STM32的编码器驱动存在计算问题

发布于 2023-06-08 11:10:43 浏览：840 订阅该版

文件 drv_pulse_encoder.c 中
```
rt_int32_t pulse_encoder_get_count(struct rt_pulse_encoder_device *pulse_encoder)
{
    struct stm32_pulse_encoder_device *stm32_device;
    stm32_device = (struct stm32_pulse_encoder_device*)pulse_encoder;
    return (rt_int32_t)((rt_int16_t)__HAL_TIM_GET_COUNTER(&stm32_device->tim_handler) + stm32_device->over_under_flowcount * AUTO_RELOAD_VALUE);
}
```
对编码器数值的计算可能存在问题：
```
(rt_int32_t)((rt_int16_t)__HAL_TIM_GET_COUNTER(&stm32_device->tim_handler) + stm32_device->over_under_flowcount * AUTO_RELOAD_VALUE);
```
其中`AUTO_RELOAD_VALUE`为重装载值:0x7FFF， 作为乘数应当+1

测试：
```
rt_device_read(dev, 0, (void *)&pulse_value, 1);
```

当over计数为0时正常：
![screenshot_图片.png](https://oss-club.rt-thread.org/uploads/20230608/70bf343d747007f6be49e5ee980289f6.png)

正常：
![screenshot_图片.png](https://oss-club.rt-thread.org/uploads/20230608/3a736b90ac1e818e1c8592b4158ed449.png)

非0时错误：
![screenshot_图片.png](https://oss-club.rt-thread.org/uploads/20230608/25cec97412d6ec517c6accb687b20ca7.png)
（结果应该为-1）

正常：
![screenshot_图片.png](https://oss-club.rt-thread.org/uploads/20230608/273fa8f1f381eec49d92ee028744b4f2.png)

错误：
![screenshot_图片.png](https://oss-club.rt-thread.org/uploads/20230608/ab73dd73813cc68e8060af45e403ba7e.png)
（结果应当为32768）