# 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 = 3
ADC_RANGE = 65535

# 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 = None
current_display_index = 3  # to keep track of which digit is currently being displayed
display_timer = None
prev_analogue_voltage = -1

#######################################
# Function definitions
#######################################
pbpushed = False
st = 0
def pbutton(pin):
    global pbpushed
    global st
    ct = time.ticks_ms()
    if ct - st > 200:
        pbpushed = True
        st = ct

pb = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)
pb.irq(trigger=machine.Pin.IRQ_FALLING, handler=pbutton)

def read_analogue_voltage(pin):
    global display_value, prev_disp_val, display_timer
    global prev_analogue_voltage, DECIMAL_PRECISION
    read_value = pin.read_u16()
    analogue_value = round((read_value * 3.3)/ 65535, 3)
    new_display_value = analogue_value * 1000

    max_value = 9999
    if new_display_value > max_value:
        new_display_value = max_value
        print("too large")
    if new_display_value != display_value:
        print(f"voltage is {analogue_value} mV")
        display_value = new_display_value
        disable_display_timer()
        current_display_index = 3
        display_digit(16, -1)
        time.sleep(0.1)
        enable_display_timer()

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

def enable_display_timer():
    global display_timer
    display_timer.init(period = 4, mode = machine.Timer.PERIODIC, callback = scan_display)

def scan_display(timer_int):
    global current_display_index, display_value

    display = int((display_value // 10**current_display_index %10))
    display_digit(display, current_display_index, current_display_index == 3)

    current_display_index = current_display_index - 1
    if current_display_index < 0:
        current_display_index = 3

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)

    for i in range(7):
        segment_pins[i].value((digit_list_hex[digit_value] >> 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 setup():
    global SEVEN_SEGMENT_START_PIN, DISPLAY_COUNT, analogue_voltage_pin, display_timer, display_select_pins,segment_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)

    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)

    analogue_voltage_pin = machine.ADC(26)
    display_timer = machine.Timer()
    enable_display_timer()



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

    while True:
        if pbpushed == True: 
            read_analogue_voltage(analogue_voltage_pin)
            time.sleep(0.5)
            pbpushed = False