'''
PIN13 - R1 (OUTPUT)
PIN14 - R2 (OUTPUT)
PIN15 - R3 (OUTPUT)
PIN16 - R4 (OUTPUT)

PIN32 - C1 (INPUT)
PIN33 - C2 (INPUT)
PIN34 - C3 (INPUT)
PIN35 - C4 (INPUT)
'''


'''
from machine import mem32
import time

GPIO_OUT_W1TS_REG       = 0x3FF44008
GPIO_OUT_W1TC_REG       = 0x3FF4400C
GPIO_ENABLE_REGISTER    = 0x3FF44020

GPIO5 = 5

mem32[GPIO_ENABLE_REGISTER] |= 1 << GPIO5

while True:
    mem32[GPIO_OUT_W1TS_REG] |= 1 << GPIO5
    print("LED ON")
    # delay
    time.sleep(1)
    
    mem32[GPIO_OUT_W1TC_REG] |= 1 << GPIO5
    print("LED OFF")
    #delay
    time.sleep(1)
'''
import machine
import time

# GPIO specifics for rows and columns
ROWS = [13, 14, 15, 16]
COLS = [32, 33, 34, 35]

# Register base addresses
GPIO_ENABLE_REG = 0x3FF44020  # GPIO direction register
GPIO_OUT_W1TS_REG = 0x3FF44008  # GPIO write 1 to set register
GPIO_OUT_W1TC_REG = 0x3FF4400C  # GPIO write 1 to clear register
GPIO_IN_REG = 0x3FF4403C  # GPIO input register
GPIO_PIN_BASE = 0x3FF44000  # Base for GPIO_PINn_REG

# Configure row pins as output
for row in ROWS:
    print(f"Configuring GPIO{row} as output.")
    machine.mem32[GPIO_ENABLE_REG] |= (1 << row)  # Set as output
    machine.mem32[GPIO_OUT_W1TC_REG] |= (1 << row)  # Initially set LOW

# Configure column pins as input with pull-up resistors using registers
for col in COLS:
    print(f"Configuring GPIO{col} as input with pull-up.")
    pin_reg = GPIO_PIN_BASE + (col * 0x04)  # Address of GPIO_PINn_REG
    machine.mem32[pin_reg] |= (1 << 2)  # Enable pull-up resistor

# Keypad layout (customize based on your keypad)
KEYPAD = [
    ['1', '2', '3', 'A'],
    ['4', '5', '6', 'B'],
    ['7', '8', '9', 'C'],
    ['*', '0', '#', 'D']
]

def scan_keypad():
    for row_idx, row_pin in enumerate(ROWS):
        # Activate the current row (set HIGH)
        print(f"Activating row GPIO{row_pin}.")
        machine.mem32[GPIO_OUT_W1TS_REG] = (1 << row_pin)

        # Read columns to detect keypress
        for col_idx, col_pin in enumerate(COLS):
            col_state = machine.mem32[GPIO_IN_REG] & (1 << col_pin)
            print(f"Checking column GPIO{col_pin}: {'HIGH' if col_state else 'LOW'}.")
            if not col_state:  # If column is LOW
                print(f"Key pressed: Row {row_idx}, Col {col_idx}.")
                # Deactivate the current row (set LOW)
                machine.mem32[GPIO_OUT_W1TC_REG] = (1 << row_pin)
                return KEYPAD[row_idx][col_idx]  # Return key pressed

        # Deactivate the current row (set LOW)
        print(f"Deactivating row GPIO{row_pin}.")
        machine.mem32[GPIO_OUT_W1TC_REG] = (1 << row_pin)

    return None  # No key pressed

# Main loop to read the keypad
while True:
    key = scan_keypad()
    if key:
        print(f"Key Pressed: {key}")
    else:
        print("No key pressed.")
    time.sleep(0.1)  # Small delay to debounce