archieve: homework7 test2

2025-05-25 00:13:04 +08:00
parent 1b64a5df5b
commit 3b682e993c
4 changed files with 58 additions and 12 deletions
@@ -57,15 +57,21 @@ void switch_138(unsigned char n)
 // 2. void delay_ms(unsigned char ms): a timer by ms base on timer0 mode 1
 void delay_ms(unsigned char ms)
 {
-    unsigned char i;
-    TMOD &= 0xF0;
-    TMOD |= 0x01;
-    for (i = 0; i < ms; i++) {
-        TH0 = 0xFC;
-        TL0 = 0x18;
-        TR0 = 1;
-        while (!TF0);
-        TR0 = 0;
-        TF0 = 0;
+    TMOD &= 0xF0; // set the timer mode to 16-bit timer mode.
+    TMOD |= 0x01; // set the timer mode to 16-bit timer mode.
+
+    // 1ms timer definition:
+    TH0 = 0XFC;
+    TL0 = 0X18;
+
+    // start the timer:
+    TR0 = 1;
+
+    while (ms--) {
+        while (!TF0) {} // wait for the timer to overflow.
+        TF0 = 0;        // clear the timer flag.
+        TH0 = 0XFC;     // reload the timer value.
+        TL0 = 0X18;     // reload the timer value.
    }
+    TR0 = 0; // stop the timer.
 }