Nuttx Guide

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English

中文 (Chinese)
한국어 (Korean)
Мови (Ukrainian)

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Seeed Studio XIAO nRF52840 ​

chip:nrf52, chip:nrf52840

The Seeed Studio XIAO nRF52840 is a general purpose board supplied by Seeed Studio and it is compatible with the Nordic nRF52840 ecosystem as they share the same MCU.

Features ​

  • Nordic nRF52840, ARM® Cortex®-M4 32-bit processor with FPU, 64 MHz
  • 256 KB RAM,1MB Flash 2MB onboard Flash
  • Bluetooth 5.0/BLE/NFC
  • 1xUART, 1xI2C, 1xSPI, 1xNFC, 1xSWD, 11xGPIO(PWM)
  • USB Type-C interface
  • 1 RGB LED, 1 charge LED
  • 1 RESET button

Serial Console ​

By default, a serial console appears on pins 6 (TX P1.11) and pin 7 (RX P1.12). This console runs a 115200-8N1. The board can be configured to use the USB connection as the serial console.

User LED ​

The RGB LED is connected as follows:

Color Pin

RED P0.26 GREEN P0.30 BLUE P0.6

Buttons ​

The Reset button can be used to enter bootloader mode by rapidly clicking it twice. Then, it will enumerate as a storage device to a computer connected via USB. Saving a .UF2 file to this device will replace the Flash ROM contents on the nRF52840.

Pin Mapping ​

Pads numbered anticlockwise from USB connector.

Pad Signal Notes

0 P0.02 D0/A0 1 P0.03 D1/A1 2 P0.28 D2/A2 3 P0.29 D3/A3 4 P0.04 D4/SDA 5 P0.05 D5/SCL 6 P1.11 Default TX for UART0 serial console 7 P1.12 Default RX for UART0 serial console 8 P1.13 D8/SCK 9 P1.14 D9/MISO 10 P1.15 D10/MOSI 11 12 3V3 Ground Power output to peripherals 13 VIN +5V Supply to board

Power Supply ​

The working voltage of the MCU is 3.3V. Voltage input connected to general I/O pins may cause chip damage if it's higher than 3.3V.

Installation ​

  1. Download UF2 Tools:
 git clone https://github.com/microsoft/uf2.git
  1. Configure and build NuttX:
 git clone https://github.com/apache/nuttx.git nuttx
 git clone https://github.com/apache/nuttx-apps.git apps
 cd nuttx
 make distclean
 ./tools/configure.sh xiao-nrf52840:nsh
 make V=1
  1. Convert nuttx.hex to UF2 format using U2F Tools:
 python3 uf2/utils/uf2conv.py -c -f 0xADA52840 -i nuttx.hex -o nuttx.uf2

4. Connect the Seeed Studio XIAO nRF52840, and enter bootloader mode by rapidly clicking it twice. The board will be detected as a USB Mass Storage Device. Then copy "nuttx.uf2" into the device.

  1. To access the console, TX and RX pins must be connected to the device such as USB-serial converter.

Configurations ​

nsh ​

Basic NuttShell configuration (console enabled in UART0, at 115200 bps).

usbnsh ​

Basic NuttShell configuration using CDC/ACM serial (console enabled in USB Port, at 115200 bps).

jumbo ​

This configuration enabled NuttShell via USB and enabled leds and gpio examples:

Testing leds:

nsh> leds
leds_main: Starting the led_daemon
leds_main: led_daemon started

led_daemon (pid# 3): Running
led_daemon: Opening /dev/userleds
led_daemon: Supported LEDs 0x07
led_daemon: LED set 0x01
nsh> led_daemon: LED set 0x02
led_daemon: LED set 0x03
led_daemon: LED set 0x04
led_daemon: LED set 0x05
led_daemon: LED set 0x06
led_daemon: LED set 0x07

Testing gpios:

PIN/GPIO Mode Device

D0/P0.02 Input /dev/gpio0 D2/P0.28 Output /dev/gpio1 D1/P0.03 Input /dev/gpio2

nsh> gpio /dev/gpio0
Driver: /dev/gpio0
  Input pin:     Value=0
nsh> gpio /dev/gpio0
Driver: /dev/gpio0
  Input pin:     Value=1

nsh> gpio -o 0 /dev/gpio1
Driver: /dev/gpio1
  Output pin:    Value=1
  Writing:       Value=0
  Verify:        Value=0

nsh> gpio -w 1 /dev/gpio2
Driver: /dev/gpio2
  Interrupt pin: Value=0
  Verify:        Value=1