Hexiwear KW40Z


See Hexiwear for a general overview of the Hexiwear board and the main application SoC, the K64. The KW40Z is a secondary SoC on the board that provides wireless connectivity with a multimode BLE and 802.15.4 radio.

For more information about the KW40Z SoC:

Supported Features

The hexiwear_kw40z 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
GPIO on-chip gpio
ADC on-chip adc
UART on-chip serial port-polling; serial port-interrupt
RTT on-chip console
FLASH on-chip soc flash

The default configuration can be found in the defconfig file:


Other hardware features are not currently supported by the port.

Connections and IOs

The KW40Z SoC has three pairs of pinmux/gpio controllers, but only one is currently enabled (PORTC/GPIOC) for the hexiwear_kw40z board.

Name Function Usage
PTB1 ADC ADC0 channel 1

System Clock

The KW40Z 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 KW40Z SoC has one UART, which is used for BT HCI. The console is available using Segger RTT.

Programming and Debugging

The Hexiwear docking station includes the NXP OpenSDA serial and debug adapter built into the board to provide debugging, flash programming, and serial communication over USB.

To use the pyOCD tools with OpenSDA, follow the instructions in the pyOCD page using the DAPLink Hexiwear Firmware. The pyOCD tools are not the default for this board, therefore it is necessary to set OPENSDA_FW=daplink explicitly in the environment when programming and debugging.

To use the Segger J-Link tools with OpenSDA, follow the instructions in the Segger J-Link page using the Segger J-Link OpenSDA V2.1 Firmware. The Segger J-Link tools are the default for this board, therefore it is not necessary to set OPENSDA_FW=jlink explicitly when using the usual programming and debugging mechanisms.

With these mechanisms, applications for the hexiwear_kw40z board configuration can be built and flashed in the usual way (see Build an Application and Run an Application for more details).

Because Segger RTT is required for a console to KW40Z, the J-Link tools are recommended.


The Segger J-Link firmware does not support command line flashing, therefore the usual flash build target is not supported.


This example uses the Hello World sample with the Segger J-Link tools. This builds the Zephyr application, invokes the J-Link GDB server, attaches a GDB client, and programs the application to flash. It will leave you at a gdb prompt.

# On Linux/macOS
cd $ZEPHYR_BASE/samples/hello_world
mkdir build && cd build

# On Windows
cd %ZEPHYR_BASE%\samples\hello_world
mkdir build & cd build

# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=hexiwear_kw40z ..

# Now run ninja on the generated build system:
ninja debug

In a second terminal, open telnet:

$ telnet localhost 19021
Connected to localhost.
Escape character is '^]'.
SEGGER J-Link V6.14b - Real time terminal output
J-Link OpenSDA 2 compiled Feb 28 2017 19:27:57 V1.0, SN=621000000
Process: JLinkGDBServer

Continue program execution in GDB, then in the telnet terminal you should see:

***** BOOTING ZEPHYR OS v1.7.99 - BUILD: Apr  6 2017 21:09:52 *****
Hello World! arm