FreeRTOS 7.1.1 发布，改进内容：
- The Cortex-M3 Tasking port was added.
- The separately distributed ports for Cortex-M0 IAR, Cortex-M0 GCC, and Cortex-M4F GCC were merged in.
- The Windows simulator was fixed to reduce usage of trace macros.
- A new trace macro was added, traceMOVE_TASK_TO_READY_STATE().
- The FreeRTOS MPU port was updated.
- The xQueueReset() and xSemaphoreGetMutexHolder() functions were introduced.
FreeRTOS是一个迷你操作系统内核的小型嵌入式系统。作为一个轻量级的操作系统，功能包括：任务管理、时间管理、信号量、消息队列、内存管理、记录功能等，可基本满足较小系统的需要。
