archieve: homework7 header

homework7/src/homework7.h

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+/*
+ * @name: homework7.h
+ * @author: msksbr
+ * @date: 2025-05-24
+ * @description: a header for homework7's homework tests
+ * @version: 1.0
+ * variables:
+ *   1.0:
+ *     1. sbit DB_0 ~ sbit DB_7: pin number for led matrix cathodes
+ *     2. pin number for 74HC138's address pins & enable pin
+ *       2.1. sbit ADDR0 ~ sbit ADDR2: pin number for 74HC138's address pins
+ *       2.2. sbit ADDR3 & sbit ENLED: pin number for 74HC138's enable pin
+ * functions:
+ *   1.0:
+ *     1. void switch_138(unsigned char n): switch the 74HC138's address to n
+ *     2. void delay_ms(unsigned char ms): a timer by ms base on timer0 mode 1
+ */
+
+#include <REG52.H>
+
+// variables:
+// 1. sbit DB_0 ~ sbit DB_7: pin number for led matrix cathodes
+sbit DB_0 = P2 ^ 0;
+sbit DB_1 = P2 ^ 1;
+sbit DB_2 = P2 ^ 2;
+sbit DB_3 = P2 ^ 3;
+sbit DB_4 = P2 ^ 4;
+sbit DB_5 = P2 ^ 5;
+sbit DB_6 = P2 ^ 6;
+sbit DB_7 = P2 ^ 7;
+// 2. pin number for 74HC138's address pins & enable pin
+//  2.1. sbit ADDR0 ~ sbit ADDR2: pin number for 74HC138's address pins
+sbit ADDR0 = P1 ^ 0; // @var ADDR0: to A(A0)
+sbit ADDR1 = P2 ^ 1; // @var ADDR1: to B(A1)
+sbit ADDR2 = P2 ^ 2; // @var ADDR2: to C(A2)
+// 2.2. sbit ADDR3 & sbit ENLED: pin number for 74HC138's enable pin
+sbit ADDR3 = P2 ^ 3; // @var ADDR3: to E1
+sbit ENLED = P2 ^ 4; // @var ENLED: to E2 & E3
+
+// functions:
+// 1. void switch_138(unsigned char n): switch the 74HC138's address to n
+void switch_138(unsigned char n)
+{
+    // @subsection: enable the 74HC138
+    ENLED = 0;
+    ADDR3 = 1;
+    // @subsection: turn n to 3 bit binary number
+    bit A0 = n & 0x01;
+    bit A1 = (n >> 1) & 0x01;
+    bit A2 = (n >> 2) & 0x01;
+    // @subsection: switch the 74HC138's address to n
+    ADDR0 = A0;
+    ADDR1 = A1;
+    ADDR2 = A2;
+}
+// 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;
+    }
+}