Erich Styger from MCU on Eclipse writes, “In this article I show the basic steps to get MQTT running on the NXP FRDM-K64F board using MCUXpresso IDE, lwip and MQTT. lwip ois a small and open source TCP/IP stack which is widely used. To keep things very simple in this first post, I’m using it in bare-metal (no RTOS) mode with no encryption/security. The principle applies to any IDE/toolchain, as long there is a lwip port available for your board and IDE/toolchain. I’m using the MCUXpresso IDE as it nicely integrates with the MCUXpresso SDK which includes a lwip port for the FRDM-K64F.”
More details at MCU on Eclipse homepage.