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.
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())
The output it gives-
{'temperature': '26.1°C', 'humidity': '85.8%'}
But the requirements to run the code is-
sudo apt-get update
sudo apt-get install python3-pip
sudo python3 -m pip install --upgrade pip setuptools wheel
sudo pip3 install Adafruit_DHTYou can check other methods to install from here: https://github.com/adafruit/Adafruit_Python_DHT
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.
Exported JSON of this minimal dashboard is-
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| { | |
| "meta": { | |
| "version": "1", | |
| "type": "dashboard", | |
| "name": "Temperature & Humidity via DHT22 Sensor-Template", | |
| "description": "template created from dashboard: Temperature & Humidity via DHT22 Sensor" | |
| }, | |
| "content": { | |
| "data": { | |
| "type": "dashboard", | |
| "attributes": { | |
| "name": "Temperature & Humidity via DHT22 Sensor", | |
| "description": "" | |
| }, | |
| "relationships": { | |
| "label": { | |
| "data": [] | |
| }, | |
| "cell": { | |
| "data": [ | |
| { | |
| "type": "cell", | |
| "id": "08fc4b18c8fe1000" | |
| }, | |
| { | |
| "type": "cell", | |
| "id": "08fc4b9c79fe1000" | |
| }, | |
| { | |
| "type": "cell", | |
| "id": "08fc4dc3b5fe1000" | |
| }, | |
| { | |
| "type": "cell", | |
| "id": "08fc4e064fbe1000" | |
| } | |
| ] | |
| }, | |
| "variable": { | |
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| "included": [ | |
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| "id": "08fc4b18c8fe1000", | |
| "type": "cell", | |
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| "y": 0, | |
| "w": 6, | |
| "h": 3 | |
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| "relationships": { | |
| "view": { | |
| "data": { | |
| "type": "view", | |
| "id": "08fc4b18c8fe1000" | |
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| { | |
| "id": "08fc4b9c79fe1000", | |
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| { | |
| "id": "08fc4dc3b5fe1000", | |
| "type": "cell", | |
| "attributes": { | |
| "x": 6, | |
| "y": 3, | |
| "w": 6, | |
| "h": 3 | |
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| "relationships": { | |
| "view": { | |
| "data": { | |
| "type": "view", | |
| "id": "08fc4dc3b5fe1000" | |
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| { | |
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| "id": "08fc4e064fbe1000" | |
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| }, | |
| { | |
| "type": "view", | |
| "id": "08fc4b18c8fe1000", | |
| "attributes": { | |
| "name": "Humidity", | |
| "properties": { | |
| "shape": "chronograf-v2", | |
| "type": "gauge", | |
| "queries": [ | |
| { | |
| "text": "from(bucket: \"dht\")\n |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n |> filter(fn: (r) => r[\"_measurement\"] == \"humidity\")\n |> filter(fn: (r) => r[\"_field\"] == \"humidity\")\n |> filter(fn: (r) => r[\"host\"] == \"pi\")\n |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n |> yield(name: \"mean\")", | |
| "editMode": "advanced", | |
| "name": "", | |
| "builderConfig": { | |
| "buckets": [], | |
| "tags": [ | |
| { | |
| "key": "_measurement", | |
| "values": [], | |
| "aggregateFunctionType": "filter" | |
| } | |
| ], | |
| "functions": [ | |
| { | |
| "name": "mean" | |
| } | |
| ], | |
| "aggregateWindow": { | |
| "period": "auto", | |
| "fillValues": false | |
| } | |
| } | |
| } | |
| ], | |
| "prefix": "", | |
| "tickPrefix": "", | |
| "suffix": "%", | |
| "tickSuffix": "%", | |
| "colors": [ | |
| { | |
| "id": "0", | |
| "type": "min", | |
| "hex": "#00C9FF", | |
| "name": "laser", | |
| "value": 0 | |
| }, | |
| { | |
| "id": "1", | |
| "type": "max", | |
| "hex": "#9394FF", | |
| "name": "comet", | |
| "value": 100 | |
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| "decimalPlaces": { | |
| "isEnforced": true, | |
| "digits": 2 | |
| }, | |
| "note": "", | |
| "showNoteWhenEmpty": false | |
| } | |
| } | |
| }, | |
| { | |
| "type": "view", | |
| "id": "08fc4b9c79fe1000", | |
| "attributes": { | |
| "name": "Temperature", | |
| "properties": { | |
| "shape": "chronograf-v2", | |
| "type": "gauge", | |
| "queries": [ | |
| { | |
| "text": "from(bucket: \"dht\")\n |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n |> filter(fn: (r) => r[\"_measurement\"] == \"temperature\")\n |> filter(fn: (r) => r[\"_field\"] == \"temperature\")\n |> filter(fn: (r) => r[\"host\"] == \"pi\")\n |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n |> yield(name: \"mean\")", | |
| "editMode": "advanced", | |
| "name": "", | |
| "builderConfig": { | |
| "buckets": [], | |
| "tags": [ | |
| { | |
| "key": "_measurement", | |
| "values": [], | |
| "aggregateFunctionType": "filter" | |
| } | |
| ], | |
| "functions": [ | |
| { | |
| "name": "mean" | |
| } | |
| ], | |
| "aggregateWindow": { | |
| "period": "auto", | |
| "fillValues": false | |
| } | |
| } | |
| } | |
| ], | |
| "prefix": "", | |
| "tickPrefix": "", | |
| "suffix": "°C", | |
| "tickSuffix": "°C", | |
| "colors": [ | |
| { | |
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| "type": "min", | |
