Printk to console fails for freescale kinetis 8.2.0 (Zephyr 2.6.0) on FRDM-K64F

Problem Description
Printk outputs are not sent to the console using Freescale Kinetis 8.2.0, Zephyr 2.6.0, PlatformIO Core 5.20 (Home 3.3.4). Platform is FRDM-K64F.

To Reproduce

  1. Install most recent PlatformIO v.2.3.3 in VS Studio Code (Core 5.2.0, Home 3.3.4).
  2. Install Platfrom “Freescale Kinetis”, ver. 8.2.0
  3. Try a blinky App and additionally add one line of code at the beginning of main:
    printk(“hello world! %s\n”, CONFIG_BOARD);
  4. prj.conf looks like
  5. build and upload to FRDM-K64F

Expected behavior
Green LED should start blinking, “hello world! …” should be seen in console .
Received behavior
The green LED is blinking only if CONFIG_SERIAL=n. LED is not blinking if CONFIG_SERIAL=y, printk statements are sent to console in no case.

Using the FRDM-K64F controller with the same simple application (blinky + “HelloWorld”) is working with Freescale Kinetis 8.1.0, Zephyr 2.5.0. LED is blinking properly, printk statements are sent to the console.

Without logging statements to the console application development is more complicated.

console output
No output.


  • OS: Windows 10
  • PlatformIO v.2.3.3 (Core 5.2.0), Zephyr 2.6.0, Freescale Kinetis 8.2.0
  • FRDM-K64F

Problem printk to console fails for freescale kinetis 8.2.0 (Zephyr 2.6.0) on FRDM-K64F · Issue #38631 · zephyrproject-rtos/zephyr (
was closed with the note to file this problem in this community.

That’s a clear bug report, please file it in Issues · platformio/platform-freescalekinetis · GitHub, not the community forum.