Erich of MCUonEclipse writes: The Freescale FRDM boards are using a Kinetis K20 based circuit (see “OpenSDA on the Freedom KL25Z Board“): However, that firmware is not open: the K20 is secured and protected, so the firmware cannot be changed. Newer Freescale FRDM boards like FRDM-K22F2 and FRDM-K64F do have an open source bootloader and debug […]