import machine
import math
import time
import utime

temp_sensor = machine.ADC(26)
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 = DISPLAY_COUNT - 1
display_timer = None
counter_timer = None

last_button_press_time = 0
debounce_delay = 150

def read_analogue_voltage():
    global display_value
    raw_val = temp_sensor.read_u16()
    voltage = ((raw_val / 65535) * 3.3)*1000
    display_value = voltage
    print("voltage : {:.0f} MV".format(voltage))
    utime.sleep(0.01)

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

def enable_display_timer(pin=None):
    global display_timer
    display_timer.init(period=30, mode=machine.Timer.PERIODIC, callback=scan_display)

def scan_display(timer_int):
    global current_display_index, display_value
    digit = int((display_value // math.pow(10, current_display_index))) % 10
    display_digit(digit, current_display_index,
                  current_display_index == DECIMAL_PRECISION and 0 != DECIMAL_PRECISION)
    current_display_index = (current_display_index - 1)
    if current_display_index < 0:
        current_display_index = DISPLAY_COUNT - 1

def display_digit(digit_value, digit_index, dp_enable=False):
    if digit_value < 0 or digit_value > len(digit_list_hex):
        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(1 if dp_enable == False else 0)
    if digit_index == -1:
        for pin in display_select_pins:
            pin.value(1)
    elif 0 <= digit_index < DISPLAY_COUNT:
        display_select_pins[digit_index].value(1)

def display_value_test():
    global display_value
    disable_display_timer()
    current_display_index = 0
    for i in range(0, len(digit_list_hex)):
        display_digit(i, -1, i % 2 != 0)
        time.sleep(0.5)
    for i in range(0, len(digit_list_hex)):
        display_digit(i, DISPLAY_COUNT - 1 - (i % DISPLAY_COUNT), True)
        time.sleep(0.5)
    display_digit(16, -1, False)
    enable_display_timer()

def setup():
    global segment_pins, display_select_pins
    global display_timer, counter_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)
    display_timer = machine.Timer()
    enable_display_timer()
    button = machine.Pin(19, machine.Pin.IN, machine.Pin.PULL_UP)
    button.irq(trigger=machine.Pin.IRQ_FALLING, handler=button_handler)

def button_handler(pin):
    global last_button_press_time
    current_time = time.ticks_ms()
    if time.ticks_diff(current_time, last_button_press_time) > debounce_delay:
        read_analogue_voltage()
        enable_display_timer()
        last_button_press_time = current_time

if __name__ == '__main__':
    setup()
    disable_display_timer()