finish the CMSIS_RTOS_API_Use_Guide document

doc/23.CMSIS_RTOS_API_Use_Guide.md

@@ -731,7 +731,88 @@ task1 finish do sth!
 task2 get mutex,doing sth...
 ```
 ## 3.5. 动态内存使用示例
+```c
+#include <cmsis_os.h>
+
+typedef struct blk_st {
+    int   id;
+    char* payload;
+} blk_t;
+
+#define MMBLK_BLK_NUM 10
+
+osPoolDef (MemPool, MMBLK_BLK_NUM, blk_t);
+osPoolId mem_pool_id;
 
+void task1_entry(void *arg)
+{   
+    
+    blk_t *ptr = NULL;
+    osStatus err;
+    
+    /* 打印出一个块的大小 */
+    printf("block size is %d bytes\r\n", sizeof(blk_t));
+    
+    /* 申请一个块 */
+    ptr = osPoolAlloc(mem_pool_id);
+    if (ptr == NULL) {
+        printf("a mmblk alloc fail\r\n");
+        return;
+    }
+    else {
+        printf("a mmblk alloc success\r\n");
+    }
+    
+    /* 使用该块 */
+    ptr->id = 1;
+    ptr->payload = "hello";
+    printf("mmblk id:%d payload:%s\r\n", ptr->id, ptr->payload);
+    
+    /* 使用完毕之后释放 */
+    err = osPoolFree(mem_pool_id, ptr);
+    if (err != osOK) {
+        printf("a mmblk free fail, err = %d\r\n", err);
+        return;
+    }
+    else {
+        printf("a mmblk free success\r\n");
+    }
+    
+    while (1) {
+        tos_task_delay(1000);
+    }
+}
+
+#define STK_SIZE_TASK1      1024
+osThreadDef(task1_entry, osPriorityNormal, 1, STK_SIZE_TASK1);
+
+void application_entry(void *arg)
+{
+    //初始化静态内存池
+    mem_pool_id = osPoolCreate(osPool(MemPool));
+    if (mem_pool_id == NULL) {
+        printf("mmblk pool create fail\r\n");
+        return;
+    }
+    else {
+        printf("mmblk pool create success\r\n");
+    }
+
+    //创建任务
+    osThreadCreate(osThread(task1_entry), NULL);
+
+    return;
+}
+```
+运行结果为：
+```
+item size = 8 bytes, create ret = 0
+mmblk pool create success
+block size is 8 bytes
+a mmblk alloc success
+mmblk id:1 payload:hello
+a mmblk free success
+```
 
 ## 3.6. 消息队列使用示例
 ```c