nRF21540 DK

Board Overview

nRF21540 DK

Name:

nrf21540dk

Vendor:

Nordic Semiconductor

Architecture:

arm

SoC:

nrf52840

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Overview

The nRF21540 DK (PCA10112) shows possibility of the Nordic Semiconductor nRF21540 Front End Module connected with nRF52840 ARM Cortex-M4F CPU. The CPU provides support for the following devices:

• ADC

• CLOCK

• FLASH

• GPIO

• I2C

• MPU

• NVIC

• PWM

• RADIO (Bluetooth Low Energy and 802.15.4)

• RTC

• Segger RTT (RTT Console)

• SPI

• UART

• USB

• WDT

More information about the board can be found at the nRF21540 website [2]. nRF21540 Product Specification [4] contains the processor’s and front end module’s information and the datasheet.

Hardware

The nRF52840 on the nRF21540 DK has two external oscillators. The frequency of the slow clock is 32.768 kHz. The frequency of the main clock is 32 MHz.

Supported Features

The nrf21540dk board supports the hardware features listed below.

on-chip / on-board

Feature integrated in the SoC / present on the board.

2 / 2

Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.

vnd,foo

Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

nrf21540dk

/

nrf52840

nrf21540dk@/nrf52840 target

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M4F CPU1	arm,cortex-m4f
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	nordic,nrf-saadc
	on-board	ADC channels exposed on Arduino Uno (R3) headers1	arduino,uno-adc
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	nordic,nrf-uicr
	on-chip	Nordic EGU (Event Generator Unit)6	nordic,nrf-egu
	on-chip	Nordic nRF family ACL (Access Control List)1	nordic,nrf-acl
	on-chip	Nordic nRF family MWU (Memory Watch Unit)1	nordic,nrf-mwu
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)1	nordic,nrf-pdm
Clock control	on-chip	Nordic nRF clock control node1	nordic,nrf-clock
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	nordic,nrf-comp
Counter	on-chip	Nordic nRF timer node5	nordic,nrf-timer
Cryptographic accelerator	on-chip	Nordic ECB (AES electronic codebook mode encryption)1	nordic,nrf-ecb
	on-chip	Nordic nRF family CCM (AES CCM mode encryption)1	nordic,nrf-ccm
	on-chip	ARM TrustZone CryptoCell 3101	arm,cryptocell-310
Debug	on-chip	ARMv7 instrumentation trace macrocell1	arm,armv7m-itm
Flash controller	on-chip	Nordic NVMC (Non-Volatile Memory Controller)1	nordic,nrf52-flash-controller
	on-chip	Properties defining the interface for the Nordic QSPI peripheral1	nordic,nrf-qspi
GPIO & Headers	on-chip	NRF5 GPIOTE1	nordic,nrf-gpiote
	on-chip	NRF5 GPIO2	nordic,nrf-gpio
	on-board	GPIO pins exposed on Arduino Uno (R3) headers1	arduino-header-r3
I2C	on-chip	Nordic nRF family TWI (TWI master)1 1	nordic,nrf-twi
I2S	on-chip	Nordic I2S (Inter-IC sound interface)1	nordic,nrf-i2s
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	nordic,nrf-ieee802154
Input	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ARMv7-M NVIC (Nested Vectored Interrupt Controller)1	arm,v7m-nvic
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
	on-board	Group of PWM-controlled LEDs1	pwm-leds
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	nordic,nrf-ficr
	on-chip	Nordic nRF family PPI (Programmable Peripheral Interconnect)1	nordic,nrf-ppi
MTD	on-chip	Flash node1	soc-nv-flash
	on-board	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
Networking	on-chip	Nordic nRF family RADIO peripheral1	nordic,nrf-radio
	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	nordic,nrf-nfct
	on-board	This is a SPI device interface to the nRF21540 Radio Front-End module1	nordic,nrf21540-fem-spi
	on-board	nRF21540 Radio Front-End module1	nordic,nrf21540-fem
Pin control	on-chip	The nRF pin controller is a singleton node responsible for controlling pin function selection and pin properties1	nordic,nrf-pinctrl
Power management	on-chip	Nordic nRF power control node1	nordic,nrf-power
PWM	on-chip	nRF PWM1 3	nordic,nrf-pwm
	on-chip	nRFx S/W PWM1	nordic,nrf-sw-pwm
Regulator	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	nordic,nrf5x-regulator
	on-chip	Nordic nRF52X regulator (high voltage stage of the main supply)1	nordic,nrf52x-regulator-hv
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device2	nordic,nrf-gpregret
RNG	on-chip	Nordic nRF family RNG (Random Number Generator)1	nordic,nrf-rng
RTC	on-chip	Nordic nRF RTC (Real-Time Counter)3	nordic,nrf-rtc
Sensors	on-chip	Nordic nRF family TEMP node1	nordic,nrf-temp
	on-chip	Nordic nRF quadrature decoder (QDEC) node1	nordic,nrf-qdec
Serial controller	on-chip	Nordic nRF family UARTE (UART with EasyDMA)1 1	nordic,nrf-uarte
SPI	on-chip	Nordic nRF family SPI (SPI master)1 2	nordic,nrf-spi
	on-chip	Nordic nRF family SPIM (SPI master with EasyDMA)1	nordic,nrf-spim
SRAM	on-chip	Generic on-chip SRAM1	mmio-sram
Timer	on-chip	ARMv7-M System Tick1	arm,armv7m-systick
USB	on-chip	Nordic nRF52 USB device controller1	nordic,nrf-usbd
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)1	nordic,nrf-wdt

See nRF52840 Product Specification [3] and nRF21540 DK Hardware guide [1] for a complete list of nRF21540 Development Kit board hardware features.

