# Exercise 12(e)

from machine import Pin, ADC, Timer
from neopixel import NeoPixel
from time import sleep

# set colours all to zero initially
red=0
green=0
blue=0

# Initialize 16-pixel ring on GPIO pin 12
ring = NeoPixel(Pin(12), 16)

pot1 = ADC(Pin(36)) # pin 36 will be used as an ADC input line
pot2 = ADC(Pin(39)) # pin 39 will be used as an ADC input line
pot3 = ADC(Pin(34)) # pin 34 will be used as an ADC input line

switch = Pin(19,Pin.IN,Pin.PULL_UP)  # configure the target GPIO line as an input

def my_timer_ISR (timer):  # internal interrupt service routine (ISR)
    global red,green,blue
    red = int(pot1.read()/16)
    green = int(pot2.read()/16)
    blue = int(pot3.read()/16)

my_timer = Timer(0)
my_timer.init(mode = Timer.PERIODIC, period = 100, callback = my_timer_ISR )


def My_ISR(pin): # external interrupt Service Routine (ISR)
    global direction # global variable the ISR code can update
    
    if direction == True: 
        direction = False
    else:
        direction =True

# Attach the interrupt to the GPIO line using the irq() method
switch.irq(handler= My_ISR, trigger = Pin.IRQ_FALLING)


# starting condition:-  clockwise direction  starting at element number 0
direction = True
position = 0


while True:

    if direction==True:      # clockwise direction
        position=position+1
        if position==16:     # need to reset position to 0 to start next rotation
            position=0
    else:                   # anti-clockwise direction
        position=position-1
        if position==-1:    # need to set position to 15 to start next rotation
            position=15
        
    ring[position] = (red, green, blue)     
    ring.write()
    sleep(0.25)