MINI USB PORT DEVELOPMENT BOARDS
Teensy USB Development Board

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entry-level Mini-USB kit form PJRC for $19 (not including shipping). The Teensy USB Development Board is a complete USB-based micro-controller development system. Version 3.0 features a 32-bit ARM processor

FRDM-KL25Z: Freescale Freedom Development Platform for Kinetis KL1x and KL2x MCUs 

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The FRDM-KL25Z is an ultra-low-cost development platform enabled by Kinetis L Series KL1x and KL2x MCUs families built on ARM® Cortex™-M0+ processor. 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. The FRDM-KL25Z is supported by a range of Freescale and third-party development software.