meshtastic_firmware/variants/nrf52840/diy/moonshine_NRF52_ebyte/readme.md

Moonshine NRF52 ebyte

DIY Meshtastic node variant based on an Ebyte nRF52840 MCU module and E22-400M33S LoRa module.

Hardware

• MCU module: Ebyte nRF52840 (512 KB flash / 128 KB RAM)
• LF clock: 32.768 kHz crystal (USE_LFXO)
• LoRa: E22-400M33S (SX1268 + 33dBm PA, 2W, 433MHz) - SX126X_MAX_POWER=8, TX_GAIN_LORA=25. SX126X_RXEN (P1.09) is MCU-controlled by RadioLib; TXEN is driven by DIO2 (SX126X_DIO2_AS_RF_SWITCH). TCXO voltage 1.8V with TCXO_OPTIONAL fallback to XTAL.
• LED: Bluetooth pairing status on P0.15 (LED_PAIRING). Solid on = BLE connected, slow blink = unpaired, fast blink = pairing, off after 30s idle.
• Battery ADC: 0.5 voltage divider (equal resistors)
• USB CDC serial: enabled by default (nRF52840 built-in USB-ACM). Debug output and Meshtastic CLI communication go through the USB serial port.
• I2C: SDA/SCL pins wired (P0.08/P0.04) but no I2C devices connected.

Pin map

Function	Pin	Notes
LED	P0.15	Bluetooth pairing status
CHARGE_DET	P0.13	Active high (charging)
BUTTON	P0.24	User button
BUZZER	P1.11	PWM buzzer
BATTERY_ADC	P0.03	AIN1, 0.5 divider
IIC_SDA	P0.08	Wired, no device
IIC_SCL	P0.04	Wired, no device
SPI_MISO	P1.00
SPI_MOSI	P0.22
SPI_SCK	P0.20
LORA_CS	P0.17
LORA_DIO1	P1.10	IRQ
LORA_BUSY	P0.28	AIN4 (AI4)
LORA_RESET	P1.13
LORA_RXEN	P1.09	MCU-controlled RXEN; TXEN via DIO2

Build & Flash

Build

pio run -e moonshine_NRF52_ebyte

Uses PRIVATE_HW (HardwareModel 255) - no protobuf or architecture.h changes required.

The build links against nrf52840_s140_v6.ld, so the application is linked to start at 0x26000 and requires the S140 SoftDevice v6.x to be present on the chip at 0x0-0x25FFF. The build output (firmware-*.hex / .uf2) contains only the application, not the SoftDevice.

Flash via USB (nice!nano)

The nice!nano comes pre-flashed with the S140 v6 SoftDevice and the Adafruit UF2 bootloader. No SWD probe is needed - firmware can be uploaded over USB.

Method 1: PlatformIO serial DFU (recommended)

pio run -e moonshine_NRF52_ebyte -t upload

PlatformIO opens the USB CDC serial port at 1200 baud to trigger the DFU bootloader, then uploads via nrfutil serial DFU. The board automatically resets into the application after upload.

Method 2: UF2 drag-and-drop

1. Double-tap the Reset button to enter UF2 bootloader mode. A USB mass storage volume will appear (e.g. NRF52BOOT).
2. Copy the .uf2 file from .pio/build/moonshine_NRF52_ebyte/firmware-*.uf2 to the USB volume.
3. The board automatically resets into the application after the file transfer completes.

Flash via SWD (alternative)

If the SoftDevice or bootloader is missing or corrupted, flash via SWD with OpenOCD (CMSIS-DAP / J-Link / ST-Link):

# Full flow: recover (erase all + unlock) -> SoftDevice -> app -> reset
openocd -f interface/cmsis-dap.cfg -f target/nrf52.cfg \
  -c "init; nrf52_recover; \
      program bin/s140_nrf52_7.3.0_softdevice.hex verify; \
      program .pio/build/moonshine_NRF52_ebyte/firmware-*.hex verify; \
      reset run; exit"

When the SoftDevice is already on the chip and only the application changed, skip nrf52_recover and the SoftDevice line:

openocd -f interface/cmsis-dap.cfg -f target/nrf52.cfg \
  -c "init; \
      program .pio/build/moonshine_NRF52_ebyte/firmware-*.hex verify; \
      reset run; exit"

Notes

• The firmware hex filename contains a commit hash (e.g. 2.8.0.421838f); use the actual file produced by pio run or a shell glob.
• USB CDC serial is available immediately after boot for debug output and the Meshtastic Python CLI (meshtastic --noproto / meshtastic --info).
• MESHTASTIC_EXCLUDE_I2C=1 is set because no I2C devices are connected. Remove this flag from platformio.ini if an I2C display or sensor is added later.
• No GPS, screen, accelerometer, or magnetometer is configured. Remove the corresponding MESHTASTIC_EXCLUDE_* flags from platformio.ini if hardware is added.