from machine import I2C, Pin, ADC
from i2c_lcd import I2cLcd
from utime import sleep,sleep_ms

DEFAULT_I2C_ADDR = 0x27                         # LCD 1602 I2C address
i2c = I2C(0,sda=Pin(0),scl=Pin(1),freq=400000) 
lcd = I2cLcd(i2c, DEFAULT_I2C_ADDR,2, 16)      # Initialize(device address, backlight settings)
Potentiometer=ADC(0)

maxSleep=2
noofSpace=3                                     #no. of spaces between text
txt='Pico LCD'
space=" "*noofSpace								
txt=txt+space									
tmp=txt
cPtr=0											#character pointer
sPtr=0											#screen pointer
fcPtr=0											#character pointer at the first digit of the LCD
dire=1											#direction indicator 1=scroll to left, -1=scroll to right, 0=still
adcR=0											#analog to digital converter reading min=0 to max=65535
sec=1											#maximum seconds 

while True:
    adcR=Potentiometer.read_u16()
    if adcR<20000:								#define direction and seconds according to the reading from the potentiometer (0 to 20000)
        dire=1									
        sec=maxSleep*adcR/20000					#relation between sleep and potentiometer input are calculated by slope equation
    elif adcR>40000:							#define direction and seconds according to the reading from the potentiometer (40000 to 65535)
        dire=-1
        sec=-(maxSleep*adcR/(65535-40000))+((1+(40000/(65535-40000)))*maxSleep)+0.1	#slope equation
    else:										#stop region (20000 to 40000)
        dire=0
    if abs(cPtr)>=len(txt):						#character looping after last character
        cPtr=0
    if sPtr==0:									#store the pointing number of the character at the first position of the LCD
        fcPtr=cPtr
    tmp=txt[cPtr]
    lcd.move_to(sPtr,0)
    lcd.putstr(tmp)								#put character on the LCD one by one 
    sPtr=sPtr+1
    cPtr=cPtr+1
    if sPtr>=16:								#the pointer at the LCD display returns to the first position after the last position
        sPtr=0
        cPtr=fcPtr+dire
        sleep(sec)
        lcd.clear()