Connections and IOs

LED

• LED1 (green) = P0.13

• LED2 (green) = P0.14

• LED3 (green) = P0.15

• LED4 (green) = P0.16

Push buttons

• BUTTON1 = SW1 = P0.11

• BUTTON2 = SW2 = P0.12

• BUTTON3 = SW3 = P0.24

• BUTTON4 = SW4 = P0.25

• BOOT = SW5 = boot/reset

Front End Module

• MOSI = P1.13

• MISO = P1.14

• CLOCK = P1.15

• CHIP SELECT = P0.21

• PDN = P0.23

• MODE = P0.17

• RXEN = P0.19

• ANTSEL = P0.20

• TXEN = P0.22

Programming and Debugging

The nrf21540dk board supports the runners and associated west commands listed below.

	flash	debug	attach	debugserver	rtt
jlink	✅	✅ (default)	✅	✅	✅
nrfjprog	✅
nrfutil	✅ (default)
openocd	✅	✅	✅	✅	✅
pyocd	✅	✅	✅	✅	✅

Applications for the nrf21540dk/nrf52840 board configuration can be built, flashed, and debugged in the usual way. See Building an Application and Run an Application for more details on building and running.

Flashing

Follow the instructions in the Nordic nRF5x Segger J-Link page to install and configure all the necessary software. Further information can be found in Flashing. Then build and flash applications as usual (see Building an Application and Run an Application for more details).

Here is an example for the Hello World application.

First, run your favorite terminal program to listen for output.

$ minicom -D <tty_device> -b 115200

Replace <tty_device> with the port where the board nRF21540 DK can be found. For example, under Linux, /dev/ttyACM0.

Then build and flash the application in the usual way.

# From the root of the zephyr repository
west build -b nrf21540dk/nrf52840 samples/hello_world
west flash

Debugging

Refer to the Nordic nRF5x Segger J-Link page to learn about debugging Nordic boards with a Segger IC.

Testing the LEDs and buttons in the nRF21540 DK

There are 2 samples that allow you to test that the buttons (switches) and LEDs on the board are working properly with Zephyr:

samples/basic/blinky
samples/basic/button

You can build and flash the examples to make sure Zephyr is running correctly on your board. The button and LED definitions can be found in boards/nordic/nrf21540dk/nrf21540dk_nrf52840.dts.

Changing UART1 pins

The following approach can be used when an application needs to use another set of pins for UART1:

1. Add devicetree overlay file to the main directory of your application:

   &pinctrl {
      uart1_default_alt: uart1_default_alt {
         group1 {
            psels = <NRF_PSEL(UART_TX, 0, 14)>,
                    <NRF_PSEL(UART_RX, 0, 16)>;
         };
      };
      /* required if CONFIG_PM_DEVICE=y */
      uart1_sleep_alt: uart1_sleep_alt {
         group1 {
            psels = <NRF_PSEL(UART_TX, 0, 14)>,
                    <NRF_PSEL(UART_RX, 0, 16)>;
            low-power-enable;
         };
      };
   };
   
   &uart1 {
     pinctrl-0 = <&uart1_default_alt>;
     /* if sleep state is not used, use /delete-property/ pinctrl-1; and
      * skip the "sleep" entry.
      */
     pinctrl-1 = <&uart1_sleep_alt>;
     pinctrl-names = "default", "sleep";
   };
   

   In the overlay file above, pin P0.16 is used for RX and P0.14 is used for TX

See Set devicetree overlays for further details.

Selecting the pins

Pins can be configured in the board pinctrl file. To see the available mappings, open the nRF52840 Product Specification [3], chapter 7 ‘Hardware and Layout’. In the table 7.1.1 ‘aQFN73 ball assignments’ select the pins marked ‘General purpose I/O’. Note that pins marked as ‘low frequency I/O only’ can only be used in under-10KHz applications. They are not suitable for 115200 speed of UART.

References

[1]

https://docs.nordicsemi.com/bundle/ug_nrf21540_dk/page/UG/nrf21540_DK/intro.html

[2]

https://www.nordicsemi.com/Products/Low-power-short-range-wireless/nRF21540

[3] (1,2)

https://docs.nordicsemi.com/bundle/ps_nrf52840/page/keyfeatures_html5.html

[4]

https://docs.nordicsemi.com/bundle/ps_nrf21540/page/keyfeatures_html5.html