import machine
import math
import time

SEVEN_SEGMENT_START_PIN = 0
DISPLAY_COUNT = 4
DECIMAL_PRECISION = 3

digit_list_hex = [
    0x40, 0x79, 0x24, 0x30, 0x19, 0x12,
    0x02, 0x78, 0x00, 0x10, 0x08, 0x03,
    0x46, 0x21, 0x06, 0x0E, 0x7F
]

display_value = 0
segment_pins = []
display_select_pins = []
current_display_index = 0
display_timer = None
last_button_time = 0
adc = machine.ADC(26)

button_pin = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)

def disable_display_timer():
    global display_timer
    display_timer.deinit()

def enable_display_timer():
    global display_timer
    display_timer.init(period=10, mode=machine.Timer.PERIODIC, callback=scan_display)

def scan_display(timer):
    global current_display_index, display_value
    formatted = "{:04d}".format(round(display_value * 1000))
    formatted = ''.join(reversed(formatted))
    digit_char = formatted[current_display_index]
    digit = int(digit_char)
    show_dot = (current_display_index == DECIMAL_PRECISION)
    display_digit(digit, current_display_index, show_dot)
    current_display_index = (current_display_index + 1) % DISPLAY_COUNT

def display_digit(digit_value, digit_index, dp_enable=False):
    if digit_value < 0 or digit_value > 9:
        return

    for pin in display_select_pins:
        pin.value(0)

    mask = digit_list_hex[digit_value]
    for i in range(7):
        segment_pins[i].value((mask >> i) & 1)

    segment_pins[7].value(0 if dp_enable else 1)

    if 0 <= digit_index < DISPLAY_COUNT:
        display_select_pins[digit_index].value(1)

def update_reading():
    global display_value
    readings = [adc.read_u16() for _ in range(16)]
    avg = sum(readings) / len(readings)
    voltage = (avg * 3.3) / 65535
    display_value = voltage
    print(f"Voltage: {voltage:.3f} V")

def button_handler(pin):
    global last_button_time
    now = time.ticks_ms()
    if time.ticks_diff(now, last_button_time) > 200:
        last_button_time = now
        update_reading()

def setup():
    global segment_pins, display_select_pins, display_timer

    for i in range(SEVEN_SEGMENT_START_PIN + 8, SEVEN_SEGMENT_START_PIN + 8 + DISPLAY_COUNT):
        pin = machine.Pin(i, machine.Pin.OUT)
        pin.value(0)
        display_select_pins.append(pin)

    for i in range(SEVEN_SEGMENT_START_PIN, SEVEN_SEGMENT_START_PIN + 8):
        pin = machine.Pin(i, machine.Pin.OUT)
        pin.value(1)
        segment_pins.append(pin)

    update_reading()
    button_pin.irq(trigger=machine.Pin.IRQ_FALLING, handler=button_handler)
    display_timer = machine.Timer()
    enable_display_timer()

setup()
while True:
    time.sleep(1)