| "hex": "#FFD255", | |
| "name": "thunder", | |
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| { | |
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| "type": "max", | |
| "hex": "#F95F53", | |
| "name": "curacao", | |
| "value": 100 | |
| } | |
| ], | |
| "decimalPlaces": { | |
| "isEnforced": true, | |
| "digits": 2 | |
| }, | |
| "note": "", | |
| "showNoteWhenEmpty": false | |
| } | |
| } | |
| }, | |
| { | |
| "type": "view", | |
| "id": "08fc4dc3b5fe1000", | |
| "attributes": { | |
| "name": "Temperature Graph", | |
| "properties": { | |
| "shape": "chronograf-v2", | |
| "queries": [ | |
| { | |
| "text": "from(bucket: \"dht\")\n |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n |> filter(fn: (r) => r[\"_measurement\"] == \"temperature\")\n |> filter(fn: (r) => r[\"_field\"] == \"temperature\")\n |> filter(fn: (r) => r[\"host\"] == \"pi\")\n |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n |> yield(name: \"mean\")", | |
| "editMode": "advanced", | |
| "name": "", | |
| "builderConfig": { | |
| "buckets": [], | |
| "tags": [ | |
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| ], | |
| "functions": [ | |
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| "aggregateWindow": { | |
| "period": "auto", | |
| "fillValues": false | |
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| "axes": { | |
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| "bounds": [ | |
| "", | |
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| "label": "", | |
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| "scale": "linear" | |
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| "", | |
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| ], | |
| "label": "Temperature", | |
| "prefix": "", | |
| "suffix": "°C", | |
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| "scale": "linear" | |
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| }, | |
| "type": "xy", | |
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| "colorizeRows": true, | |
| "opacity": 1, | |
| "orientationThreshold": 100000000, | |
| "widthRatio": 1 | |
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| "geom": "line", | |
| "colors": [ | |
| { | |
| "id": "ec36837f-84bd-43b6-be10-970343f0bbca", | |
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| "note": "", | |
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| "xColumn": "_time", | |
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| "hoverDimension": "auto", | |
| "legendColorizeRows": true, | |
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| "legendOpacity": 1, | |
| "legendOrientationThreshold": 100000000 | |
| } | |
| } | |
| }, | |
| { | |
| "type": "view", | |
| "id": "08fc4e064fbe1000", | |
| "attributes": { | |
| "name": "Humidity Graph", | |
| "properties": { | |
| "shape": "chronograf-v2", | |
| "queries": [ | |
| { | |
| "text": "from(bucket: \"dht\")\n |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n |> filter(fn: (r) => r[\"_measurement\"] == \"humidity\")\n |> filter(fn: (r) => r[\"_field\"] == \"humidity\")\n |> filter(fn: (r) => r[\"host\"] == \"pi\")\n |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n |> yield(name: \"mean\")", | |
| "editMode": "advanced", | |
| "name": "", | |
| "builderConfig": { | |
| "buckets": [], | |
| "tags": [ | |
| { | |
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| "values": [], | |
| "aggregateFunctionType": "filter" | |
| } | |
| ], | |
| "functions": [ | |
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| "label": "", | |
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| "scale": "linear" | |
| }, | |
| "y": { | |
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| "", | |
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| ], | |
| "label": "Humidity", | |
| "prefix": "", | |
| "suffix": "%", | |
| "base": "10", | |
| "scale": "linear" | |
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| }, | |
| "type": "xy", | |
| "staticLegend": { | |
| "colorizeRows": true, | |
| "opacity": 1, | |
| "orientationThreshold": 100000000, | |
| "widthRatio": 1 | |
| }, | |
| "geom": "line", | |
| "colors": [ | |
| { | |
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| "name": "Ectoplasm", | |
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| "type": "scale", | |
| "hex": "#ACFF76", | |
| "name": "Ectoplasm", | |
| "value": 0 | |
| } | |
| ], | |
| "note": "", | |
| "showNoteWhenEmpty": false, | |
| "xColumn": "_time", | |
| "generateXAxisTicks": [], | |
| "xTotalTicks": 0, | |
| "xTickStart": 0, | |
| "xTickStep": 0, | |
| "yColumn": "_value", | |
| "generateYAxisTicks": [], | |
| "yTotalTicks": 0, | |
| "yTickStart": 0, | |
| "yTickStep": 0, | |
| "shadeBelow": false, | |
| "position": "overlaid", | |
| "timeFormat": "", | |
| "hoverDimension": "auto", | |
| "legendColorizeRows": true, | |
| "legendHide": false, | |
| "legendOpacity": 1, | |
| "legendOrientationThreshold": 100000000 | |
| } | |
| } | |
| } | |
| ] | |
| }, | |
| "labels": [] | |
| } |
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.
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