# imports
import machine
import math
import time

#######################################
# Pin and constant definitions
#######################################
SEVEN_SEGMENT_START_PIN = 0
ANALOGUE_INPUT_PIN = 26
DISPLAY_COUNT = 4
MEASUREMENT_COUNT = 16
DECIMAL_PRECISION = 4
ADC_RANGE = float((math.pow(2, 16) - 1))
button = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)





# HEX values for 7 segment display values
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
#######################################
display_value = 0
segment_pins = []
display_select_pins = []
analogue_voltage_pin = machine.ADC(ANALOGUE_INPUT_PIN)
current_display_index = DISPLAY_COUNT -1  # to keep track of which digit is currently being displayed
display_timer = None
prev_analogue_voltage = -1
button_pressed = False
last_button_time_stamp = 0
DECIMAL_PRECISION = 4
#######################################
# 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, prev_disp_val, display_timer
    global prev_analogue_voltage, DECIMAL_PRECISION

    # Take MEASUREMENT_COUNT measurements and average them
    total_value = 0
    for _ in range(MEASUREMENT_COUNT):
        total_value += pin.read_u16()
    average_value = total_value // MEASUREMENT_COUNT

    # Convert the average digital value to an analogue voltage value
    analogue_voltage = int(round((average_value / ADC_RANGE) * 3.3 * 1000))
    if analogue_voltage != prev_analogue_voltage:
        prev_analogue_voltage = analogue_voltage

           # Display on serial monitor in mV
        print(f'Voltage: {analogue_voltage} mV')

        # Dynamically adjust DECIMAL_PRECISION based on voltage range
        if analogue_voltage < 1000:
            DECIMAL_PRECISION = 4
        else:
            DECIMAL_PRECISION = 3


        new_display_value = int(analogue_voltage / 1000 * math.pow(10, DECIMAL_PRECISION))

            
        max_val = math.pow(10, DISPLAY_COUNT) - 1
        if new_display_value > max_val:
            print(f'warn: {new_display_value} exceeds {max_val}, clipping')

        display_value = new_display_value
        disable_display_timer()
        scan_display(None)
        enable_display_timer()
        display_digit(16, -1)
        time.sleep(0.1)
      
      


# 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=4, 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):
    global current_display_index, display_value

 # Extract the digit corresponding to the current display index
    # Only display positive values
    digit = int((abs(display_value) // math.pow(10, current_display_index))) % 10

    # Display the digit,
    # enable the decimal point if the current digit index equals to the set decimal precision
    display_digit(digit, current_display_index, current_display_index != DECIMAL_PRECISION)

    # Move to the next display
    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 pooint should be on or off
def display_digit(digit_value, digit_index, dp_enable=False):
    # Ensure the value is valid
    if digit_value < 0 or digit_value > len(digit_list_hex):
        return

     # Deselect all display select pins
    for pin in display_select_pins:
        pin.value(0)

    # Set the segments according to the digit value
    mask = digit_list_hex[digit_value]
    for i in range(7):  # 7 segments from A to G
        segment_pins[i].value((mask >> i) & 1)

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

    # If digit_index is -1, activate all display select pins
    if digit_index == -1:
        for pin in display_select_pins:
            pin.value(1)
    # Otherwise, ensure the index is valid and activate the relevant display select pin
    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)
        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 count_display_value(timer_int):
    global display_value
    display_value += 1
    if display_value > 9999:
        display_value = 0
    #print(display_value)


# Interrupt handler for button press
def int_handler(pin):
    global button_pressed, last_button_time_stamp

    current_button_time = time.ticks_ms()
    button_press_delta = current_button_time - last_button_time_stamp
    if button_press_delta > 200:
        last_button_time_stamp = current_button_time
        button_pressed = True




# Function to setup GPIO/ADC pins, timers and interrupts
def setup():
    global segment_pins, display_select_pins
    global display_timer, counter_timer

    # 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)

    # Start the timer interrupt for scanning
    display_timer = machine.Timer()
    enable_display_timer()




    # Setup button interrupt
    button.irq(trigger=machine.Pin.IRQ_FALLING, handler=int_handler)

   
    

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

  while True:
      if button_pressed is True:

         button_pressed = False
         read_analogue_voltage(analogue_voltage_pin)
  time.sleep(0.5)