# imports
import machine
import math
import time
from machine import Pin, Timer
from time import sleep
#######################################
# Pin and constant definitions
#######################################
adc_output= machine.ADC(machine.Pin(26))
button = Pin(16, Pin.IN, Pin.PULL_UP)
seven_segment_start_pin = 0
display_count = 4
decimal_precision = 3
#######################################
# Global variables
#######################################

digit_list_hex = [
    0x40,  # 0
    0x79,  # 1
    0x24,  # 2
    0x30,  # 3
    0x19,  # 4
    0x12,  # 5
    0x02,  # 6
    0x78,  # 7
    0x00,  # 8
    0x10,  # 9
]
display_value = 0
segment_pins = []
display_select_pins = []
current_display_index = display_count -1
display_timer = None
timer_int= machine.Timer()
debounce=machine.Timer()
#######################################
# 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):  # We can use the pin parameter if needed
    # global display_value
    global display_value
    global adc_output
# Converting the adc's input into milivolts and assigning its value to display_value
    voltage_level = 3.3
    adc_data = adc_output.read_u16()
    volt_output= (adc_data/65535) * voltage_level
    milivolts = int(volt_output * 1000)
    display_value = milivolts
    debounce.init(mode= Timer.ONE_SHOT, period=200, callback=debounce_callback)
# Function for the button debouncing
def debounce_callback(timer):
    if button.value()==0:
        print(f'{display_value} mv')
        button.value()==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 displays
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
# Function display the given value on the display with the specified index
# dp_enable specifies if the decimal point should be on or off
# checks if the value is invalid or valid 
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)
# 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)
        sleep(0.5)
    for i in range(0, len(digit_list_hex)):
        display_digit(i, display_count -1 -(i % display_count), True)
        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
    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()
    scan_display(timer_int)
    button.irq(trigger= Pin.IRQ_FALLING, handler = read_analogue_voltage)
if __name__ == '__main__':
    setup()
    display_value_test()