from machine import Pin, ADC
import time

# --- Segment and digit pins ---
SEG_PINS = [Pin(i, Pin.OUT) for i in range(8)]  # A-G, DP on GPIO 0–7
DIGIT_PINS = [Pin(i, Pin.OUT) for i in [11, 10, 9, 8]]  # DIG1–DIG4
DOT_PIN = SEG_PINS[7]  # DP is pin 7

# --- ADC and button setup ---
adc = ADC(26)  # GPIO 26 = ADC0
button = Pin(16, Pin.IN, Pin.PULL_UP)

# --- 7-segment digit codes (common cathode) ---
digit_codes = [
    0b11000000,  # 0
    0b11111001,  # 1
    0b10100100,  # 2
    0b10110000,  # 3
    0b10011001,  # 4
    0b10010010,  # 5
    0b10000010,  # 6
    0b11111000,  # 7
    0b10000000,  # 8
    0b10010000   # 9
]

# --- Global display value (mV) ---
display_value = 0
last_press_time = 0  # for debounce

# --- Display a digit with optional dot ---
def display_digit(digit, digit_index, dot=False):
    segments = digit_codes[digit]
    for i in range(7):
        SEG_PINS[i].value((segments >> i) & 1)
    DOT_PIN.value(0 if dot else 1)
    DIGIT_PINS[digit_index].on()
    time.sleep(0.005)
    DIGIT_PINS[digit_index].off()

# --- Scan display to show full 4-digit number ---
def scan_display():
    value = display_value
    for i in range(3, -1, -1):  # DIG4 to DIG1
        digit = value % 10
        value //= 10
        dot = (i == 0)  # Turn on dot after first digit
        display_digit(digit, i, dot)

# --- Button interrupt: read and convert voltage ---
def button_pressed(pin):
    global display_value, last_press_time
    now = time.ticks_ms()
    if time.ticks_diff(now, last_press_time) < 200:
        return  # debounce: ignore if < 200ms
    last_press_time = now

    raw = adc.read_u16()
    voltage = (raw * 3.3) / 65535  # Convert to voltage
    mv = int(voltage * 1000)  # Convert to millivolts for display
    display_value = mv
    print("Voltage:", voltage, "V")

# Attach interrupt to button (falling edge = press)
button.irq(trigger=Pin.IRQ_FALLING, handler=button_pressed)

# --- Main loop: keep scanning display ---
while True:
    scan_display()