from machine import Pin
import time

## LCD Pins
# Control pins
rs = Pin(2, Pin.OUT)
rw = Pin(3, Pin.OUT)
en = Pin(4, Pin.OUT)

# Data pins D4–D7
# Data pins D4–D7
d4 = Pin(5, Pin.OUT)
d5 = Pin(6, Pin.OUT)
d6 = Pin(7, Pin.OUT)
d7 = Pin(8, Pin.OUT)

data_pins = [d4, d5, d6, d7]

## Keypad Pins
# -------------------------------
# Keypad configuration (4x4)
# -------------------------------
rows = [
    Pin(16, Pin.OUT, Pin.PULL_DOWN),
    Pin(17, Pin.OUT, Pin.PULL_DOWN),
    Pin(18, Pin.OUT, Pin.PULL_DOWN),
    Pin(19, Pin.OUT, Pin.PULL_DOWN)
    ]

cols = [
    Pin(20, Pin.IN, Pin.PULL_DOWN),
    Pin(21, Pin.IN, Pin.PULL_DOWN),
    Pin(22, Pin.IN, Pin.PULL_DOWN),
    Pin(26, Pin.IN, Pin.PULL_DOWN)
    ]

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

# -------------------------------
# Keypad scanning function
# -------------------------------
def read_key():
    for r in range(4):
        rows[r].value(1)
        for c in range(4):
            if cols[c].value() == 1:
                rows[r].value(0)
                return keys[r][c]
        rows[r].value(0)
    return None


# Enable pulse
def pulse_enable():
    en.value(1)
    time.sleep_us(1)
    en.value(0)
    time.sleep_us(1)


# Read Busy Flag (BF = D7)
def lcd_busy_wait():
    rs.value(0)   # Command register
    rw.value(1)   # Read mode

    d7.init(Pin.IN)

    while True:
        # Read high nibble (BF is D7)
        en.value(1)
        time.sleep_us(1)
        busy = d7.value()
        en.value(0)
        time.sleep_us(1)

        # Read low nibble (discarded but REQUIRED)
        en.value(1)
        time.sleep_us(1)
        en.value(0)
        time.sleep_us(1)

        if busy == 0:
            break

    d7.init(Pin.OUT)
    rw.value(0)   # Back to write mode


def send_nibble(nibble):
    for i in range(4):
        data_pins[i].value((nibble >> i) & 1)
    pulse_enable()

def send_byte(value, mode):
    lcd_busy_wait()
    rs.value(mode)
    rw.value(0)

    send_nibble(value >> 4)
    send_nibble(value & 0x0F)

def lcd_init():
    time.sleep_ms(20)

    send_nibble(0x03)
    time.sleep_ms(5)
    send_nibble(0x03)
    time.sleep_us(150)
    send_nibble(0x02)

    send_byte(0x28, 0)  # 4-bit, 2-line
    send_byte(0x0C, 0)  # Display ON
    send_byte(0x06, 0)  # Entry mode
    send_byte(0x01, 0)  # Clear display

def lcd_print(text):
    for c in text:
        send_byte(ord(c), 1)


# -------------------------------
# Main loop
# -------------------------------
lcd_init()
while True:
    key = read_key()
    
    if key:
        print("Key pressed:", key)

        
        lcd_print(key)
        time.sleep(0.3)  # debounce delay