MicroPython DHT11 and LCD1602 on a Pico

# The DHT11's readings on the LCD1602: the sensor on GP5, the LCD on I2C
# bus 1 (SDA GP14, SCL GP15), the temperature on the first line and the
# humidity on the second, every two seconds.
from machine import I2C, Pin
import dht
import time
from lcd1602 import LCD1602

sensor = dht.DHT11(Pin(5))
i2c = I2C(1, sda=Pin(14), scl=Pin(15), freq=400000)
lcd = LCD1602(i2c, 0x27)
time.sleep(1)

while True:
    try:
        sensor.measure()
        t, h = sensor.temperature(), sensor.humidity()
        lcd.show("Temp:  %d C" % t, "Humid: %d %%" % h)
        print("temperature", t, "humidity", h)
    except OSError:
        lcd.show("DHT11 error")
    time.sleep(2)

# lcd1602.py: a 16x2 character LCD on a PCF8574 I2C backpack.
# The backpack's P0 is RS, P2 is E, P3 is the backlight and P4 to P7 are
# the display's D4 to D7, so every byte is sent as two 4-bit halves.
import time

class LCD1602:
    def __init__(self, i2c, addr=0x27):
        self.i2c = i2c
        self.addr = addr
        self.light = 0x08
        time.sleep_ms(50)
        for half in (0x30, 0x30, 0x30, 0x20):   # wake up, then 4-bit mode
            self._half(half, 0)
            time.sleep_ms(5)
        self.command(0x28)                      # two lines, 5x8 dots
        self.command(0x0C)                      # display on, no cursor
        self.command(0x06)                      # move right after a character
        self.clear()

    def _send(self, bits):
        self.i2c.writeto(self.addr, bytes([bits | self.light]))

    def _half(self, bits, rs):
        self._send(bits | rs | 0x04)            # E high...
        self._send(bits | rs)                   # ...and low: the LCD reads it

    def _byte(self, value, rs):
        self._half(value & 0xF0, rs)
        self._half((value << 4) & 0xF0, rs)

    def command(self, value):
        self._byte(value, 0)
        if value < 4:
            time.sleep_ms(2)                    # clear and home are slow

    def clear(self):
        self.command(0x01)

    def move_to(self, col, row):
        self.command(0x80 | (col + 0x40 * row))

    def write(self, text):
        for ch in text:
            self._byte(ord(ch), 1)

    def show(self, line1, line2=""):
        self.move_to(0, 0)
        self.write("%-16s" % line1[:16])
        self.move_to(0, 1)
        self.write("%-16s" % line2[:16])