Keypad-Synchronized Multi-Digit 7-Segment Display Using Arduino Nano

1#include <Keypad.h>
2
3/* ===== Keypad setup ===== */
4const byte ROWS = 4;
5const byte COLS = 4;
6
7char keys[ROWS][COLS] = {
8  {'1','2','3','A'},
9  {'4','5','6','B'},
10  {'7','8','9','C'},
11  {'*','0','#','D'}
12};
13
14byte rowPins[ROWS] = {9, 8, 7, 6};   // Connect to keypad ROW pins
15byte colPins[COLS] = {5, 4, 3, 2};   // Connect to keypad COL pins
16
17Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
18
19/* ===== 7-segment pins (a–g) ===== */
20int segA = 10;
21int segB = 11;
22int segC = 12;
23int segD = A0;
24int segE = A1;
25int segF = A2;
26int segG = A3;
27
28/* ===== Segment patterns for numbers 0–9 ===== */
29/* Common Cathode (HIGH = ON) */
30byte digits[10][7] = {
31  {1,1,1,1,1,1,0}, // 0
32  {0,1,1,0,0,0,0}, // 1
33  {1,1,0,1,1,0,1}, // 2
34  {1,1,1,1,0,0,1}, // 3
35  {0,1,1,0,0,1,1}, // 4
36  {1,0,1,1,0,1,1}, // 5
37  {1,0,1,1,1,1,1}, // 6
38  {1,1,1,0,0,0,0}, // 7
39  {1,1,1,1,1,1,1}, // 8
40  {1,1,1,1,0,1,1}  // 9
41};
42
43int segmentPins[7] = {segA, segB, segC, segD, segE, segF, segG};
44
45void setup() {
46  for (int i = 0; i < 7; i++) {
47    pinMode(segmentPins[i], OUTPUT);
48    digitalWrite(segmentPins[i], LOW);
49  }
50}
51
52void loop() {
53  char key = keypad.getKey();
54
55  if (key >= '0' && key <= '9') {
56    displayDigit(key - '0');
57  }
58}
59
60/* ===== Display function ===== */
61void displayDigit(int num) {
62  for (int i = 0; i < 7; i++) {
63    digitalWrite(segmentPins[i], digits[num][i]);
64  }
65}