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Created October 27, 2022 17:18
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Sensirion CO2 Gadget BLE <-> Python
Raw
README.md

Sensirion CO2 Gadget BLE <-> Python

  • BLE Library Docs: Bleak
    • Might have to pip3 install bleak first
  • Protocol Docs from Sensirion: Link
    • I'm listening for the BLE advertisement here (see p4 for data structure)
    • Calculation of measurements from ticks see p7, "3.9 Sample 8"
  • You can get the device address from the scan.py script (doesn't always show the name for some reason) or a tool like BlueSee
  • Code to get the data is in log-data.py
Raw
log-data.py
#!/opt/homebrew/bin/python3
import sys
import asyncio
import platform
from bleak import BleakScanner
ADDRESS = "993192E4-7572-D322-B8C8-589626F55B6D"
CHAR_UUID = "00007001-B38D-4985-720E-0F993A68EE41"
def log_data(data: bytearray):
byte_order = "little"
raw = list(data.values())[0]
data_str = ' '.join('{:02x}'.format(x) for x in raw)
t_ticks = int.from_bytes(raw[4:6], byte_order, signed=False)
t = -45 + ((175 * t_ticks) / (2**16-1))
rh_ticks = int.from_bytes(raw[6:8], byte_order, signed=False)
rh = (100 * rh_ticks) / (2**16-1)
co2 = int.from_bytes(raw[8:10], byte_order, signed=False)
print(f"{data_str}\t{t:.3f}C\t\t{rh:.3f}%\t\t{co2}ppm")
def detection_callback(device, advertisement_data):
if device.address == ADDRESS:
log_data(advertisement_data.manufacturer_data)
async def main():
stop_event = asyncio.Event()
print("Listening for sensor data from address:")
print(ADDRESS)
print("")
print("Raw data:\t\t\tTemp.:\t\tRH:\t\tCO2:")
async with BleakScanner(detection_callback) as scanner:
await stop_event.wait()
if __name__ == "__main__":
asyncio.run(main())
Raw
scan.py
#!/opt/homebrew/bin/python3
import asyncio
from bleak import BleakScanner
async def main():
devices = await BleakScanner.discover()
for d in devices:
print(d)
asyncio.run(main())
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