Freescale-Kinetis-K21-50-MHz-MCU-Tower-System-Module-Freescale-TWR-K21D50M-The-TWR-K21D50M-microcontroller-module-is-designed-to-work-either-in-standalone-mode-or-as-part-of-the-Freescale-Tower-System-a-modular-development-platform-that-enables-rapid-prototyping-&-tool-re-use-through-reconfigurable-hardware-The-TWR-K21D50M-features-a-Tower-compatible-microcontroller-module-low-power-MK21DN512VMC5-MCU-at-50-MHz-with-512-KB-Flash-&-64-KB-RAM-in-a-MAPBGA-121-package-It-offers-a-Dual-role