Modify the diagram and code analysis

README.md

@@ -22,6 +22,9 @@ or an adept learner seeking to deepen your knowledge, this kit is tailored to me
 
 <a id="update"></a>
 ## Update:
+2023-09-22:
+- Modify the diagram and code analysis of 3.1_Reversing_Aid.
+
 2023-08-17:
  - Modify certain project content that requires libraries.
 

docs/source/arduino/3.1_Reversing_Aid.rst

@@ -56,20 +56,53 @@ Code
 Example Explanation
 ---------------------------
 
-In this project, we need to avoid the interference between the LCD
-screen and the alarm system as much as possible (for example, the LED
-flicker time is too long and the LCD refresh is delayed), so please
-avoid using the delay() statement and use two separate intervals to
-control the working frequency of the LCD and alarm system respectively.
-Its workflow is shown in the flow chart. For analysis of Interval
-function, refer to :ref:`ar_interval`.
-
-.. image:: img/Part_three_1_Example_Explanation.png
-   :align: center
+This code helps us create a simple distance measuring device that can measure the distance between objects and provide feedback through an LCD display and a buzzer.
 
-Phenomenon Picture
--------------------------
+The ``loop()`` function contains the main logic of the program and runs continuously. Let's take a closer look at the ``loop()`` function.
 
-.. image:: img/image267.jpeg
-   :align: center
+#. Loop to read distance and update parameters
+
+    In the ``loop``, the code first reads the distance measured by the ultrasonic module and updates the interval parameter based on the distance. 
+
+    .. code-block:: arduino
+
+        // Update the distance
+        distance = readDistance();
+
+        // Update intervals based on distance
+        if (distance <= 10) {
+            intervals = 300;
+        } else if (distance <= 20) {
+            intervals = 500;
+        } else if (distance <= 50) {
+            intervals = 1000;
+        } else {
+            intervals = 2000;
+        }
+
+#. Check if it's time to beep
+
+    The code calculates the difference between the current time and the previous beep time, and if the difference is greater than or equal to the interval time, it triggers the buzzer and updates the previous beep time.
+
+    .. code-block:: arduino
+
+        unsigned long currentMillis = millis();
+        if (currentMillis - previousMillis >= intervals) {
+            Serial.println("Beeping!");
+            beep();
+            previousMillis = currentMillis;
+        }
+
+#. Update LCD display
+
+    The code clears the LCD display and then displays "Dis:" and the current distance in centimeters on the first line.
+
+    .. code-block:: arduino
+
+        lcd.clear();
+        lcd.setCursor(0, 0);
+        lcd.print("Dis: ");
+        lcd.print(distance);
+        lcd.print(" cm");
 
+        delay(100);