Python script to measure temperature and humidity using the Seeed Grove DHT20 sensor

dht20.py

#!/usr/bin/python3
import smbus
import time
import argparse

try: 
    bus = smbus.SMBus(1)
except PermissionError:
    print("Could not open I2C bus: Permission denied.")
    print("Try re-running the script as root.")
    exit(1)

my_data = [0x33, 0x00]

def read_dht20():
    bus.write_i2c_block_data(0x38, 0xAC, my_data)
    time.sleep(0.08)
    data = bus.read_i2c_block_data(0x38, 1, 7)

    temp = 0
    temp = (temp | data[3]) << 8
    temp = (temp | data[4]) << 8
    temp = temp | data[5]
    temp = temp & 0xfffff
    temp = (temp * 200 * 10 / 1024 / 1024 - 500)/10

    humidity = 0
    humidity = (humidity | data[1]) << 8
    humidity = (humidity | data[2]) << 8
    humidity = humidity | data[3]
    humidity = humidity >> 4
    humidity = (humidity * 100 * 10 / 1024 / 1024)/10
    return (temp, humidity)

parser = argparse.ArgumentParser()
parser.add_argument("metric")
args = parser.parse_args()

data = read_dht20()
if args.metric == "temp":
    print(data[0])
    exit(0)
elif args.metric == "humid":
    print(data[1])
    exit(0)
else:
    print("Unsupported metric.")
    exit(1)