This is the documentation for the latest (main) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down menu on the left and select the desired version.

NXP FRDM-KW41Z¶

Overview¶

The FRDM-KW41Z is a development kit enabled by the Kinetis® W series KW41Z/31Z/21Z (KW41Z) family built on ARM® Cortex®-M0+ processor with integrated 2.4 GHz transceiver supporting Bluetooth® Smart/Bluetooth® Low Energy (BLE) v4.2, Generic FSK, IEEE® 802.15.4 and Thread.

The FRDM-KW41Z kit contains two Freedom boards that can be used as a development board or a shield to connect to a host processor. The FRDM-KW41Z is form-factor compatible with the Arduino™ R3 pin layout for more expansion options.

The FRDM-KW41Z highly-sensitive, optimized 2.4 GHz radio features a PCB F-antenna which can be bypassed to test via SMA connection, multiple power supply options, push/capacitive touch buttons, switches, LEDs and integrated sensors.

Hardware¶

Can be configured as Host or Shield for connection to Host Processor
Supports all DC-DC configurations (Buck, Boost, Bypass)
PCB inverted F-type antenna
SMA RF Connector
RF regulatory certified
Serial Flash for OTA firmware upgrades
On board NXP FXOS8700CQ digital sensor, 3D Accelerometer ( ±2g/ ±4g/ ±8g) + 3D Magnetometer
OpenSDA and JTAG debug

For more information about the KW41Z SoC and FRDM-KW41Z board:

Supported Features¶

The frdm_kw41z board configuration supports the following hardware features:

Interface	Controller	Driver/Component
NVIC	on-chip	nested vector interrupt controller
SYSTICK	on-chip	systick
PINMUX	on-chip	pinmux
COUNTER	on-chip	rtc
GPIO	on-chip	gpio
I2C	on-chip	i2c
SPI	on-chip	spi
ADC	on-chip	adc
UART	on-chip	serial port-polling; serial port-interrupt
FLASH	on-chip	soc flash
SENSOR	off-chip	fxos8700 polling: fxos8700 trigger
PWM \| on-chip \| tpm

The default configuration can be found in the defconfig file:

boards/arm/frdm_kw41z/frdm_kw41z_defconfig

Other hardware features are not currently supported by the port.

Connections and IOs¶

The KW41Z SoC has three pairs of pinmux/gpio controllers, but only two are currently enabled (PORTA/GPIOA and PORTC/GPIOC) for the FRDM-KW41Z board.

Name	Function	Usage
PTC1	GPIO	Red LED / FXOS8700 INT1
PTA19	GPIO	Green LED
PTA18	GPIO	Blue LED
PTB2	ADC	ADC0 channel 3
PTC2	I2C1_SCL	I2C / FXOS8700
PTC3	I2C1_SDA	I2C / FXOS8700
PTC4	GPIO	SW3
PTC5	GPIO	SW4
PTC6	LPUART0_RX	UART Console
PTC7	LPUART0_TX	UART Console
PTC16	SPI0_SCK	SPI
PTC17	SPI0_SOUT	SPI
PTC18	SPI0_SIN	SPI
PTC19	SPI0_PCS0	SPI

System Clock¶

The KW41Z SoC is configured to use the 32 MHz external oscillator on the board with the on-chip FLL to generate a 40 MHz system clock.

Serial Port¶

The KW41Z SoC has one UART, which is used for the console.

Programming and Debugging¶

Build and flash applications as usual (see Building an Application and Run an Application for more details).

Configuring a Debug Probe¶

A debug probe is used for both flashing and debugging the board. This board is configured by default to use the OpenSDA DAPLink Onboard Debug Probe.

Option 1: OpenSDA DAPLink Onboard Debug Probe (Recommended)¶

Install the pyOCD Debug Host Tools and make sure they are in your search path.

Follow the instructions in OpenSDA DAPLink Onboard Debug Probe to program the OpenSDA DAPLink FRDM-KW41Z Firmware.

Option 2: OpenSDA J-Link Onboard Debug Probe ¶

Install the J-Link Debug Host Tools and make sure they are in your search path.

Follow the instructions in OpenSDA J-Link Onboard Debug Probe to program the OpenSDA J-Link FRDM-KW41Z Firmware.

Add the arguments -DBOARD_FLASH_RUNNER=jlink and -DBOARD_DEBUG_RUNNER=jlink when you invoke west build to override the default runner from pyOCD to J-Link:

# From the root of the zephyr repository
west build -b frdm_kw41z samples/hello_world -- -DBOARD_FLASH_RUNNER=jlink -DBOARD_DEBUG_RUNNER=jlink

Configuring a Console¶

Regardless of your choice in debug probe, we will use the OpenSDA microcontroller as a usb-to-serial adapter for the serial console.

Connect a USB cable from your PC to J6.

Use the following settings with your serial terminal of choice (minicom, putty, etc.):

Speed: 115200
Data: 8 bits
Parity: None
Stop bits: 1

Flashing¶

Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b frdm_kw41z samples/hello_world
west flash

Open a serial terminal, reset the board (press the SW1 button), and you should see the following message in the terminal:

***** Booting Zephyr OS v1.14.0-rc1 *****
Hello World! frdm_kw41z

Debugging¶