# Importing Libraries.

import machine
import math
import time
from machine import ADC

#-------------------------------------------------
# Pin And Constant Definitions.

SEVEN_SEGMENT_START_PIN = 0
DISPLAY_COUNT = 4
DECIMAL_PRECISION = 3
last_button_time = 0  # To Keep Track Of When The Button Was Last Pressed.
DEBOUNCE_DELAY = 200  # 200 Ms Debounce Time.
button_pin = None

digit_list_hex = [
    0x40,  # 0
    0x79,  # 1
    0x24,  # 2
    0x30,  # 3
    0x19,  # 4
    0x12,  # 5
    0x02,  # 6
    0x78,  # 7
    0x00,  # 8
    0x10,  # 9
    0x08,  # A
    0x03,  # B
    0x46,  # C
    0x21,  # D
    0x06,  # E
    0x0E,  # F
    0x7F   # Empty
]

#-------------------------------------------------
# Global Variables.

should_display = False
display_value = 0
segment_pins = []
display_select_pins = []
current_display_index = DISPLAY_COUNT -1  # To Keep Track Of Which Digit Is Currently Being Displayed.
display_timer = None
counter_timer = None

#-------------------------------------------------
# Function Definitions.
#-------------------------------------------------
# Function To Read The ADC Pin And To Convert The Digital Value To A Voltage Level In The 0-3.3V Range, This Function Updates The Value Of The display_value Global Variable.

def read_analogue_voltage(pin=26):
    global display_value, current_display_index
    adc = ADC(machine.Pin(pin))
    adc_value = adc.read_u16()
    voltage = (adc_value / 65535.0) * 3.3
    print("Voltage:", round(voltage, 3), "V")
    display_value = int(round(voltage * 1000))  # For Example: 1.031 V becomes 1031
    current_display_index = DISPLAY_COUNT - 1

#-------------------------------------------------
# Function To Disable Timer That Triggers Scanning 7 Segment Displays.

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

#-------------------------------------------------
# Function To Enable Timer That Triggers Scanning 7 Segment Displays.

def enable_display_timer():
    global display_timer
    display_timer.init(period=30, mode=machine.Timer.PERIODIC, callback=scan_display)

#-------------------------------------------------
# Function To Handle Scanning 7 Segment Displays, Display The Value Stored In The display_value Global Variable, On Available 7-Segment Display.

def scan_display(timer_int):
    global current_display_index, display_value

    # Turn Off All Digits
    for pin in display_select_pins:
        pin.value(0)

    # Extract Digit Starting From Right (least significant)
    digit = (display_value // (10 ** current_display_index)) % 10
    show_dp = (current_display_index == 3)
    display_digit(digit, current_display_index, show_dp)
    current_display_index = (current_display_index + 1) % DISPLAY_COUNT

#-------------------------------------------------
# Function Display The Given Value On The Display With The Specified Index.

def display_digit(digit_value, digit_index, dp_enable=False):
    if digit_value < 0 or digit_value > 15:
        digit_value = 16
    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)
    for pin in display_select_pins:
        pin.value(0)
    if 0 <= digit_index < DISPLAY_COUNT:
        display_select_pins[digit_index].value(1)
   
#-------------------------------------------------
# Function To Test Avaiable 7-Segment Displays.

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()     

#-------------------------------------------------
# Function To Setup GPIO/ADC Pins, Timers And Interrupts.

def setup():
    global segment_pins, display_select_pins
    global display_timer, button_pin

    button_pin = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)  # Active LOW.
    button_pin.irq(trigger=machine.Pin.IRQ_FALLING, handler=handle_button_press)  # Set Up Push Button Interrupt For Press.

    # Set Up Display Select Pins.
    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)

    # Set Up Seven Segment Pins.
    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()

#-------------------------------------------------
# Function For Button Deboucing.

def handle_button_press(pin):
    global last_button_time

    now = time.ticks_ms()
    if time.ticks_diff(now, last_button_time) < DEBOUNCE_DELAY:
        return
    time.sleep_ms(20)
    if pin.value() == 0:
        last_button_time = now
        read_analogue_voltage()

#-------------------------------------------------
if __name__ == '__main__':
    setup()