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-K22F¶

Overview¶

The Freedom-K22F is an ultra-low-cost development platform for Kinetis K22 MCUs.

Form-factor compatible with the Arduino R3 pin layout
Peripherals enable rapid prototyping, including a 6-axis digital accelerometer and magnetometer to create full eCompass capabilities, a tri-colored LED and 2 user push-buttons for direct interaction, a optional microSD card slot, and headers for use with Bluetooth* and 2.4 GHz radio add-on modules
OpenSDAv2, the NXP open source hardware embedded serial and debug adapter running an open source bootloader, offers options for serial communication, flash programming, and run-control debugging

Hardware¶

MK22FN512VLH12 (120 MHz, 1 MB flash memory, 256 KB RAM, low-power, crystal-less USB, and 64 pin Low profile Quad Flat Package (LQFP))
Dual role USB interface with micro-B USB connector
RGB LED
FXOS8700CQ accelerometer and magnetometer
Two user push buttons
Flexible power supply option - OpenSDAv2 USB, Kinetis K22 USB, and external source
Easy access to MCU input/output through Arduino* R3 compatible I/O connectors
Programmable OpenSDAv2 debug circuit supporting the CMSIS-DAP Interface software that provides:
- Mass storage device (MSD) flash programming interface
- CMSIS-DAP debug interface over a driver-less USB HID connection providing run-control debugging and compatibility with IDE tools
- Virtual serial port interface
- Open source CMSIS-DAP software project
Optional SDHC

For more information about the K22F SoC and FRDM-K22F board:

Supported Features¶

The frdm_k22f 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
SPI	on-chip	spi
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
USB	on-chip	USB device
SENSOR	off-chip	fxos8700 polling; fxos8700 trigger

The default configuration can be found in the defconfig file:

boards/arm/frdm_k22f/frdm_k22f_defconfig

Other hardware features are not currently supported by the port.

Connections and IOs¶

The K22F SoC has five pairs of pinmux/gpio controllers.

Name	Function	Usage
PTA1	GPIO	Red LED
PTA2	GPIO	Green LED
PTD5	GPIO	Blue LED
PTC1	GPIO	SW2
PTD0	GPIO	FXOS8700 INT1
PTD1	GPIO	FXOS8700 INT2
PTB17	GPIO	SW3
PTE1	UART1_RX	UART Console
PTE0	UART1_TX	UART Console
PTD2	UART2_RX	UART BT HCI
PTD3	UART2_TX	UART BT HCI
PTC4	SPI0_PCS0	SPI
PTD1	SPI0_SCK	SPI
PTD2	SPI0_SOUT	SPI
PTD3	SPI0_SIN	SPI
PTB2	I2C0_SCL	I2C / FXOS8700
PTB3	I2C0_SDA	I2C / FXOS8700

System Clock¶

The K22F SoC is configured to use the 8 MHz crystal oscillator on the board with the on-chip PLL to generate a 72 MHz system clock in its RUN mode. This clock was selected to allow for the maximum number of peripherals to be used with the crystal and PLL clocks. Other clock configurations are possible through NXP SDK currently.

Serial Port¶

The K22F SoC has three UARTs. One is configured for the console, another for BT HCI, and the remaining are not used.

USB¶

The K22F SoC has a USB OTG (USBOTG) controller that supports both device and host functions through its micro USB connector (K22F USB). Only USB device function is supported in Zephyr at the moment.

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.

Early versions of this board have an outdated version of the OpenSDA bootloader and require an update. Please see the DAPLink Bootloader Update page for instructions to update from the CMSIS-DAP bootloader to the DAPLink bootloader.

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-K22F 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 Segger J-Link OpenSDA V2.1 Firmware. Note that Segger does provide an OpenSDA J-Link Board-Specific Firmware for this board, however it is not compatible with the DAPLink bootloader.

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_k22f 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 J26.

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_k22f 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 v2.0.0 *****
Hello World! frdm_k22f

Debugging¶