In my previous post, I have explained how to mount a Grove Base Hat onto your Raspberry Pi and install the Seeed Studio provided grove.py software. In this post, I’m going to show you how to use a Grove Temperature and Humidity Sensor Pro with your Raspberry Pi.
Connecting the Grove Temperature and Humidity Sensor Pro with the Grove Base Hat for Raspberry Pi
Connecting the sensor with the base hat is straight forward.
First, put the cable into the sensor. There is only one way the cable fits, you will see two guiding tracks on one side of the cable that you have to fit into the socket accordingly.
On the Grove Base Hat, you have to attach the cable into the PWM socket, which is the top left one in the picture below. Just like the sensor, the cable only fits one way into the socket, watch out for the guiding tracks.
Reading the temperature and humidity from the sensor
Once the sensor is connected and the Raspberry Pi is powered up, you can reach your sensor on pin 12 (marked asPWM on the Grove Base Hat). However, before you can read the sensor, you will have to install one additional Python package called seeed-python-dht. You can install it with the following command: pip3 install seeed-python-dht
pi@gvenzl-raspberrypi-1:~ $ pip3 install seeed-python-dht Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple Collecting seeed-python-dht Downloading https://www.piwheels.org/simple/seeed-python-dht/seeed_python_dht-0.0.2-py3-none-any.whl Installing collected packages: seeed-python-dht Successfully installed seeed-python-dht-0.0.2
Once the package is installed, import it into your Python script, instantiate a new DHT object for sensor type DHT22 and pin 12, and read the sensor reading via the .read() method:
| #!/usr/bin/python3 | |
| # Press [Ctrl]+[C] to terminate the program | |
| import seeed_dht | |
| sensor = seeed_dht.DHT(seeed_dht.DHT.DHT_TYPE["DHT22"], 12) # DHT type 22, pin 12 | |
| try: | |
| while True: | |
| humi, temp = sensor.read() | |
| print('DHT{0}, humidity {1:.1f}%, temperature {2:.1f}C'.format(sensor.dht_type, humi, temp)) | |
| except KeyboardInterrupt: | |
| print("Exiting program.") |
The result will look like this:
pi@gvenzl-raspberrypi-1:~ $ ./Grove_Temperature_Humidity_Sensor_Pro.py DHT22, humidity 42.2%, temperature 23.0C DHT22, humidity 42.2%, temperature 23.0C DHT22, humidity 42.1%, temperature 23.0C DHT22, humidity 42.2%, temperature 23.0C DHT22, humidity 42.1%, temperature 23.0C DHT22, humidity 42.2%, temperature 23.0C ^CExiting program.
Notice: Unfortunately the Temperature and Humidity Sensor Pro doesn’t seem to be very reliable over a longer period of time. After a while, the sensor, or the provided Python library, it is still to be determined, stops reporting new readings and continues to report the last successful one. The only way that I have currently found to remedy the issue is by unplugging and plugging the sensor into the base hat again. I’m in contact with Seeed Studio Support on the matter and will update this post once we get to the root cause.
If you want to get your own Grove Temperature and Humidity Sensor Pro you can buy it here from Seeed Studio.
One thought on “How to use a Grove Temperature and Humidity Sensor Pro with a Raspberry Pi”