 = 33 dBm  |

### E22-400M33S power note

The E22-400M33S has a high-gain PA (~25 dB). The variant limits the SX1268
chip output to 8 dBm (`SX126X_MAX_POWER = 8`), which the PA amplifies to
~33 dBm. Do **not** raise `SX126X_MAX_POWER` above 8 without verifying
actual PA output and current draw - overdriving the PA can cause large
current spikes and system resets.

See `variants/nrf52840/diy/moonshine_NRF52/variant.h` for the same module
wired with a more conservative power profile (`SX126X_MAX_POWER = 2`,
~27 dBm output).

## Pin map

| Function      | GPIO | Notes                                  |
| ------------- | ---- | -------------------------------------- |
| BUTTON        | 9    | BOOT button                            |
| LED           | 0    | Active high (`LED_STATE_ON = 1`)       |
| BATTERY_ADC   | 1    | 0.5 divider (`ADC_MULTIPLIER = 2.0`)   |
| LORA_RXEN     | 2    | RF switch RX enable                    |
| LORA_DIO1     | 3    | IRQ                                    |
| LORA_BUSY     | 4    |                                        |
| LORA_RESET    | 5    |                                        |
| LORA_MISO     | 6    |                                        |
| LORA_MOSI     | 7    |                                        |
| LORA_CS       | 8    |                                        |
| LORA_SCK      | 10   |                                        |

DIO2 drives the module's TXEN pin internally (`SX126X_DIO2_AS_RF_SWITCH`), so
`SX126X_TXEN` is left as `RADIOLIB_NC`. `SX126X_RXEN` is driven by GPIO2.

## Build & Flash

### Build

```sh
pio run -e moonshine_ESP_C3
```

Uses `PRIVATE_HW` (HardwareModel 255) - no protobuf or `architecture.h`
changes required. Board level is `extra` (built only on full releases).

### Flash

```sh
pio run -e moonshine_ESP_C3 -t upload --upload-port <port>
```

The board boots into USB CDC mode, so the serial console appears as a CDC
ACM port (`/dev/ttyACM*` on Linux/macOS, `COMx` on Windows) at 115200 baud.