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Friday 10 January 2020

Getting Started with The Sense HAT — Raspberry Pi

Read this story on my blog https://iotbyhvm.ooo/sense-hat/
The Raspberry Pi Sense HAT is a useful and somewhat confusingly named interface board for the RPi. It includes sensors, we can
measure Temperature, Relative humidity and Pressure. Accelerometer, Gyroscope and magnetometer are available. It also has a full-color 8*8
LED matrix display. Sense HAT requires a RPi with 40 Pin GPIO header and some softwares to be installed before you can use it.

What you will need

Hardware
  • Raspberry Pi
  • Sense HAT
Software
You will need the latest version of Raspbian which already includes the following software packages:
  • Python 3
  • Sense HAT for Python 3
If for any reason you need to install a package manually, follow these instructions:

Install the Sense HAT Python library

Install the Sense HAT Python library by using the command
sudo apt-get install sense-hat
This installer will actually enable I2C automatically, So you do not need to follow the usual I2C setup. Sense HAT’s Display uses a graphics library called Python Image Library (PIL), which must be installed by using the command:
sudo pip-3.2 install pillow
Installation will take a while, after which you should reboot if I2C was not already enabled.
So Now we can check that everything is working or not, by opening Python console using:
sudo python
Now enter these commands
>>> from sense_hat import SenseHat
>>> hat = SenseHat()
>>> hat.show_message('RPi Tutorials by IoTbyHVM')
Now LED matrix should then display the text of the message above, scrolling it across the screen.


Measuring temperature, Humidity, and Pressure with a Sense HAT

Now we are going to measure temp, humd and pressure with SenseHat. Open any text editor or IDLE and Paste given below code.
and save with sense_thp.py.
# Program for measuring temperature and humidity and pressure with Sense Hat
# Visit https://iotbyhvm.ooo IoTbyHVM.ooo Explore TechBytesfrom sense_hat import SenseHat
import timehat = SenseHat()while true:
    t = hat.get_temperature()
    h = hat.get_humidity()
    p = hat.get_preesure()
    print ('Temp C:{:.2f} Humd:{:.0f} Pres:{:.0f}' .format(t, h, p ) )
    time.sleep(1)
Output will like this:
sudo pyhton sense_thp.py
Temp: C:27.12 Humd:45 Pres:1232
Temp: C:27.45 Humd:44 Pres:1231
Here temp is in degree C, Humdity is in the percentage and Atmospheric Pressure is in milibars.

Sensing a Magnet with Sense HAT

Yes, you can sense magnet with Sense hat because SenseHAT has magnetometer. Follow code given below:
# Sense magnet with SenseHAT
from sense_hat import SenseHat
import timehat = SenseHat()
fill = (255,0,0)while true:
    reading = int(hat.get_compass_raw()['z'])
    if reading > 200:
        hat.clear(fill)
        time.sleep(0.2)
    else:
        hat.clear()
now run this program, when the magnet gets close to SenseHAT, the LEDs will all turn red for 1/5 of a second.

Finding magnetic North with Sense HAT | How To make Compass

from sense_hat import SenseHat
import timehat = SenseHat()while true:
    bearing = sense.get_compass()
    print ('bearing: {:.0f} to north' .format(bearing))
Output:
sudo python sense_compass.py
Bearing : 138 to north
Bearing : 138 to north

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