NRF52 Platform

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NRF52 Platform

This component contains platform-specific options for the NRF52 platform.

ℹ️ Note

Support for all aspects of ESPHome on the NRF52 is still in development.

# Example configuration entry
nrf52:
  board: adafruit_feather_nrf52840

Configuration variables

  • board (Required, string): The board type. Valid options are adafruit_feather_nrf52840, adafruit_itsybitsy_nrf52840, xiao_ble. Other boards should work with those configuration as well.
  • bootloader (Optional, string): Bootloader type. Valid options are mcuboot, adafruit, adafruit_nrf52_sd132, adafruit_nrf52_sd140_v6, adafruit_nrf52_sd140_v7. Default value depends on board type.

Getting Started

The nRF52840 requires a bootloader, with two supported options: MCUboot and Adafruit nRF52 Bootloader. It is recommended to use MCUboot as it supports OTA (Over-The-Air) updates. Your board most likely comes with a manufacturer-provided bootloader. ESPHome determines the bootloader type based on the board name.

Examples of low power nRF52840 boards.

Flashing with MCUboot

Flashing this bootloader requires an SWD connection, for which a programmer is necessary. A cheap ST-Link V2 can be utilized.

  1. Connect the board to the PC via SWD.
  2. Run esphome upload yourfile.yaml --device PYOCD.
# Example configuration entry
nrf52:
  board: adafruit_feather_nrf52840

Flashing with Adafruit nRF52 Bootloader

For flashing via a flash drive.

  1. Connect the board to the PC via USB.
  2. Quickly short the reset pin to ground twice.
  3. Copy the UF2 package to the flash drive.

This bootloader supports updates over USB CDC.

  1. Connect the board to the PC via USB.
  2. Quickly short the reset pin to ground twice.
  3. Run esphome upload yourfile.yaml.
# Example configuration entry
nrf52:
  board: adafruit_itsybitsy_nrf52840

GPIO Pin Numbering

There are two ways to reference GPIO pins:

  1. By pin name, e.g., P0.15 or P1.11.
  2. By pin number, e.g., 15 or 43.

DFU (Device Firmware Update)

The dfu component enables automatic entry into DFU (Device Firmware Update) mode by monitoring the USB CDC serial connection. When a host opens the port at 1200 baud, the component triggers a reset via a GPIO pin to put the device into DFU mode.

ESPHome uses this component internally when uploading firmware via:

esphome upload d.yaml

Example Configuration 

nrf52:
  dfu:
    reset_pin:
      number: 14
      inverted: true

Configuration variables

  • reset_pin (Required, Pin): The pin to use for trigger a hardware reset. This pin should be connected to the MCU’s reset line or to a circuit that causes the bootloader to enter DFU mode after reset.

REGOUT0

Output voltage from the REG0 regulator stage, which powers the GPIO pins when the board operates in high-voltage mode. This setting can only be changed a limited number of times, unless uicr_erase is set to true. Requires mcuboot or adafruit bootloader version 0.9.3 or higher.

Example Configuration 

nrf52:
  reg0:
    voltage: 3.3V
    uicr_erase: true

Configuration variables

  • voltage (Required, voltage): The desired output voltage - must be one of 1.8V, 2.1V, 2.4V, 2.7V, 3.0V, 3.3V.
  • uicr_erase (Optional, bool): If set to true, the User Information Configuration Registers (UICR) will be erased before writing the new voltage setting. ⚠️ Warning: Enabling this may cause the board to fail to boot if misconfigured. Default is false.

Troubleshooting

Flashing is unstable

If you are using the Adafruit bootloader, upgrade to the latest version: Adafruit nRF52 Bootloader Releases

How to start

Try minimum LED blinking config for the board:

supermini-nrf52840

nrf52:
  board: adafruit_itsybitsy_nrf52840

esphome:
  name: supermini-nrf52840

logger:
  level: DEBUG

output:
  - platform: gpio
    pin: P0.15
    id: red_led

interval:
  - interval: 1s
    then:
      - output.turn_on: red_led
      - delay: 0.5s
      - output.turn_off: red_led

xiao-nrf52840

nrf52:
  board: xiao_ble

esphome:
  name: xiao-nrf52840

logger:
  level: DEBUG

output:
  - platform: gpio
    pin: P0.26
    id: red_led

interval:
  - interval: 1s
    then:
      - output.turn_on: red_led
      - delay: 0.5s
      - output.turn_off: red_led

Board does not boot

Disable DC/DC:

nrf52:
  dcdc: false

See Also

NRF52 Platform

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