3 files changed, 6 insertions, 100 deletions
diff --git a/components/drivers/hwtimer/README_CN.md b/components/drivers/hwtimer/README_CN.md
deleted file mode 100644
index 810b1b1d80..0000000000
--- a/components/drivers/hwtimer/README_CN.md
+++ /dev/null
@@ -1,97 +0,0 @@
-# 定时器设备
-
-## 功能
-
-* 时间测量
-* 周期或单次执行回调函数
-  
-## 编译
-
-1. 在rtconfig.h添加 `#define RT_USING_HWTIMER`
-
-## 使用流程
-
-1. 以读写方式打开设备
-2. 设置超时回调函数（如果需要）
-3. 根据需要设置定时模式（单次/周期）
-4. 设置计数频率（可选）
-5. 写入超时值，定时器随即启动
-6. 停止定时器（可选）
-7. 关闭设备（如果需要）
-
-应用参考 [hwtimer_test] (/examples/test/hwtimer\_test.c)
-
-## 驱动编写指南
-
-### 操作接口
-
-``` 
-struct rt_hwtimer_ops
-{
-    void (*init)(struct rt_hwtimer_device *timer, rt_uint32_t state);
-    rt_err_t (*start)(struct rt_hwtimer_device *timer, rt_uint32_t cnt, rt_hwtimer_mode_t mode);
-    void (*stop)(struct rt_hwtimer_device *timer);
-    rt_uint32_t (*count_get)(struct rt_hwtimer_device *timer);
-    rt_err_t (*control)(struct rt_hwtimer_device *timer, rt_uint32_t cmd, void *args);
-};
-```
-
-* init - state <1 打开设备 0 关闭设备> 
-* start - cnt <超时值> - mode <单次/周期>
-* stop - <停止计数>
-* count_get - <读取计数器值>
-* control - <设置计数频率 >
-
-### 定时器特征信息
-
-```
-struct rt_hwtimer_info
-{
-    rt_int32_t maxfreq;   
-    rt_int32_t minfreq;    
-    rt_uint32_t maxcnt;     
-    rt_uint8_t  cntmode;  
- };
-```
-
-* maxfreq <设备支持的最大计数频率>
-* minfreq <设备支持的最小计数频率>
-* maxcnt  <计数器最大计数值>
-* cntmode <递增计数/递减计数>
-  
-### 注册设备
-
-```
-static rt_hwtimer_t _timer0;
-int stm32_hwtimer_init(void)
-{
-    _timer0.info = &_info;
-    _timer0.ops  = &_ops;
-
-    rt_device_hwtimer_register(&_timer0, "timer0", TIM2);
-
-    return 0;
-}
-```
-
-### 定时器中断
-
-```
-void timer_irq_handler(void)
-{
-    //其它操作
-    
-    rt_device_hwtimer_isr(&_timer0);
-}
-```
-
-## 注意事项
-
-**可能出现定时误差**
-
-误差原因：
-
-假设计数器最大值0xFFFF，计数频率1Mhz，定时时间1秒又1微秒。
-
-由于定时器一次最多只能计时到65535us，对于1000001us的定时要求。
-可以50000us定时20次完成，此时将会出现计算误差1us。
diff --git a/components/drivers/hwtimer/hwtimer.c b/components/drivers/hwtimer/hwtimer.c
index c1a7b75ecc..73a467fabb 100644
--- a/components/drivers/hwtimer/hwtimer.c
+++ b/components/drivers/hwtimer/hwtimer.c
@@ -8,10 +8,13 @@
  * 2015-08-31     heyuanjie87    first version
  */
 
-#include <rtthread.h>
 #include <rtdevice.h>
 #include <rthw.h>
 
+#define DBG_TAG "hwtimer"
+#define DBG_LVL DBG_INFO
+#include <rtdbg.h>
+
 rt_inline rt_uint32_t timeout_calc(rt_hwtimer_t *timer, rt_hwtimerval_t *tv)
 {
     float overflow;
@@ -234,7 +237,8 @@ static rt_err_t rt_hwtimer_control(struct rt_device *dev, int cmd, void *args)
         f = (rt_uint32_t*)args;
         if ((*f > timer->info->maxfreq) || (*f < timer->info->minfreq))
         {
-            result = -RT_ERROR;
+            LOG_W("frequency setting out of range! It will maintain at %d Hz", timer->freq);
+            result = -RT_EINVAL;
             break;
         }
 
diff --git a/components/drivers/misc/dac.c b/components/drivers/misc/dac.c
index ecbadfd502..c1176cc36c 100644
--- a/components/drivers/misc/dac.c
+++ b/components/drivers/misc/dac.c
@@ -8,7 +8,6 @@
  * 2020-06-19     thread-liu   the first version
  */
 
-#include <rtthread.h>
 #include <rtdevice.h>
 
 #include <string.h>