RaspberryPi with DHT22 Sensor for Humidity and Temperature Data with InfluxDB
I have been playing with RaspberryPI for a while. There are several project I tried to do with RaspberryPI. These boards play a significant role in my home lab for different experiments like Docker Private Repository, Media Server, Ad Blocker with pi-hole, Secure Proxy for anonymity, secure network access with VPN, Home Security Camera/Surveillance, Data Collector or scraper etc. But This time, I did buy a “DHT-22” sensor for monitoring room temperature and humidity. Humidity is my main concern and wanted to see how it fluctuates.
So, my main plan was to get a DHT-22 to connect properly
with my spare RapberryPI 3B+. I did order the sensor and 3 male-to-male jumper for connectivity. Though I should have had a BreadBoard too. However, raspberryPI had already Ubuntu Server 20 installed.
GPIO Pins of Raspberry PI
For DHT-22, I needed to connect the female-to-female into the pins
14: Ground 17: 3v3 Power 18: GPIO 24
This GPIO-24 was important to note down as it was needed in Python Code to access the sensor through this pin.
Yes, I have used python to access the sensor. For testing, I have used this code:
#!/usr/bin/python3
import Adafruit_DHT
import datetime
def th_reader():
# for DHT11
# sensor = 11
# for DHT22
sensor = 22
gpio = 24
h_t = Adafruit_DHT.read_retry(sensor, gpio)
humidity = h_t[0]
temperature = h_t[1]
if humidity is not None and temperature is not None:
temp = '{0:0.1f}°C'.format(temperature)
humid = '{0:0.1f}%'.format(humidity)
return {
"temperature": temp,
"humidity": humid
}
else:
temp = None
humid = None
return {
"temperature": temp,
"humidity": humid
}
if __name__ == '__main__':
print(th_reader())
This was enough for me. I wanted to run the script every 5 minutes through cron and store the data to already running influxDB instance in another RaspberryPI at which I can create dashboards and others. You can check how I am using InfluxDB through here: https://fahadahammed.com/explore-influxdb-part-1/
So, I did create a bucket in the influxDB and modified the code to this-
#!/usr/bin/python3
import Adafruit_DHT
import datetime
import threading
from influxdb_client import InfluxDBClient, Point, WritePrecision
from influxdb_client.client.write_api import SYNCHRONOUS
def th_reader():
# for DHT11
# sensor = 11
# for DHT22
sensor = 22
gpio = 24
h_t = Adafruit_DHT.read_retry(sensor, gpio)
humidity = h_t[0]
temperature = h_t[1]
if humidity is not None and temperature is not None:
temp = '{0:0.1f}°C'.format(temperature)
humid = '{0:0.1f}%'.format(humidity)
return {
"temperature": temperature,
"humidity": humidity
}
else:
temp = None
humid = None
return {
"temperature": temp,
"humidity": humid
}
def write_to_influxdb(data_to_write):
# You can generate an API token from the "API Tokens Tab" in the UI
token = "<INFLUX_TOKEN>"
org = "myorg"
bucket = "dht"
influx_url = "<INFLUX_URL>"
with InfluxDBClient(url=influx_url, token=token, org=org) as client:
write_api = client.write_api(write_options=SYNCHRONOUS)
pt = Point("temperature").tag("host", "pi").field("temperature", int(data_to_write.get("temperature"))).time(datetime.datetime.utcnow(), WritePrecision.NS)
write_api.write(bucket, org, pt)
client.close()
with InfluxDBClient(url=influx_url, token=token, org=org) as client:
write_api = client.write_api(write_options=SYNCHRONOUS)
ph = Point("humidity").tag("host", "pi").field("humidity", data_to_write.get("humidity")).time(datetime.datetime.utcnow(), WritePrecision.NS)
write_api.write(bucket, org, ph)
client.close()
return True
if __name__ == '__main__':
th_data = th_reader()
print(th_data)
# write_to_influxdb(data_to_write=th_data)
t1 = threading.Thread(target=write_to_influxdb, kwargs={"data_to_write": th_data})
t1.start()
If you want to use the code block, please do replace the <INFLUX_URL> and <INFLUX_TOKEN> with valid ones.
Now the output is the same json but without the ‘%’ and ‘°C’. Because I needed to get a numerical value and set the required prefixes in graph.
I have used InfluxDB Data Point to write data.
Temperature & Humidity via DHT22 Sensor Dashboard
Exported JSON of this minimal dashboard is-
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I have other plans to use the DHT-22 like controlling exhaust fan or similar. Maybe later. For now, I will just collect data and observe the fluctuation of my rooms temperature and humidity.
It was fun working with InfluxDB and DHT-22 with RaspberryPI.
Thanks for reading. Please give me feedback If you have idea for me or point me some improvements.
