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NXP FRDM-KL25Z

Overview

The Freedom KL25Z is an ultra-low-cost development platform for Kinetis® L Series KL1x (KL14/15) and KL2x (KL24/25) MCUs built on ARM® Cortex®-M0+ processor.

The FRDM-KL25Z features include easy access to MCU I/O, battery-ready, low-power operation, a standard-based form factor with expansion board options and a built-in debug interface for flash programming and run-control.

Hardware

MKL25Z128VLK4 MCU @ 48 MHz, 128 KB flash, 16 KB SRAM, USB OTG (FS), 80LQFP
On board capacitive touch “slider”, MMA8451Q accelerometer, and tri-color LED
OpenSDA debug interface

For more information about the KL25Z SoC and FRDM-KL25Z board:

Supported Features

The frdm_kl25z 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
UART	on-chip	serial port-polling; serial port-interrupt
I2C	on-chip	i2c
ADC	on-chip	adc
FLASH	on-chip	soc flash
USB	on-chip	USB device

The default configuration can be found in the defconfig file:

boards/arm/frdm_kl25z/frdm_kl25z_defconfig

Other hardware features are not currently supported by the port.

Connections and IOs

The KL25Z SoC has five pairs of pinmux/gpio controllers, and all are currently enabled (PORTA/GPIOA, PORTB/GPIOB, PORTC/GPIOC, PORTD/GPIOD, and PORTE/GPIOE) for the FRDM-KL25Z board.

Name	Function	Usage
PTB2	ADC	ADC0 channel 12
PTB18	GPIO	Red LED
PTB19	GPIO	Green LED
PTD1	GPIO	Blue LED
PTA1	UART0_RX	UART Console
PTA2	UART0_TX	UART Console
PTE24	I2C0_SCL	I2C
PTE25	I2C0_SDA	I2C

System Clock

The KL25Z SoC is configured to use the 8 MHz external oscillator on the board with the on-chip FLL to generate a 48 MHz system clock.

Serial Port

The KL25Z UART0 is used for the console.

USB

The KL25Z SoC has a USB OTG (USBOTG) controller that supports both device and host functions through its mini USB connector (USB KL25Z). 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Early versions of this board have an outdated version of the OpenSDA bootloader and require an update.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-KL25Z 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-KL25Z 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_kl25z 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 J7.

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_kl25z 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_kl25z

Debugging