import machine
import time

seg_start = 0
adc_pin = 26
btn_pin = 16
num_digits = 4
samples = 1
decimals = 3
adc_max = float((2 ** 16) - 1)
btn_delay = 50

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

curr_val = 0
seg_pins = []
dig_pins = []
adc = None
btn = None
digit = num_digits - 1
t = None
last_val = -1
last_btn = 0

def read_val(adc):
    global curr_val, last_val
    val = sum(adc.read_u16() for _ in range(samples)) // samples
    volt = round((val / adc_max) * 3.3, decimals)
    if volt != last_val:
        last_val = volt
        to_display = int(volt * (10 ** decimals))
        if to_display > (10 ** num_digits - 1):
            to_display = 10 ** num_digits - 1
        if curr_val != to_display:
            curr_val = to_display
            clear_display()
        return volt

def stop_disp():
    global t
    t.deinit()

def start_disp():
    global t
    t.init(period=4, mode=machine.Timer.PERIODIC, callback=show_next)

def show_next(timer):
    global digit, curr_val
    val = int(abs(curr_val) // (10 ** digit)) % 10
    draw(val, digit, digit == decimals and decimals != 0)
    digit = (digit - 1) % num_digits

def draw(val, pos, dot=False):
    if val < 0 or val >= len(hex_map):
        return
    for p in dig_pins:
        p.value(0)
    bits = hex_map[val]
    for i in range(7):
        seg_pins[i].value((bits >> i) & 1)
    seg_pins[7].value(not dot)
    if pos == -1:
        for p in dig_pins:
            p.value(1)
    elif 0 <= pos < num_digits:
        dig_pins[pos].value(1)

def clear_display():
    global digit
    stop_disp()
    digit = num_digits - 1
    draw(16, -1)
    time.sleep(0.1)
    start_disp()

def setup():
    global seg_pins, dig_pins, adc, btn, t
    dig_pins = [machine.Pin(i, machine.Pin.OUT) for i in range(seg_start + 8, seg_start + 8 + num_digits)]
    for p in dig_pins:
        p.value(0)
    seg_pins = [machine.Pin(i, machine.Pin.OUT) for i in range(seg_start, seg_start + 8)]
    for p in seg_pins:
        p.value(1)
    adc = machine.ADC(adc_pin)
    btn = machine.Pin(btn_pin, machine.Pin.IN, machine.Pin.PULL_UP)
    t = machine.Timer()
    start_disp()

if __name__ == '__main__':
    setup()
    while True:
        if btn.value() == 0:
            now = time.ticks_ms()
            if now - last_btn > btn_delay:
                last_btn = now
                v = read_val(adc)
                if v is not None:
                    print(f"Voltage: {v} V")
        time.sleep(0.1)