ht2000 ht-2000 co2 monitor pooler

ht2000 pool to json.py

import os
import json
import time
from struct import unpack_from
from datetime import datetime

import usb.core
import usb.backend.libusb1


script_dir = os.path.dirname(os.path.realpath(__file__))
libusb_path = os.path.join(script_dir, 'libusb-1.0.dll')
backend = usb.backend.libusb1.get_backend(find_library=lambda x: libusb_path)
dev = usb.core.find(idVendor=0x10c4, idProduct=0x82cd, backend=backend)

bmRequestType = usb.util.build_request_type(
    usb.util.CTRL_IN,
    usb.util.CTRL_TYPE_CLASS,
    usb.util.CTRL_RECIPIENT_INTERFACE
)

while True:
    buffer = dev.ctrl_transfer(
        bmRequestType=bmRequestType,
        bRequest=1,
        wValue=0x0105,
        wIndex=0,
        data_or_wLength=61
    )

    # https://github.com/eschava/HT2000-java/blob/master/src/com/eschava/ht2000/usb/HT2000State.java
    timestamp = int(time.time())
    (T, RH, CO2) = unpack_from('>Bh13xh', buffer, 8)
    T += 112
    T /= 10.0
    RH /= 10.0

    # Write current values to last.json
    last_json_path = os.path.join(script_dir, 'data', 'last.json')
    if not os.path.exists(os.path.dirname(last_json_path)):
        os.makedirs(os.path.dirname(last_json_path))
    with open(last_json_path, 'w') as f:
        f.write(json.dumps({
            'timestamp': timestamp,
            'CO2': CO2,
            'T': T,
            'RH': RH,
        }))

    # Write current values to csv storage
    now = datetime.now()
    storage_file = os.path.join(
        script_dir,
        'data',
        now.strftime('%Y'),
        now.strftime('%Y%m%d.csv')
    )
    if not os.path.exists(os.path.dirname(storage_file)):
        os.makedirs(os.path.dirname(storage_file))
    with open(storage_file, 'a') as f:
        f.write('%d,%d,%.1f,%.1f\n' % (timestamp, CO2, T, RH))
    
    time.sleep(3)