From f9d3b94f6317d9d7d6f26550aed29f35eea2bd07 Mon Sep 17 00:00:00 2001
From: EN <none>
Date: Thu, 11 Jul 2024 18:14:13 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E8=B6=85=E5=A3=B0=E6=B3=A2?=
 =?UTF-8?q?=EF=BC=8C=E7=AE=97=E6=B3=95=E9=9C=80=E8=A6=81=E4=BF=AE=E6=94=B9?=
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---
 Core/Inc/hcsr04.h |  9 +++++
 Core/Src/hcsr04.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 Core/Inc/hcsr04.h
 create mode 100644 Core/Src/hcsr04.c

diff --git a/Core/Inc/hcsr04.h b/Core/Inc/hcsr04.h
new file mode 100644
index 0000000..9c00c39
--- /dev/null
+++ b/Core/Inc/hcsr04.h
@@ -0,0 +1,9 @@
+#ifndef __HCSR04_H
+#define __HCSR04_H
+
+#include "main.h"
+
+int16_t sonar_mm(void);
+float sonar(void);
+
+#endif
diff --git a/Core/Src/hcsr04.c b/Core/Src/hcsr04.c
new file mode 100644
index 0000000..aa57595
--- /dev/null
+++ b/Core/Src/hcsr04.c
@@ -0,0 +1,85 @@
+#include "hcsr04.h"
+#include "tim.h"
+
+// time 的单位是 μs
+uint64_t time;     // 声明变量，用来计时
+uint64_t time_end; // 声明变量，存储回波信号时间
+uint8_t state = 1;
+
+// HACK 临时的 delay 解决方法
+void delay_us(uint16_t us);
+
+int16_t sonar_mm(void) // 测距并返回单位为毫米的距离结果
+{
+    uint32_t distance, distance_mm = 0;
+    HAL_GPIO_WritePin(SCL_C_GPIO_Port, SCL_C_Pin, GPIO_PIN_SET);   // 输出高电平
+    delay_us(15);                                                  // 延时15微秒
+    HAL_GPIO_WritePin(SCL_C_GPIO_Port, SCL_C_Pin, GPIO_PIN_RESET); // 输出低电平
+
+    while (state)
+        ;
+    state = 1;
+
+    // BUG 现在 time 的单位是 1μs
+    if (time_end / 100 < 38) // 判断是否小于38毫秒，大于38毫秒的就是超时，直接调到下面返回0
+    {
+        distance = (time_end * 346) / 2; // 计算距离，25°C空气中的音速为346m/s
+        distance_mm = distance / 100;    // 因为上面的time_end的单位是10微秒，所以要得出单位为毫米的距离结果，还得除以100
+    }
+    return distance_mm; // 返回测距结果
+}
+
+float sonar(void) // 测距并返回单位为米的距离结果
+{
+    uint32_t distance, distance_mm = 0;
+    float distance_m = 0;
+    HAL_GPIO_WritePin(SCL_C_GPIO_Port, SCL_C_Pin, GPIO_PIN_SET);   // 输出高电平
+    delay_us(15);                                                  // 延时15微秒
+    HAL_GPIO_WritePin(SCL_C_GPIO_Port, SCL_C_Pin, GPIO_PIN_RESET); // 输出低电平
+    
+    while (state)
+        ;
+    state = 1;
+
+    // BUG 现在 time 的单位是 1μs
+    if (time_end / 100 < 38)
+    {
+        distance = (time_end * 346) / 2;
+        distance_mm = distance / 100;
+        distance_m = distance_mm / 1000;
+    }
+    return distance_m;
+}
+
+void delay_us(uint16_t us)
+{
+    HAL_TIM_Base_Start_IT(&htim2);
+    time = 0;
+    while (time < us)
+        ;
+    HAL_TIM_Base_Stop_IT(&htim2);
+}
+
+void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
+{
+    if (htim == &htim2)
+        ++time;
+}
+
+void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
+{
+    if (GPIO_Pin == SDA_C_EXTI12_Pin)
+    {
+        if (HAL_GPIO_ReadPin(SDA_C_EXTI12_GPIO_Port, SDA_C_EXTI12_Pin))
+        {
+            HAL_TIM_Base_Start_IT(&htim2);
+            time = 0;
+        }
+        else
+        {
+            time_end = time;
+            HAL_TIM_Base_Stop_IT(&htim2);
+            state = 0;
+        }
+    }
+}