Infinite loop in Python

If I have not understood correctly, your problem would be summarized as follows:

The code you've presented looks like a mix built by short & paste from different places. There is a function called write_to_lcd() , without documentation of what it does, which apparently dumps as many lines as elements have the framebuffer list that it receives as a parameter, "truncating" the displayed to only the first numcol letters.

Another function called loop_string() , also undocumented, apparently deals with repeatedly calling write_to_lcd() , passing a slightly modified framebuffer in each iteration, so that the effect is that the text shown on the lcd "scroll "horizontal.

Assuming that we want to use these functions already given, the first thing would be to define them at the beginning of the program, and not within a if as they are now. The second thing would be to give your program this structure:

repetir infinitas veces:
    tomar qué hora es
    tomar la cotización del bitcoin
    mostrar esa información en el display
    dormir un tiempo (por ejemplo 1s)

The simple part is to repeat infinity, because it is simply while True . The rest is not so complicated either, since you already have it written in your program. Everything consists in organizing it better. We will write a function to get what time it is. Another to get the bitcoin change, and two others (which were already in your code) to show data. I do not understand the reason why you install two displays with exactly the same parameters, so I have reduced it to one.

Read the code and its comments to understand how it works to see if it's what you asked for.

from RPLCD import CharLCD
import json
import requests
import time

def get_time():
    """Esta función retorna la hora actual en el formato a mostrar en el display"""
    return time.strftime("Hora: "+"%H:%M")

def get_bpi():
    """Esta función retorna el 'long_string' con las cotizaciones del bitcoin
    tal como queremos que aparezca en el display"""
    url = 'https://api.coindesk.com/v1/bpi/currentprice.json' #url
    response = requests.get(url)
    if response.status_code == 200: #si status = 200 se ejecuta esto
        data = json.loads(response.text)
        val_dol = data['bpi']['USD']['rate']+"  " #busca el valor en la ubicacion en USD
        val_eur = data['bpi']['EUR']['rate']+"  " #busca el valor en la ubicacion en EUR
        val_gbp = data['bpi']['GBP']['rate']+"" #busca el valor en la ubicacion en GBP
        return "BTC/USD: {} BTC/EUR: {} BTC/GBP: {}".format(val_dol, val_eur, val_gbp)
    else:
        return "Cotizaciones no disponibles"

def write_to_lcd(lcd, framebuffer, num_cols):
    """Esta funcion vuelca un framebuffer a un display, truncándolo a los num_clos
    primeros caracteres"""
    lcd.home()
    for row in framebuffer:
        lcd.write_string(row.ljust(num_cols)[:num_cols])
        lcd.write_string('\r\n')

def loop_string(string, lcd, framebuffer, row, num_cols, delay=0.8):
    """Esta función prepara una fila del framebuffer recibido de modo que
    muestre la cadena recibida como primer parámetro desplazándose hacia
    la izquierda hasta haberla mostrado completa y luego retorna.
    El parámetro 'delay' controla la velocidad del desplazamiento"""
    padding = ' ' * num_cols
    s = padding + string + padding
    for i in range(len(s) - num_cols + 1):
        framebuffer[row] = s[i:i+num_cols]
        write_to_lcd(lcd, framebuffer, num_cols)
        time.sleep(delay)


# Programa principal

# Inicizar el LCD
lcd = CharLCD(cols=16, rows=2, pin_rs=37, pin_e=35, pins_data=[33, 31, 29, 23]) #definimos los pines

# Mostrar mensaje inicial 4 segundos
lcd.write_string(u'Bitcoin Tracker\n\rBy ElTallerDeTD')
time.sleep(4)
lcd.clear()

framebuffer = ['', ''] # Información a mostrar en cada fila del LCD

while True:
    framebuffer[0] = get_time()  # Actualizar la hora en cada iteración del bucle
    long_string = get_bpi()

    # Mostrar hora y texto deslizante con la cotización
    loop_string(long_string, lcd, framebuffer, 1, 16, 0.3)
    # Esperar 1 seg y repetir bucle
    time.sleep(1)

Look at a detail. The function loop_string() will take a while to return since until it has not finished moving the chain and has shown it whole, it does not return. Depending on the length of that string and the delay parameter, it will take more or less to finish. Once finished, time.sleep(1) sleeps a second, which adds to the time spent per loop_string() . If for example loop_string() takes 4 seconds to finish, then the infinto loop would repeat every 4 + 1 = 5 seconds. The time (and the bitcoin quote) are therefore not updated "in real time", but only every time.