RaspberryPiCodeOrganKeyboard61note/4x4keypad.py at main · thejonathanjin/RaspberryPiCodeOrganKeyboard61note · GitHub

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import RPi.GPIO as GPIO
import time

# GPIO Pin Setup (BCM Numbering)

# ~ ROW_PINS = [2, 3, 4, 17, 27, 22]    # 6 rows - outputs, change to your wiring
# ~ COL_PINS = [10, 9, 11, 5, 6, 13, 19, 26, 21, 20, 16] # 11 cols - inputs with pull-up

# ~ ROWS = [25, 8, 7, 1]
# ~ COLS = [12, 16, 20, 21]

ROWS = [2, 3, 4, 17] # ROWS are INPUT(S) x4
COLS = [10, 9, 11, 5] # COLS are OUTPUT(S) x4

# Keypad Layout
KEYS = [
    ['1', '2', '3', 'A'],
    ['4', '5', '6', 'B'],
    ['7', '8', '9', 'C'],
    ['*', '0', '#', 'D']
]

# def setup():
#     GPIO.setmode(GPIO.BCM)
#     # Set rows as outputs, initialized to LOW
#     for r in ROWS:
#         GPIO.setup(r, GPIO.OUT)
#         GPIO.output(r, GPIO.LOW)
#     # Set columns as inputs with internal pull-down resistors
#     for c in COLS:
#         GPIO.setup(c, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

def setup():
    GPIO.setmode(GPIO.BCM)
    # Set cols as outputs, initialized to LOW
    for c in COLS:
        GPIO.setup(c, GPIO.OUT)
        GPIO.output(c, GPIO.LOW)
    # Set rows as inputs with internal pull-up resistors
    for r in ROWS:
        GPIO.setup(r, GPIO.IN, pull_up_down=GPIO.PUD_UP) # comment by JT "should this be PUD_UP instead of DOWN?"

# def scan_keypad():
#     for row_idx, row_pin in enumerate(ROWS):
#         # Send a HIGH pulse to the current row
#         GPIO.output(row_pin, GPIO.HIGH)
#         for col_idx, col_pin in enumerate(COLS):
#             # Check if any column in this row is now HIGH
#             if GPIO.input(col_pin) == GPIO.HIGH:
#                 key = KEYS[row_idx][col_idx]
#                 print(f"Key Pressed: {key}")
#                 # Wait until button is released to avoid double-triggers
#                 while GPIO.input(col_pin) == GPIO.HIGH:
#                     time.sleep(0.05)
#                 GPIO.output(row_pin, GPIO.LOW)
#                 return key
#         # Reset row to LOW before moving to next
#         GPIO.output(row_pin, GPIO.LOW)
#     return None

# same code block as above, except ROWS is swapped with COLS, vice versa;
# row_pin, col_pin variables swapped
# row_idx, col_idx variables swapped

def scan_keypad():
    for col_idx, col_pin in enumerate(COLS):
        # Send a HIGH pulse to the current row
        GPIO.output(col_pin, GPIO.HIGH)

        for row_idx, row_pin in enumerate(ROWS):
            # Check if any column in this row is now HIGH
            if GPIO.input(row_pin) == GPIO.HIGH:
                key = KEYS[col_idx][row_idx]
                print(f"Key Pressed: {key}")
                # Wait until button is released to avoid double-triggers
                while GPIO.input(row_pin) == GPIO.HIGH:
                    time.sleep(0.05)
                GPIO.output(col_pin, GPIO.LOW)
                return key
        # Reset row to LOW before moving to next
        GPIO.output(col_pin, GPIO.LOW)
    return None

try:
    setup()
    print("Keypad scanner active. Press CTRL+C to exit.")
    while True:
        scan_keypad()
        time.sleep(0.1)  # Polling interval
except KeyboardInterrupt:
    GPIO.cleanup()