Hexiwear

Overview

Hexiwear is powered by a Kinetis K64 microcontroller based on the ARM Cortex-M4 core. Another Kinetis wireless MCU, the KW40Z, provides Bluetooth Low Energy connectivity. Hexiwear also integrates a wide variety of sensors, as well as a user interface consisting of a 1.1” 96px x 96px full color OLED display and six capacitive buttons with haptic feedback.

  • Eye-catching Smart Watch form factor with powerful, low power Kinetis K6x MCU and 6 on-board sensors.
  • Designed for wearable applications with the onboard rechargeable battery, OLED screen and onboard sensors such as optical heart rate, accelerometer, magnetometer and gyroscope.
  • Designed for IoT end node applications with the onboard sensor’s such as temperature, pressure, humidity and ambient light.
  • Flexibility to let you add the sensors of your choice nearly 200 additional sensors through click boards.
Hexiwear

Hardware

  • Main MCU: NXP Kinetis K64x (ARM Cortex-M4, 120 MHz, 1M Flash, 256K SRAM)
  • Wireless MCU: NXP Kinetis KW4x (ARM Cortex-M0+, Bluetooth Low Energy & 802.15.4 radio)
  • 6-axis combo Accelerometer and Magnetometer NXP FXOS8700
  • 3-Axis Gyroscope: NXP FXAS21002
  • Absolute Pressure sensor NXP MPL3115
  • Li-Ion/Li-Po Battery Charger NXP MC34671
  • Optical heart rate sensor Maxim MAX30101
  • Ambient Light sensor, Humidity and Temperature sensor
  • 1.1” full color OLED display
  • Haptic feedback engine
  • 190 mAh 2C Li-Po battery
  • Capacitive touch interface
  • RGB LED

For more information about the K64F SoC and Hexiwear board:

Supported Features

The hexiwear_k64 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
I2C on-chip i2c
WATCHDOG on-chip watchdog
ADC on-chip adc
PWM on-chip pwm
UART on-chip serial port-polling; serial port-interrupt
FLASH on-chip soc flash
SENSOR off-chip fxos8700 polling; fxos8700 trigger; fxas21002 polling; fxas21002 trigger; max30101 polling

The default configuration can be found in the defconfig file:

boards/arm/hexiwear_k64/hexiwear_k64_defconfig

Other hardware features are not currently supported by the port.

Connections and IOs

The K64F SoC has five pairs of pinmux/gpio controllers.

Name Function Usage
PTA29 GPIO LDO_EN
PTB0 I2C0_SCL I2C / MAX30101
PTB1 I2C0_SDA I2C / MAX30101
PTB12 GPIO 3V3B EN
PTB16 UART0_RX UART Console
PTB17 UART0_TX UART Console
PTC8 GPIO / PWM Red LED
PTC9 GPIO / PWM Green LED
PTC10 I2C1_SCL I2C / FXOS8700 / FXAS21002
PTC11 I2C1_SDA I2C / FXOS8700 / FXAS21002
PTC14 GPIO Battery sense enable
PTC18 GPIO FXAS21002 INT2
PTD0 GPIO / PWM Blue LED
PTD13 GPIO FXOS8700 INT2
PTE24 UART4_RX UART BT HCI
PTE25 UART4_TX UART BT HCI

System Clock

The K64F SoC is configured to use the 12 MHz external oscillator on the board with the on-chip PLL to generate a 120 MHz system clock.

Serial Port

The K64F SoC has six UARTs. One is configured for the console, another for BT HCI, and the remaining are not used.

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 the default for this board, therefore it is not necessary to set OPENSDA_FW=daplink explicitly when using the default flash and debug mechanisms.

With these mechanisms, applications for the hexiwear_k64 board configuration can be built and flashed in the usual way (see Build an Application and Run an Application for more details).

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 not the default for this board, therefore it is necessary to set OPENSDA_FW=jlink explicitly in the environment before programming and debugging.

Note

The OpenSDA adapter is shared between the K64 and the KW40Z via switches, therefore only one SoC can be flashed, debugged, or have an open console at a time.

Configure the docking station switches to route the desired SoC signals to the OpenSDA adapter:

Switch Signal KW40Z K64
1 MK64 SWDIO OFF ON
2 MK64 RST OFF ON
3 MKW40 RST ON OFF
4 MKW40 SWDIO ON OFF
5 OSDA ON ON
6 LED1 OFF OFF
7 LED2 OFF OFF
8 LED3 OFF OFF

Flashing

This example uses the Hello World sample with the pyOCD tools.

# 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_k64 ..

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

Open a serial terminal (minicom, putty, etc.) with the following settings:

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

Reset the board and you should be able to see on the corresponding Serial Port the following message:

Hello World! arm

Debugging

You can debug an application in the usual way. Here is an example for the Hello World application.

# On Linux/macOS
cd $ZEPHYR_BASE/samples/hello_world
# If you already made a build directory (build) and ran cmake, just 'cd build' instead.
mkdir build && cd build

# On Windows
cd %ZEPHYR_BASE%\samples\hello_world
# If you already made a build directory (build) and ran cmake, just 'cd build' instead.
mkdir build & cd build

# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=hexiwear_k64 ..

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

Using Bluetooth

Configure the KW40Z as a Bluetooth controller

The K64 can support Zephyr Bluetooth host applications when you configure the KW40Z as a Bluetooth controller.

  1. Download and install the KW40Z Connectivity Software. This package contains Bluetooth controller application for the KW40Z.
  2. Flash the file tools/binaries/BLE_HCI_Modem.bin to the KW40Z.

Now you can build and run the sample Zephyr Bluetooth host applications on the K64. You do not need to repeat this step each time you flash a new Bluetooth host application to the K64.

Peripheral Heart Rate Sensor

Navigate to the Zephyr samples/bluetooth/peripheral_hr sample application, then build and flash it to the Hexiwear K64. Make sure the OpenSDA switches on the docking station are configured for the K64.

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

# On Windows
cd %ZEPHYR_BASE%\samples\bluetooth\peripheral_hr
mkdir build & cd build

# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=hexiwear_k64 ..

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

Reset the KW40Z and the K64 using the push buttons on the docking station.

Install the Kinetis BLE Toolbox on your smartphone:

Open the app, tap the Heart Rate feature, and you should see a Zephyr Heartrate Sensor device. Tap the Zephyr Heartrate Sensor device and you will then see a plot of the heart rate data that updates once per second.