{"id":13210,"date":"2015-08-26T09:08:59","date_gmt":"2015-08-26T08:08:59","guid":{"rendered":"http:\/\/www.recantha.co.uk\/blog\/?p=13210"},"modified":"2015-08-30T18:31:09","modified_gmt":"2015-08-30T17:31:09","slug":"sensehat-launched-by-the-foundation-a-first-look","status":"publish","type":"post","link":"https:\/\/www.recantha.co.uk\/blog\/?p=13210","title":{"rendered":"SenseHAT launched by the @Raspberry_Pi Foundation – an extensive first look"},"content":{"rendered":"

\"#Camu\"<\/a><\/p>\n

This morning, the Raspberry Pi Foundation announced<\/a> the immediate availability of the SenseHAT<\/strong>. The SenseHAT is the guts of the Astro Pi<\/a>\u00a0and has\u00a0an inherent space-aged\u00a0coolness built in. The board you hold in your hands is the same hardware that is going into space (enormous metal flight case not included<\/a>). I was fortunate enough to be given one to look at and review.<\/p>\n

If you\u00a0prefer to get your information from a video, jump straight to the video demo<\/a><\/strong>.<\/p>\n

If you don’t want to read everything and want to know where to buy one from, jump to the Pricing section<\/a>.<\/p>\n

Background<\/strong><\/p>\n

\"\"As I said above, the SenseHAT is the heart of the Astro Pi. British astronaut Tim Peake<\/a> will be launching on 15th December on a mission known as “Expedition 46<\/a>” (or Soyuz TMA-19M). Part of the payload of the spacecraft will be two Raspberry Pi model B+s with SenseHATs attached, wrapped in a\u00a0metal flight case<\/a>. Also contained within each\u00a0case is a Pi camera: one is a regular camera, the other is a PiNoIR.\u00a0The Soyuz spacecraft\u00a0will lift off and travel to the International Space Station and return on 5th\u00a0May\u00a0next year. During the mission, Peake (and possibly other astronauts) will trigger experiments on the Pis that school children have written<\/a>.<\/p>\n

<\/div>\n

Hardware<\/strong><\/p>\n

The SenseHAT\u00a0has the following features:<\/p>\n

    \n
  • A temperature and humidity sensor.<\/li>\n
  • A pressure sensor.<\/li>\n
  • A sensor combining a 9-degrees-of-freedom accelerometer, gyroscope and magnetometer.<\/li>\n
  • An 8×8 matrix of bright LEDs controlled by an onboard Atmel Tiny 88 chip.<\/li>\n
  • A 4-way digital joystick with a push button in the middle.<\/li>\n<\/ul>\n

    For full technical specifications, take a look at the Foundation’s blog post<\/a>. For\u00a0the technical schematic, take a look here<\/a>.<\/p>\n

    Software<\/strong><\/p>\n

    The software was easy to install. I won’t go into the method I used to install as the ‘official’ way is slightly different. According to the GitHub repository<\/a> (which hadn’t been updated when I\u00a0took the other route) says installing is as simple as this:<\/p>\n

    sudo apt-get update\r\nsudo apt-get install sense-hat\r\nsudo pip-3.2 install pillow\r\nsudo reboot<\/pre>\n
    You only need “pillow” if you’re going to program in Python 3.<\/em><\/p>\n
    * If you have any problems getting it working after these installs, try enabling I2C through raspi-config<\/em>.<\/p>\n
    The main bulk of the software\u00a0is a Python library that I believe works in both Python 2 and Python 3. You use the library by first of all\u00a0importing the package:<\/p>\n
    from sense_hat import SenseHat<\/pre>\n
    and then instantiate the module as an object:<\/p>\n
    sense = SenseHat()<\/pre>\n
    You can then use the in-built functions to access data from all the sensors and display information on the 8×8 matrix.<\/p>\n
    All the software is on GitHub in case you need to look at it<\/a>\u00a0and there is an API guide over at PythonHosted.org<\/a>\u00a0– pay particular attention to the API documentation (most notably\u00a0set_imu_config() if you want to get the compass working correctly!)<\/p>\n
    Examples<\/strong><\/p>\n
    The software comes with a few examples to get you going. They are:<\/p>\n
      \n
    • colour_cycle.py – lights up the 8×8 matrix and cycles through a lot of the colours available to you when programming it.<\/li>\n
    • compass.py – by holding the Pi in\u00a0the right orientation, the 8×8 matrix shows a dot pointing North.<\/li>\n
    • pygame_joystick.py – a PyGame script that takes input from the joystick on the SenseHAT and lights up in the appropriate position. The joystick mimics the up-down-left-right arrows and carriage return, making it easy to pick up on the ‘key presses’ in Pygame.<\/li>\n
    • rainbow.py – a simple test of the 8×8 matrix – it displays an animated rainbow (see picture below\u00a0– thanks to Alex Eames<\/a> for the photo as my one didn’t show it off very well!).<\/li>\n
    • rotation.py – displays a ? symbol and rotates it through 4 different orientations. Rotation is\u00a0really<\/em> easy using the library.<\/li>\n
    • space_invader.py –\u00a0loads an image file of a space invader icon and displays it on the 8×8 matrix.<\/li>\n
    • text_scroll.py – scrolls a message across the 8×8 matrix. Again, the library makes scrolling text\u00a0very simple.<\/li>\n<\/ul>\n
      \"Astro2comp_sm\"<\/a><\/p>\n
      Photo credit: Alex Eames<\/a><\/h5>\n
      Taking things further<\/strong><\/p>\n
      I wanted to try out a few things on the board but didn’t have the time to create something myself. So, I took to Google and GitHub and found these terrific examples.<\/p>\n
        \n
      • A snake game<\/a>\u00a0by Martin O’Hanlon<\/li>\n
      • Using the SenseHAT to rotate a model of a spacecraft<\/a>\u00a0by\u00a0Serge Schneider<\/a>.<\/li>\n
      • Some other examples<\/a> by Ben Nuttall<\/li>\n<\/ul>\n
        If you try these examples, you\u00a0may<\/em> have to change library references from\u00a0“AstroPi” to “SenseHat”.<\/p>\n
        <\/a>
        \nVideo demo<\/strong><\/p>\n
        You can see a\u00a0video of some of these examples as well as a general overview of the board below. I apologise for the abrupt cut-off – I ran out of space on my mobile\u00a0phone!<\/em><\/p>\n