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
FRDM-K22F

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
PTD4 SPI0_PCS1 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.

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

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 debug

Open a serial terminal, step through the application in your debugger, and you should see the following message in the terminal:

***** Booting Zephyr OS v2.0.0 *****
Hello World! frdm_k22f